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THE INTERNATIONAL SCIENTIFIC SERIES 
 
 
 THE 
 
 AURORA BOREALIS 
 
 BY 
 
 'ALFEED ANGOT 
 
 HONORARY METEOROLOGIST TO THE CENTRAL 
 MBTEOROLOQICAL OFFICE OF FRANCE 
 
 WITH EIGHTEEN ILLUSTRATIONS 
 
 NEW YORK 
 D. APPI.ETON AND COMPANY 
 
 1897 
 
Authorized Edition. 
 
PEEFAOE. 
 
 The first work, devoted entirely to the study of Polar 
 Auroras, was written in France ; it is entitled ' Traite 
 Physique et Historique de 1' Aurora Boreale,' and was 
 published in 1733 by De Mairan, in the 'Memoires' 
 of the ' Academie des Sciences.' We must allow a cen- 
 tury to elapse before we find anything to be compared 
 with it in importance and volume, when the work 
 ' Aurores Boreales ' appeared in the collection of the 
 voyages of the Northern Scientific Commission on the 
 corvette * Eecherche.' This volume, accompanied by 
 magnificent plates — of which we shall reproduce the 
 most interesting — contains records of observations of 
 the aurora boreaHs taken in Lapland during the 
 winter of 1838-39 by Bravais, Lottin, Lillihoeoek, and 
 Siljestroem. Bravais added general remarks on this 
 phenomenon, and discussed the principal observations 
 collected at that date, and the various hypotheses put 
 forward to account for them. 
 
VI THE POLAR AURORA. 
 
 Since then no general work on the subject has 
 appeared in this country. The student was obliged 
 to consult original papers published in all languages, 
 or foreign treatises, among which we will men- 
 tion only one as the most complete, that of Her- 
 mann Fritz of Zurich, ' Das Polarlicht ' (Leipzig, 
 1881), 
 
 I have tried to meet this want by writing in the 
 journal ' LaLumiere Electrique ' (vol. vii., last half of 
 1882) a series of ten articles on the Polar Aurora, 
 accompanied by numerous plates, which reproduce 
 from the original documents the principal appearances 
 of the polar aurora. These articles, revised according 
 to the most recent discoveries, have served as the 
 basis of the present work. 
 
 It would have been easy to increase considerably 
 the size of this volume by citing a greater number 
 of the results of observations. I thought, however, 
 that it was better to choose for each class of phenomena 
 two or three of the most conclusive examples, borrowed 
 from those observers who are most worthy of con- 
 fidence. I have not tried to publish all the obser- 
 vations collected at all times and in all countries on 
 Polar Auroras. I have rather sought to give a sketch 
 of the actual state of our knowledge of this question, 
 noting the results which may be considered as defi- 
 
PEEFACE. Vii 
 
 nitely acquired, and also the points on which further 
 research seems unnecessary. 
 
 I have indicated in the course of the work the 
 most important books and papers on each branch of 
 the subject ; but here, also, some limit was necessary. 
 For these works must now be reckoned by hundreds, 
 some containing merely observations of the aurora, 
 others theories about it. A complete bibliography 
 of the subject would alone fill a large volume. 
 
 The figures in the text are reproduced directly, and 
 as exactly as possible, from the original documents, 
 and their source is always indicated. They are taken 
 partly from the fine atlas of Bravais, which contains the 
 most beautiful engravings of the aurora borealis which 
 have yet been published. I have been able to add draw- 
 ings which are less known, and some never before 
 published. In particular, my thanks are due to M. de 
 la Monneraye, a lieutenant in the navy, who kindly 
 placed at my disposition a remarkable series of draw- 
 ings which he executed himself in the course of a 
 sojourn in the seas near Newfoundland. 
 
 In the Appendix will be found a list of all the 
 appearances of the aurora borealis. observed from 1700 
 to 1890 in Europe below the 55th parallel of latitude. 
 Above this Hmit auroras are so frequent that at cer- 
 tain epochs they may be seen almost every day. In 
 
VIU THE POLAE AUEORA. 
 
 drawing up this catalogue I have chiefly followed that 
 of Fritz, which is a summary of all previous cata- 
 logues. I have only had to add the observations of 
 the last twenty years. Such catalogues are indis- 
 pensable for almost all the studies which relate to 
 Polar Auroras ; and since Mairan's, in the middle of the 
 last century, none had been published in France. The 
 service which this catalogue may render will, I hope, 
 excuse its length and aridity. 
 
CONTEISTTS. 
 
 CHAl'TBR PAOB 
 
 I. HiBTOBT 1 
 
 II. FOKMS or THE POLAB AnE0K4 12 
 
 1. Faint lights without definite form .... 13 
 
 2. Lights in the form of clouds. Auroral bands and 
 
 patches 14 
 
 3. Homogeneous arcs 20 
 
 4. Non-homogeneous, or rayed arcs . . . . 22 
 
 5. Auroral rays and crowns 28 
 
 6. Draped auroras 82 
 
 III. Phtsioaii Chaeaoteks of the Polab Auboba . . 34 
 
 1. Colour of the aurora 34 
 
 l^ 2. Intensity of the light of the aurora ... 37 
 
 '■■ 3. Nature of the light of the aurora . . . . 40 
 
 4. Sound of the aurora 46 
 
 " 0. Odour of the aurora 51 
 
 IV. Extent, Position, and Fbequency or the Aueoea . 52 
 
 1. Extent of the aurora 52 
 
 2. Height of the aurora 56 
 
 3. Frequency of the aurora 69 
 
 4. Direction in which the aurora is seen ... 74 
 
 V. PjiEIODIOITY OF THE AuEOBA 79 
 
 1. Diurnal period 79 
 
X THE POLAE AUEOEA, 
 
 CHAPTER PAGE 
 
 2. Annual period 84 
 
 3. Secular periods. Eelations of the aurora with the 
 
 solar spots 91 
 
 VI. Eelations op the Aoeoea with Meteoeolooical 
 
 Phenomena 104 
 
 1. With the weather 104 
 
 2. With the clouds 108 
 
 3. With atmospheric electricity 113 
 
 VII. Eelations of the Aueoea with Teeeestbial Mas- 
 
 NETISM AND TeLLUEIO CuBBENTS . . . . 120 
 
 1. With the general distribution of terrestrial mag- 
 
 netism 120 
 
 2. With magnetic disturbance 128 
 
 3. With telluric currents 138 
 
 VIII. Theoeies of the Aueoea 147 
 
 1. Cosmic theories 147 
 
 2. Optical theories 151 
 
 3. Magnetic theories 154 
 
 4. Electrical theories 158 
 
 Appendix : Catalogue of the auroras observed in Europe below the 
 65th parallel of latitude from 1700 to 1890. 
 
LIST OF ILLUSTEATIONS. 
 
 PLATES 
 
 Fid. 
 
 1. BossEKOP (Lapland) Aubora with Arc and Drapery Frontispiece 
 
 2. Wlntebinq OF THE ' Vega.' Elliptical Arcs . To face p. 21 
 
 3. WmiERiNO OF THE ' Vega.' Ellipiical Arcs . „ 21 
 
 4. WiNTEBma OF the ' Vega.' Multiple Arcs . „ 22 
 
 5. WlNTEKlNO OF THE ' VeGA.' MdLTIPLE ArCS 
 
 with Different Centres .... „ 22 
 
 6. BossEKOP. Successive Appearances of the same 
 
 Aurora „ 23 
 
 7. Paris. Bated Arc „ 25 
 
 8. Bay of Islands, Newfoundland. Bayed Aurora „ 29 
 
 9. Bay of Islands. Eayed Aurora .... „ 29 
 
 10. Bay of Islands. Eastern Half op a Corona 
 
 borealis „ 31 
 
 11. Bay of Islands. Western Half of a Corona 
 
 borealis „ 30 
 
 12. BosSEKOP. Draped Aurora . . . . „ 33 
 
 13. BossEKOP. Draped Aurora ... • » 34 
 
XU THE POLAE AUEOEA. 
 
 Fib. 
 
 14. BossEKOP. Dkaped AnEOKA WITH Hook . . To face p. 35 
 
 15. Melboubke. Aurora with Abcs aud Corona 
 
 austealis „ 36 
 
 18. Paeis. Draped Adboka ..... .. 40 
 
 illusteations in text 
 
 Pase 
 
 16. Chart of the Phequenot of the Auboba Boebaus . . 133 
 
 17. CoMPAEISON OF THE FeEQUENOT OF THE AuEOEA WITH THE 
 
 Spots on the Sun iJ7 
 
THE POLAE AUEOEA. 
 
 CHAPTEE I. 
 
 HISTOKY. 
 
 Polar auroras, which are subdivided into aurora 
 borealis and aurora australis, according to the hemi- 
 sphere in which they occur, are assuredly the finest 
 of the optical phenomena of nature, but are, even at 
 the present day, one of the least understood. While 
 by their sudden appearance, their superb colouring, 
 their rapid movement, their infinitely varied form, 
 the northern lights have from all time excited the 
 attention of the multitude, their mysterious nature 
 and the relations which seem to connect them with 
 terrestrial magnetism, and even with certain cosmic 
 phenomena, such as the spots in the sun, make 
 them the subject of the study of meteorologists and 
 physicists. 
 
 The aurora borealis was already known to the 
 Greeks and Eomans, although it is a rare pheno- 
 menon in districts so far south as the shores of the 
 3 
 
2 THE POLAE AUROEA. 
 
 Mediterranean. Aristotle touches on tbem briefly 
 in his ' Meteorology.' ' He says that they sometimes 
 present the appearance of the smoke of the straw 
 which is burnt in the country, and his observation is 
 exact. - Other forms of the aurora borealis are 
 designated by him under the name of brands (BaXol) 
 and goats (alyss ) : the author enters into no explana- 
 tion, but this last name may plausibly be referred 
 to certain luminous rays, of which we shall speak 
 later, which show rapid alternative movements in the 
 direction of their length, and thus appear to leap. 
 Further on, among the phenomena which may be ob- 
 served on calm nights, Aristotle enumerates gulfs 
 and abysses {■^da-fiaTa, ^oOvvoi) and sanguine colours. 
 The first two expressions doubtless refer to what is 
 now known as the obscure segment, the dark part of 
 the heaven which is seen in the form of an arc, below 
 the aurora. This identification appears the more 
 probable that Aristotle adds : ' The gulfs seem to have 
 a certain depth because of the contrast which the light 
 makes with the black and blue colour of the sky. 
 Often even, when they contract, brands or torches 
 issue from them {haXol in Greek) ; the gulf then 
 seems to converge.' These few lines appear to be 
 absolutely incomprehensible in certain French trans- 
 lations ; as rendered above they correspond with 
 sufficient accuracy to certain aspects of the aurora 
 borealis. 
 
 ' Lib. i. 4 and 5. 
 
HISTOEY. 3 
 
 Cicero merely mentions twice the aurora, which 
 he indicates by the term torches.^ 
 
 Pliny, the naturalist, is much more explicit,^ and 
 he cites the precise epochs at which the phenomenon 
 was observed. 
 
 ' Beams (trabes) are seen to shine in the heaven, 
 which are called Bo/col in Greek, as it happened at 
 the time when the Lacedaemonians, vanquished at sea, 
 lost the dominion over Greece. In the sky appears a 
 gulf which is called chasma (the Greek word trans- 
 lated directly into Latin). And, besides, there is seen 
 in the heaven (and nothing is more terrible for 
 trembling mortals) blood-coloured flames which 
 afterwards fall upon the earth, as it happened in the 
 third year of the hundred and seventh Olympiad, 
 when King Philip ruled over Greece. Under the 
 consulate of C. Csecilius and Cn. Papirius, and on 
 many other occasions, a light was seen in heaven 
 which made the night almost as light as day. It is 
 said that at the time of the wars of the Cimbri, and 
 also often before and since, the clashing of arms and 
 the sound of trumpets were heard in the sky. But in 
 the third consulate of Marius the dwellers in Ameria 
 and Tuderta saw in the heavens two armies rushing 
 one against the other from the east and from the 
 west ; that of the west was defeated. The heaven 
 
 ' De Natura Deorum, ii. 5 : ' turn faoibug visis cselestibus ; ' 
 Catilm. III. viii. : ' -visas nooturno tempore ab oocidente faces 
 ardoremque cseli.' 
 
 2 Hist. Nat. ii. 26, 27, 33, and 57. 
 
4 THE POLAE AUEOEA. 
 
 itself caught fire : this is no extraordinary thing, and 
 it has often been seen when the clouds are exposed 
 to great heat.' ' 
 
 In this quotation from Pliny we find for the first 
 time the trace of that popular superstition which 
 obtained almost down to our own day, and which 
 attributed the great auroras to armies combating in 
 the sky. 
 
 Seneca ' gives a few more details, curiously exact, 
 showing that observers in classic times were often 
 more accurate than those of several centuries later. 
 Speaking of the different sorts of heavenly fires, 
 Seneca describes a certain number of appearances 
 which are clearly the aurora borealis ; but instead^ of 
 using Latin words to describe them he borrows the 
 Greek terms of Aristotle, which we gave above. Here 
 is the passage from Seneca : — 
 
 ' Sometimes flames are seen in the sky, either 
 stationary or full of movement. Several kinds are 
 known : the abysses, when beneath a luminous crown 
 the heavenly fire is wanting, forming as it were the 
 circular entrance to a cavern; the tuns (pithitce), 
 when a great rounded flame in the form of a barrel is 
 seen to move from place to place, or to burn immo- 
 vable the gulfs (cJiasmata), when the heaven seems 
 to open and to vomit flames which before were hidden 
 in its depths. These fires present the most varied 
 colours : some are a vivid red ; others resemble a faint 
 
 ' Naturales Qucestiones, i. 14, 15. 
 
HISTOEY. 5 
 
 and dying flame ; some are white ; others scintillate ; 
 others finally are of an even yellow, and emit neither 
 raya nor projections. Among these phenomena 
 should be ranged those appearances as of the heavens 
 on fire so often reported by historians ; sometimes 
 these fires are high enough to shine among the stars ; 
 at others, so low that they might be taken for the re- 
 flection of a distant burning homestead or city. This 
 is what happened under Tiberius, when the cohorts 
 hurried to the succour of the colony of Ostia, believ- 
 ing it to be on fire. During the greater part of the 
 night the heaven appeared to be illuminated by a 
 faint light resembling a thick smoke.' 
 
 The mistake mentioned by Seneca is so natural 
 that it has often occurred since. At Copenhagen, 
 in 1709, during a large and brilliant aurora, several 
 battalions turned out under arms and beating drums. 
 
 The Greek and Eoman authors often confounded 
 certain faint auroras with comets, and it is probable 
 that the catalogues of early appearances of comets 
 contain many errors of this description. The mis- 
 take is manifest when it is stated in the description 
 that the comet appeared in the north and only 
 lasted a few hours, or even less ; in this case it was 
 simply a ray of the aurora borealis. Such, for instance, 
 was the supposed comet of October 11, 1527, in France, 
 in Germany, and almost the whole of Europe : it was 
 of immense length ; its summit was like an arm, bent 
 at the elbow ; it was only visible towards the north. 
 
6 THE POLAR AUEOEA. 
 
 and lasted but an hour and a quarter. It was of an 
 orange-red colour, ' and joined to it were dark rays 
 in the form of tails, lances, bloody swords, figures 
 of men, and heads cut off, bristling with hair and 
 beards.' From all these details it is easy to recognise 
 in the phenomenon an aurora borealis. 
 
 Among early records of the aurora we will 
 cite yet another, mentioned by Gregory of Tours. 
 He says he saw the appearance himself, and his 
 description is interesting; both from its simplicity 
 and accuracy, and because the form now known as 
 the ' boreal crown ' is clearly indicated for the first 
 time : ' Two nights in succession we saw signs in the 
 heavens, that is to say rays of light which rose in 
 the north, as often happens. A great light took 
 possession of a part of the sky and seemed to over- 
 flow it. • . . There was in the middle of the heaven 
 a cloud of light, towards which all the rays converged, 
 in the form of a tent of which the sides, much wider 
 at the foot, ascended, narrowing to the summit, where 
 they united, often in the shape of a hood.' ' 
 
 Gregory of Tours in several other places mentions 
 the aurora borealis, and his descriptions are always 
 equally simple : he considers the aurora as a curious 
 manifestation, but attaches to it no idea of the 
 supernatural. Some centuries later astrology had so 
 troubled the minds of men that the aurora borealis 
 had become a source of terror : bloody lances, heads 
 
 ' Eistoria Francorum, viii. 17. 
 
HISTORY. 7 
 
 separated from the trunk, armies in conflict, were 
 clearly distinguished. At the sight of them people 
 fainted (according to Cornelius Gemma), others went 
 mad. Pilgrimages were organised to avert the wrath 
 of Heaven, manifested by these terrible signs. Thus, 
 according to the Journal of Henri III., in the month 
 of September 1583 eight or nine hundred persons of 
 all ages and both sexes, with their lords, came to 
 Paris in procession, dressed hke penitents or pilgrims, 
 from the villages of Deux-Gemeaux and Ussy -en-Brie, 
 near La Ferte-Gaucher, ' to say their prayers and 
 make their offerings in the great church at Paris ; 
 and they said that they were moved to this penitential 
 journey because of signs seen in heaven and fires in the 
 air, even towards the quarter of the Ardennes, whence 
 had come the first such penitents, to the number of 
 ten or twelve thousand, to Our Lady of Eheims and 
 to Liesse.' The chronicler adds that this pUgrim'age 
 was followed a few days afterwards by five others, and 
 for the same cause. 
 
 These superstitious terrors lasted at least till the 
 end of the seventeenth century. La Mothe le Vayer, 
 who was tutor to the Duke of Orleans, brother of 
 Louis XIV., and afterwards to Louis XIV. himself, 
 and who entered the Academy in 1639, alludes to 
 these popular beliefs in his 78th letter, entitled 'De la 
 Credulite : ' ' I will take my second example (of 
 credulity) from the writings of Baptiste le Grain, for 
 whom I have a great esteem : he says in his sixth 
 
8 THE POLAR ATIROEA. 
 
 book that he observed in Paris in 1615, about eight 
 o'clock in the evening of the 26th of October, men of 
 fire in heaven, who fought with lances, and who by 
 this terrifying spectacle foretold the fury of the wars 
 which followed. Yet I was with him in the same 
 town, and I protest, having studied attentively until 
 eleven at night the phenomenon of which he speaks, 
 that I saw nothing similar to his description, but 
 only an appearance which is sufficiently common, in 
 the form of pavilions in the sky flaming up and 
 fading out again, as is usual with such meteors. A 
 number of persons now living will testify to what I 
 say.' 
 
 It was towards this epoch that, as a result of the 
 observations of Gassendi, and later of those of Cassini, 
 of Eoemer, &c., the aurora ceased to be regarded, at 
 any rate by the educated classes, as a supernatural 
 phenomenon, presaging horrible calamities. Yet even 
 at the present day, in rural districts, simple folk might 
 be prone to attribute a supernatural origin or signifi- 
 cance to the aurora if its appearance should chance 
 to coincide with striking events or great disasters. 
 Perhaps some vestiges of this ancient superstition 
 might have been found at the time of the remark- 
 able aurora borealis which was observed through- 
 out France during the nights of October 24 and 25, 
 1870. 
 
 The Norsemen believed that the aurora represented 
 the Valkyries riding through the air on their sombre 
 
HISTORY. 9 
 
 horses. This belief, indicated by Tacitus in his de- 
 scription of Germany, is given more explicitly in 
 several passages of the Edda. But since this 
 phenomenon is of common occurrence in the north, 
 familiarity early deprived it of all its terrors. About 
 the year 1250, less than a century after the composi- 
 tion of the Edda, a Norwegian, who probably lived 
 near the town of Nansos (to the north of Trondhiem), 
 wrote a work, at once philosophical and political, 
 entitled 'The King's Mirror' (Konungs Skitggsja), 
 which is remarkable on more than one count : in 
 it the aurora is thus described : • — 
 
 •The. nature and constitution of the northern 
 lights are such that the darker the night the brighter 
 they shine : they are never seen by day, but only at 
 night, especially in profound obscurity, and rarely by 
 moonUght. They appear like a great flame seen from 
 a distance, as though that of a vast fire. From the 
 smoke of it pointed shafts of unequal and very vari- 
 able size seem to dart upwards into the air, so that 
 now the one and now the other is the higher, and 
 they seem to quiver like flames. When these rays 
 are at their highest and brightest they give so much 
 light that one can find one's way about quite easily 
 out of doors, and even hunt if this is desired. In 
 houses with windows it is Ught enough within for men 
 to see each other's faces. This Ught is so variable 
 
 ' Sophus Tromholt, Zur OescUchte des Nordlichts (Meteoro- 
 logische ZMschrift, vol. ii. 1885, p. 24). 
 
10 THE POLAE AXJEOEA. 
 
 that it sometimes becomes obscured, as though it were 
 covered by thick smoke or cloud ; and soon it seems 
 to be stifled by this smoke and near extinct. But as 
 soon as the cloud begins to dissipate and grow less 
 thick, the light increases and glows again, and some- 
 times great sparks seem to fly from it, as from a red- 
 hot iron taken from the forge. As the night advances 
 and dawn approaches, this light begins to pale, and it 
 fades altogether when day breaks. Certain people 
 maintain that this light is a reflection of the fire 
 which surrounds the seas of the north and of the 
 south ; others say that it is the reflection of the sun 
 when it is below the horizon ; for my part. I think 
 that it is produced by the ice which radiates at night 
 the light which it has absorbed by day.' 
 
 Note, by the way, this first attempt at an explana- 
 tion of the polar auroras. Doubtless it is not very 
 convincing and would not be considered satisfactory 
 at the present day ; but we must not smile at it, since 
 it is nearly the same as that which many centuries 
 later was suggested both by Descartes and Sir John 
 Franklin. 
 
 We may add, in concluding this historical sketch, 
 that Gassendi, in 1621, first used the term aurora 
 borealis. In the seventeenth century and even in a 
 part of the eighteenth, as this appearance was not 
 known to exist in the southern hemisphere, the light - 
 was called borealis when it appeared in the northern 
 quarter of the sky, and australis when it appeared to 
 
HISTORY. 11 
 
 the south, but always to an observer in the northern 
 hemisphere. 
 
 Although polar auroras were seen in Chili as early 
 as 1640, the first certain observations taken in the 
 southern hemisphere and known in Europe were those 
 of Antonio de Ulloa. During the voyage round Cape 
 Horn in 1745 he more than once had occasion to 
 observe a polar aurora, and he maintains that they 
 must be as frequent in the southern hemisphere as in 
 our own. Since then the name of aurora borealis has 
 been restricted to those which are seen in the northern 
 hemisphere, round the north pole, and that of aurora 
 australis to those which are seen round the south 
 pole. The name polar aurora, therefore, is to be 
 preferred as being more general. 
 
 In England and the United States the name 
 proposed by Gassendi has been adopted in scientific 
 phraseology to designate this phenomenon. The 
 sailors of the north of England call them northern 
 lights, or streamers. In Germany and Scandinavian 
 countries the ancient name of northern light which 
 we find in 'The King's Mirror' has been retained, 
 Nordlicht in German, Nordljus in Swedish, Nordlys in 
 Danish. 
 
12 THE POLAR AUEOEA, 
 
 CHAPTEE II. 
 
 FOEMS OF THE POLAE ADEOEA. 
 
 The polar aurora offers the most varied and complex 
 forms, as the reader can judge from the illustrations 
 in this work, which reproduce as faithfully as possible 
 the original drawings made by competent observers 
 in presence of the phenomenon. The source of each 
 engraving is always indicated, thus facilitating the 
 reference to the original descriptions. 
 
 We shall divide the polar auroras into two great 
 classes : those which are apparently motionless, or at 
 least of which the various parts retain for a certain 
 time their relative position and intensity ; and those 
 which, on the other hand, present rapid and incessant 
 variations in shape and brilliancy. In the first class 
 we distinguish three principal forms : 
 
 1. Paint lights without very defined form. 
 
 2. More distinct lights, grouped in patches which 
 often present the appearance of clouds. 
 
 3. Clearly defined arcs, formed of a homogeneous 
 luminous mass touching the horizon at either ex- 
 tremity. 
 
 In the second class, that of auroras presenting 
 
FOEMS OF THE POLAE AUEOEA. 13 
 
 rapid movements, three principal subdivisions are also 
 observed. 
 
 4. Non-homogeneous arcs, of which the brilliancy 
 is not uniform, nor the border regular ; from these 
 arcs rays shoot upward intermittently. 
 
 5. Eays isolated from each other, at a greater or 
 less distance: they seem to converge upon a fixed 
 point in the sky, and sometimes form round this point 
 a sort of glory or crown. 
 
 6. Non-homogeneous bands, formed of rays pressed 
 close together which have not aU the same degree of 
 brilliancy. These bands of light have a height pro- 
 portioned to their width : sometimes they seem to 
 fold over on themselves, and then they become the 
 draped auroras, which are the most beautiful mani- 
 festations of the polar aurora. 
 
 These different forms, which we separate for 
 purposes of description, and which, moreover, are most 
 often seen singly, may yet exist simultaneously or 
 successively in the same aurora, as we shall see in the 
 examples given in the course of this study. 
 
 1. Faint lights without very definite form. — There 
 is not very much to say about these faint and ill- 
 defined lights, which constitute the first type of polar 
 auroras. They are of the most varied dimensions, 
 sometimes very small, sometimes occupying almost 
 the whole heaven: their brilliancy is at times not 
 greater than that of the Milky Way ; they then form, 
 as it were, a white veil over the sky. At other times 
 
14 THE POLAE AURORA. 
 
 they only feebly light up the horizon, and it ia 
 probable that under this form .they often pass un- 
 observed, either because they are masked by a stronger 
 light, such as that of the moon, or by that reflected 
 in the sky by the illumination of great, towns, or 
 because they are taken for the last rays of the sunset 
 or the first of the dawn. At times, again, when their 
 light is somewhat stronger, they appear on the 
 horizon as the reflection of a distant fire, illuminating 
 the edges of the dark clouds which interpose between 
 them and the spectator. Finally — but this is rare — the 
 focus of these hghts may be, not on the horizon, but 
 at some distance above it, though the elevation is 
 never many degrees. 
 
 Faint auroras of this class are often called Licht- 
 frocess by German authors : they appear to be of 
 frequent occurrence in Europe, but they escape the 
 attention of all but careful observers whose attention 
 is specially directed to this phenomenon. 
 
 It is perhaps with this species of polar aurora 
 that we should connect the sort of phosphorescence 
 which on certain nights illumines the whole atmo- 
 sphere. Such a light was observed at Gottingen 
 during the night of November 13 and 14, 1866, when, 
 without apparent cause, the sky remained as light as 
 it is usually in the shortest summer nights. 
 
 2. Lights in the form of clouds. Auroral bands 
 and patches. — The greater number of auroras which 
 have been observed in France belong to this class. 
 
FOEMS OF THE POLAR AUEOEA. 15 
 
 They are vague lights withont very defined outline, of 
 which the colour is generally a yellowish or greenish 
 white, more rarely a beautiful rose colour. They 
 afifect, for instance, the form of clouds of smoke, like 
 the aurora which was observed and drawn in Febru- 
 ary 1874, by the expedition under Payer and Wey- 
 precht on board the 'Tegetthof at Franz Josef 
 Land. Still more often they resemble those light 
 clouds, like feathers or tufts of carded cotton, known 
 to meteorologists as cirrus. 
 
 This species of aurora is often seen alone, or it 
 may mark the beginning and the end of more com- 
 plete auroras. 
 
 The resemblance between some of these auroras 
 and cirrus clouds may be so close that it becomes 
 sometimes impossible to distinguish whether we are 
 really gazing on a manifestation of the northern 
 lights or on true clouds lit up by some reflected light. 
 We quote textualJy, by way of instance, from the 
 notes taken by Br avals at Bossekop • on October 1, 
 1838, during an observation of an aurora borealis. 
 
 ' 11.45. To the north north-west a yellowish light 
 in the form of a flattened arc. Is it a cirro-stratus 
 or an arc? 
 
 ' 11.57. The flattened arc seen at 11.45 is 
 decidedly a cirro-stratus. 
 
 ' Voyages of the Soientifio Commission of the North in Scandi- 
 navia, Lapland, Spitzbergen, and the Faroe Islands during the years 
 1838, 1839, and 1840 on the BechercM. 
 
16 THE POLAE AUEORA. 
 
 ' 12.15. The cirro-stratus in the north north-west 
 still simulates the arc of an aurora. 
 
 ' 1.45. Its form is now clearly defined : the series 
 of cirrus which compose it are nearly parallel, con- 
 verging like the rays of an aurora. 
 
 •2.0. The great cirro-stratus, passing from the 
 north-west to the south-west, has sent towards the 
 zenith a good number of scattered cirri : these seem 
 (if I rightly distinguish these cirrus clouds from the 
 lights of the aurora) to obey the force which directs 
 the rays of the aurora.' 
 
 The analogy of these forms of the aurora with 
 certain clouds is, then, so great that a skilled observer 
 like Bravais hesitates to pronounce upon them, and, 
 after declaring at one moment that they are really 
 clouds that he sees, ends by questioning whether he 
 clearly distinguishes these clouds from the aurora 
 itself. 
 
 The coexistence of these cirrus clouds, with the 
 discs or bands of the aurora has, moreover, been 
 frequently observed. It is well known that the cirrus 
 is formed of little needles of ice, which, refracting 
 the light of the sun or moon, produce the optical 
 phenomena known as halos, parhelia, &c. Now on 
 November 2, 1838, one of Bravais' companions, Lillie- 
 hoeoeck, observed around the moon, during an aurora 
 borealis, the ordinary halo of twenty-two degrees of 
 radius. ' There is,' he says, ' an intimate relation 
 between the light of the halo a,nd that of the aurora, 
 
FORMS OF THE POLAK AUEOEA. 17 
 
 for -where a ray of the latter cuts the halo the ray 
 becomes wider and its light appears more condensed.' 
 We shall' see later the important bearing of observa- 
 tions of this nature on the theory of polar auroras. 
 
 It would be easy to multiply similar quotations, 
 and to show that, not only is it possible to confound 
 the aurora with cirrus, but that the two phenomena 
 are frequently mingled. In the twihght of the dawn 
 cloudy bands have been seen to take the place of the 
 bands of the aurora. At other times arched clouds exist 
 in the sky before nightfall, and it is the aurora, on the 
 contrary, which seems to take their place. The two 
 phenomena may succeed each other or coexist, and 
 it then seems probable that the auroral light allied 
 during the night with the cirrus persists with it in 
 the daytime, although it is no longer possible to dis- 
 tinguish its proper light. 
 
 The auroral patches and bands often exhibit curious 
 variations in brilliancy, and these have been named 
 by Bravais palpitating lights. We wUl borrow as an 
 example the following details from Bravais' observa- 
 tion of October 22, 1838 : ' These are patches of a faint 
 yellow colour, into the centre of which is injected 
 from time to time a brilliant light of a more vivid 
 colour, which lasts but an instant. The patches seem 
 subject to alternate expansion and contraction, which 
 may be compared to the movement of medusae swim- 
 ming in the sea. It is a curious fact that the different 
 patches of light which occupy different parts of the 
 
18 THE POLAE AUEOEA. 
 
 sky undergo simultaneously this alternative move- 
 ment. To the dilatation is added at the same time an 
 increase in the intensity of the light. Independently 
 of this alternative movement the patches undergo a 
 change in form and intensity which is much slower, 
 and does not appear to be periodic. The peristaltic 
 movement generally consists of one or two sharp 
 beats, lasting half a second or so, after which there 
 is a pause of a few seconds, and the beats begin 
 again. Some of the patches are doubled in extent 
 and in brilliancy relatively to their contracted 
 state.' 
 
 The causes to which this palpitation of the light is 
 due may persist for several days. Instead of all the 
 auroral patches of light obeying the same alternative 
 movement, these patches may form part of two series, 
 of which the one palpitates, while the other is com- 
 pletely free from movement. The spots of light in 
 the two series may be so similar, and so much mingled 
 together, that the eye of the observer cannot, during 
 the period of repose, distinguish them the one from 
 the other ; they may perhaps, however, belong to two 
 different planes. 
 
 Sometimes, finally, the obscure phase amounts to 
 total extinction, and as the patches, on reappearing, 
 have not always retained their original position, they 
 resemble ' the clouds of smoke poured forth by a 
 distant locomotive ' (Bravais). 
 
 A cuiious phenomenon, mentioned by Hildebrand- 
 
FORMS OF THE POLAH AUEOEA. 19 
 
 son/ director of the observatory at Upsala, may be 
 connected with this second type of auroras. On July 
 25, 1877, on the south of Lake Wetter, two ob- 
 servers remarked, between two storms which succeeded 
 each other at an interval of three hours, less than 
 two yards above the surface of an arm of the lake, a 
 luminous floating mass of a red colour, transparent 
 and clearly defined, with undulating outlines. It was 
 unmistakably relieved against the other shore of the 
 lake, which was wooded and at a distance of 750 yards. 
 The length of the luminous mass might be about 200 
 yards. Somewhat later a similar light was seen three 
 times : it lasted on each occasion about two seconds, 
 Hildebrandson considers this phenomenon as a tran- 
 sition between the polar aurora and the electric dis- 
 charge of a storm. 
 
 Luminous effects, which are probably also forms of 
 the aurora borealis, have on other occasions been seen 
 very near the ground. The following case is thus 
 described by Arago : ^ — 
 
 'Major Sabine and Captain J. Eoss were returning 
 in the autumn from their first Arctic expedition; 
 they were still in the Greenland seas, during one of 
 the dark nights of those regions, when they were 
 summoned to the bridge by the of&cer of the watch, 
 who had just seen something very strange. This was, 
 
 ' Zeitschrift der Ssterreichm Qesellschaft fiir Meteorologie, vol. 
 xiii. 1878, p. 124. 
 
 ^ Arago, CEuvres computes, vol. iv. p. 146. 
 
20 THE POLAE AUEOEA. 
 
 ahead of the vessel and precisely on their course, a 
 stationary light, which rose to a great height from the 
 surface of the sea, while in all other directions the 
 sky and horizon appeared black as pitch. There was 
 no known danger in those regions, and the direction 
 of the vessel was therefore not changed. When the 
 vessel entered the ciixle of light the whole crew was 
 silent, attentive, on the alert. The highest parts of 
 the masts and sails could then be seen and all the 
 rigging. The meteor appeared to extend for about 
 four hundred yards. When the stern of the vessel 
 left it it was again in darkness ; there was no gradual 
 decline in the intensity of the light. The luminous 
 region could be seen from the stern of the ship for a 
 long time.' 
 
 3. Homogeneous arcs. — In certain regions, and 
 probably also at certain epochs, the polar aurora 
 manifests itself simply as a very regular arc of a 
 circle, with well-defined outlines and uniformly 
 luminous in all its parts, so that it presents an abso- 
 lutely homogeneous texture. It is under this form 
 that the aurora borealis most often presented itself 
 to Professor Nordenskioeld in 1878-79 during the 
 celebrated wintering of the ' Vega ' on the northern 
 coast of Siberia, almost at the entrance to Behring 
 Straits.^ In this station the summit of the arc 
 
 ' Om norrsTcenen under ' Vegas ' oefvemintring vid Berings Sund, 
 1878-79, af A. E. Nordenskioeld. A French translation of this 
 work has been published by M. de Saporta in the Annales de Chimie 
 et de Physique 1884, vol. i. 
 
Fig. 2. — WiKTEBiiJG OF the 'Vega.' Elliptical Arcs. 
 
 ^ ,f"T3««^"'^"-";7''^f5'iieif^ct, 
 
 I'i 
 
 Fig. 3.— Winteeing of the ' Vega.' Elliptical Aecs, 
 
FORMS OF THE POLAR AURORA. 21 
 
 rarely exceeded a height of thirty degrees above the 
 horizon, so that its centre remained well below the 
 horizon. 
 
 These arcs are generally completely motionless 
 and remarkably permanent : they often retain their 
 position for hours and even for several days. As a 
 rule their summit is nearly in the magnetic meridian 
 or the direction indicated by the needle of a compass. 
 We shall recur to this coincidence, which is of great 
 importance. 
 
 It sometimes happens that these arcs, instead of 
 being circular, are distinctly elliptical (figs. 2 and 3). 
 The two curves which constitute its upper and under 
 edges may not be at all points at the same distance 
 from each other; they may be, for instance, two 
 ellipses having the same centre, and of which the axes 
 are unequal ; in this case the width of the arc is not 
 the same at all points (fig. 3) . 
 
 Sometimes, instead of a single circular arc, there 
 are two which are perfectly concentric ; they may 
 even coexist to the number of three or four (fig. 4). 
 A more remarkable and mush more rare case 
 has also been observed by Nordenskioeld, that in 
 which the aurora presents itself in the form of two 
 arcs of which the centres are far apart, so that the 
 arcs cut each other (fig. 5), or even only touch at one 
 foot. But in this case the aurora no longer retains 
 the fixity which characterises the single homogeneous 
 arc : these anomalous forms only last a short time, and 
 
22 THE POLAR AURORA. 
 
 are a transition towards the variable auroras which 
 compose the second class. 
 
 4. Non-homogeneous arcs, or arcs with rays. — The 
 arcs with rays, which constitute the first variety of 
 auroras of the second class, may be developed by 
 insensible degrees from the homogeneous arcs of the 
 third type which we have just described. Instead of 
 being formed of a fixed and even light, they appear 
 to be composed of a great number of fibres or rays of 
 which the direction is perpendicular to the length of 
 the arc. As a rule these rays are more luminous 
 portions detached, not from the dark ground of the 
 sky, but from a paler nebulous arc. If, on the con- 
 trary, the rays are projected on a very dark ground, 
 and if at the same time they are wider than the 
 spaces which separate them, the spaces take in their 
 turn the appearance of rays or black stripes (see 
 fig. 8) : these black stripes are not a distinct 
 phenomenon and have no real existence ; it is only 
 the dark background of sky seen through the narrow 
 interval separating two luminous rays which are very 
 near to each other. 
 
 The transverse rays which compose the arc appear 
 to be parallel to each oth.er if their length is not 
 great ; but if they are sufficiently developed it becomes 
 evident that they really all converge towards a fixed 
 point in the heaven. This point is usually close to 
 the magnetic zenith, that is to say the place to which 
 a suspended and magnetised needle points. It is 
 
Fig. 4.-W1NTBEING OF THE 'Vega.' Multiple Arcs. 
 
 Fig. 5.— Winteeino of the ' Vega.' Multiple Aecs with 
 
 DiPFEEENT CBNTEES. 
 
i^^^^B^ 
 
 Fig. 6. — BossEKop. 
 
 SucoBSsivB Appeaeamobs of the 
 
 SAME AUROEA. 
 
FORMS OF THE POLAR AURORA. 23 
 
 enough for the moment to indicate this fact, to which 
 we shall return when we come to speak of the relation 
 of the aurora borealis to terrestrial magnetism. 
 
 The transverse stripes which compose these arcs 
 are generally clearly defined at the lower end, fol- 
 lowing a more or less regular curve which limits the 
 arc. The upper end, on the contrary, is commonly 
 less distinct ; sometimes the arc is shaded off above 
 and seems to fade into the sky (fig. 6). 
 
 The striped arcs have a less regular form than the 
 nebulous kind, of homogeneous structure, belonging to 
 our third group. Their lower edge often presents in- 
 dentations or waves which the others have not. Yet 
 the mean curve is generally about the same in both 
 cases, and so with their colour, which is usually a yel- 
 lowish white, and rarely shows red or violet tints. 
 
 These arcs generally vary incessantly, as may be 
 seen in fig. 6, which represents five successive stages 
 in an aurora observed at Bossekop (Lapland) by 
 Bravais and Lottin on January 12, 1839. The striped 
 arcs change into more or less homogeneous arcs, or 
 vice versa. Sometimes they seem to melt away at one 
 end ; sometimes they vanish completely to reappear 
 the next moment. At the same time they display the 
 most varied movements ; for instance, they transport 
 themselves from the north to the south, or the south 
 to the north. At other times, again, the height of the 
 arc remaining constant, its feet, that is to say the 
 points at which it touches the horizon, move in direc- 
 
24 THE POLAE AUEOEA. 
 
 tions opposite to each other, as if the whole arc 
 turned round averticalhne from east to west, or from 
 west to east. The rapidity of these movements is 
 very variable : at Bossekop, Bravais and Lottin fre- 
 quently saw arcs rise as much as five degrees a 
 minute ; once an arc changed its place with a rapidity 
 corresponding to seventeen degrees a minute. It will 
 be understood that these movements hamper the obser- 
 vations considerably, and sometimes render it impos- 
 sible to secure accurate measures of the form and the 
 height of these arcs. 
 
 Multiple striped arcs are not uncommon, at least 
 in certain districts. During the 201 days which the 
 French Commission spent at Bossekop, and out of 
 151 on which there were auroras, on one occasion as 
 many as nine arcs were seen at one time ; twice, seven 
 were seen, twice, six arcs, once five, and three times 
 four ; that is, there were nine nights out of 151 when 
 the number of arcs seen at one time was four or more. 
 Triple or double arcs were extremely common. 
 
 Certain rays of the arc have sometimes a great 
 length : this elongation is nearly always from the 
 upper border ; once only, as an exception, the 
 French Commission saw at Bossekop rays starting 
 from the lower border of the arc and pointing to the 
 horizon. This form of arc, from which long rays 
 spring towards the zenith, is one of the finest mani- 
 fested by the polar aurora in France. We give an 
 example in fig. 7, which represents the aurora bore- 
 
FORMS OF THE POLAE AUEOEA. 25 
 
 alis observed at Paris on October 24, 1870 ; an aurora 
 of the same form was again seen at Paris the follow- 
 ing evening. In Mairan's work ' several similar 
 auroras are reproduced, observed at Evreux in 1731. 
 
 Among the different moveme'nts of the striped 
 arc we must mention, in especial, a remarkable undu- 
 latory appearance : the arc seems to move in the 
 direction of its length with great rapidity, which may 
 be as much as forty degrees a second. Bravais, who 
 frequently observed this phenomenon in Lapland, sug- 
 gests the same explanation as Mairan had offered ; i.e. 
 that there is no real movement of the arc, but a suc- 
 cessive lighting up of its different parts, which 
 remain motionless or nearly so. A ray, at first but 
 faintly luminous, becomes suddenly very brilliant for 
 a brief instant and returns to its former state, while 
 the next ray brightens in its turn, and so on from 
 one to another. It is clear that if the successive 
 illumination of the different rays takes place with 
 great rapidity the eye cannot distinguish whether 
 the arc really moves as a whole or whether it is only 
 a sort of luminous wave which passes from one end 
 to the other of the arc. At Bossekop this move- 
 ment appeared twice as frequently from west to 
 east g,s in the converse direction ; certain auroras 
 showed the two movements alternately. 
 
 ' Traiti physigxie et historigue de Vaurore horiale, by M. de 
 Mairan. Paris : Imprimerie royale, 1733. (Extracted from the 
 Memoirs of the Eoyal Academy of Science, 1731.) A second edition 
 of this work appeared in 1754. 
 
26 THE POLAE AURORA. 
 
 An appearance 'which often precedes or accom- 
 panies a great number of auroras, but especially those 
 of the types which we are now considering, is the 
 dark segment, a sort of segment or circle of a darker 
 tone than the rest of the sky, which occupies the 
 horizon to a height of about ten degrees. It is pro- 
 bably this dark segment which the Greeks and Latins 
 compared to the mouth of a cavern, or to a gulf 
 whence issue the fires of heaven ; and it explains the 
 name of gulfs which they gave to auroras, as we have 
 indicated in the history of the phenomenon. . 
 
 When the aurora is in the form of an arc the 
 lower edge of the arc limits precisely the dark seg- 
 ment and seems to rest upon it. The dark segment 
 is not formed by cloud or dense vapour, for the 
 stars are often seen in it. 
 
 The nature of this appearance is not yet well 
 known : the French Scientific Commission at Bosse- 
 kop often had occasion to observe it, accompanied by 
 an aurora borealis, or even alone ; it is not, there- 
 fore, merely an effect of contrast. On the other hand, 
 it is not rare to see polar auroras which are neither 
 preceded nor accompanied by the dark segment ; the 
 two phenomena are thus, to a certain degree, inde- 
 pendent of each other. Basing his opinion mainly 
 on the total absence of the dark segment during a 
 period rich in auroras, but when the serenity of the 
 skies was remarkable, and also on the usual posi- 
 tion of the dark segment beside the Frozen Ocean, 
 
FORMS OF THE POLAE AURORA. 27 
 
 Bravais thinks that the origin of this phenomenon 
 need not be sought elsewhere than in the foggy 
 vapour which generally lies on the horizon near the 
 Arctic Sea. In spite of the weight which is justly 
 attached to the opinion of Bravais, the explanation 
 which he proposes appears at least contestable ; it 
 cannot apply in any case to the numerous observa- 
 tions of the dark segment in stations of which the 
 geographical situation differs markedly from that of 
 Bossekop, and where the neighbourhood of the sea 
 cannot be invoked. On this point there is still much 
 uncertainty, and a great number of observations, 
 made under circumstances of great variety, will be 
 needed to dispel it. 
 
 To conclude the physical description of the 
 auroras in the form of an arc we must note that 
 in the greater number of cases the summit of the 
 arc is in the magnetic meridian, or close to it. 
 This rule is followed with remarkable exactitude in the 
 case of those arcs especially which are not more than 
 seventy degrees above the horizon. Thus at Bossekop 
 102 auroras of this type had at their summit a mean 
 position which did not vary more than six or seven 
 degrees from the magnetic meridian. But marked 
 exceptions occur occasionally. On the night of 
 January 16, 1839, for instance, an arc was observed 
 at Bossekop of which the summit was eighty degrees 
 distant from the magnetic meridian. We shall 
 return to this point later, when we come to con- 
 
28 THE POLAH AUEOEA. 
 
 sider the relations between the polar aurora and 
 terrestrial magnetism. 
 
 5. Auroral rays. Polar crowns. — We have just 
 seen that, in the auroras belonging to the preceding 
 type, rays are often observed which far exceed the 
 limits of the arc. These rays often exist alone, and 
 constitute an important class of auroras. These are 
 luminous columns of which the length is much greater 
 than the breadth, and of which the direction passes, as 
 a rule, not far from the magnetic zenith. The rays 
 which are in the magnetic meridian appear therefore 
 vertical, while the others strike the horizon at an 
 angle. This law of the convergence of the rays on 
 the magnetic zenith is not, however, absolute, for 
 Bravais frequently saw intersecting rays which seemed 
 to pass over each other. 
 
 The dimensions of the rays are very variable : 
 some have a length of only two or three degrees, while 
 others extend over more than half the vault of the 
 sky ; their width is from a fraction of a degree to two 
 or three degrees, rarely exceeding the latter figure. 
 
 The rays are generally distinctly defined along 
 their edges, and this, taken together with the move- 
 ments of which we shall speak directly, distinguishes 
 them from the patches and bands belonging to auroras 
 of the second type. Their light is more brilliant than 
 that of the arcs proper, and may be vivid enough to 
 produce reflections in water or on snow. They are 
 generally more luminous and more definite towards 
 
« 
 
 <1 
 
 a 
 
 El 
 < 
 
 
 a 
 
 H 
 
FOEMS OF THE POLAE AUEOEA. 29 
 
 the foot than higher up. Finally stars may be dis- 
 cerned through the rays as through the arcs. 
 
 Sometimes these rays, very numerous and close 
 together, become fused together, and produce a frag- 
 ment of a striped arc, and even a complete arc ; at 
 other times they form a bundle of rays resembling 
 cirrus clouds or fibres of asbestos. We give drawings 
 " of these groups of fibrous rays from a sketch by M. de 
 la Monneraye. The dark rays, of which we spoke 
 above, may also be distinguished in the illustration 
 (fig. 8) . These groups of rays often change with great 
 rapidity ; the one which we have chosen as an example 
 presented five minutes later the aspect shown in 
 fig. 9. 
 
 Indeed, the special characteristic of the auroral 
 rays is their extreme variability. They are subject to 
 two kinds of movements : the lateral movement, which 
 displaces them in a direction parallel to the horizon 
 from right to left, or from left to right, and the longi- 
 tudinal movement, towards the zenith or towards the 
 horizon. Both movements may be very rapid ; thus 
 Bravais observed on October 11, 1838, a ray which in 
 twenty-seven seconds had covered a distance of ninety 
 degrees, or half the heaven. 
 
 The longitudinal or vibratory movement offers 
 several remarkable peculiarities. Sometimes the ray, 
 remaining nearly in the same place, lengthens itself 
 rapidly towards the zenith, or more frequently towards 
 the horizon; it is then said to dart. Sometimes, 
 
80 THE POLAE ATJROEA. 
 
 without altering sensibly in length, it rises and falls 
 alternately, and is then said ,to play or to dance. This 
 appearance of the aurora, fairly common in some 
 countries, is designated by sixteenth-century authors 
 leaping goats (caprae saltantes) or flying fires ; it 
 probably explains the name of goats bestowed by 
 Aristotle on certain luminous phenomena observed in 
 the sky, as we have said before ; they are still known 
 in Canada as marionettes, and in the Shetland Isles 
 as merry dancers. 
 
 We have said above that the direction of all the 
 rays passes, as a rule, close to the magnetic zenith of the 
 locality. When the rays exist in all directions round this 
 point the result is the rude figure of a crown or glory 
 with rays ; hence the name of boreal crown applied 
 to this particular form. The centre of the crown 
 may be luminous or obscure, according to the prolon- 
 gation of the rays to their point of junction or their 
 arrest at a certain distance. We give, from the 
 drawings of M. de la Monneraye (figs. 10 and 11), the 
 aspect of a boreal crown observed in Newfoundland 
 in the night from September 1-2, 1892. Each of 
 the drawings represents the half of the crown. To 
 obtain an exact idea of the appearance the two 
 drawings must be supposed to be joined together at 
 their upper end, and then curved into the form of a 
 cylinder, the lower part of fig. 10 being to the east, 
 and that of fig. 11 to the west, the observer below, 
 near the axis of the cylinder. 
 
Fig. 10.— Bay or Islands. Eastbbn Half of a Coeona Boeealis. 
 
Fig. 11.— Bat op Islands. Wkstben Haw op a Cokona Borbalis. 
 
FORMS OF THE POLAE AUEOEA. 31 
 
 Sometimes the rays appear only on one side of 
 the magnetic zenith ; the crown is then incomplete : 
 it is not closed, and forms a wreath. When, on the 
 contrary, the crown is complete and furnished with 
 very long rays, which descend almost to the horizon, 
 the aurora forms a dome, which early authors call a 
 tent, pavilion, cupola, &c. Finally, when the centre 
 of the crown remains obscure, and the rays come very 
 low down on aU sides, they form round the horizon an 
 immense luminous band. 
 
 At certain moments the rays which compose the 
 crown enter into rapid movement, become very 
 brilliant, and take on, instead of the yellowish white 
 colour which is habitual to them, vivid tints of red 
 and green. The crown then offers one of the finest 
 manifestations of the aurora borealis. When one of 
 these brilHant crowns forms itself in the midst of an 
 already existing aurora, all the other lights of the 
 aurora pale to reappear again when the crown is 
 dissipated. 
 
 Although rare in low latitudes, the crown may be 
 occasionally observed at a distance from the polar 
 regions. Several examples are known in France ; we 
 have already mentioned the aurora in the form of a 
 crown observed and described by Gregory of Tours ; 
 another, fully developed, which covered the greater 
 part of the sky, was observed by Mairan on October 
 ]9, 1726, and is illustrated in his treatise on the 
 aurora borealis ; a distinct crown was also observed 
 
32 THE POLAB, AUROEA. 
 
 in Paris, October 25-26, 1870. Finally, crowns have 
 also been seen even nearer to the equator, notably 
 that which is represented in fig. 15, which was observed 
 at Melbourne in latitude 38° S. 
 
 6. Auroras in the form of draperies. — We have 
 seen that the rays of the aurora, when they are very 
 numerous and very close to each other, may produce 
 either striped arcs or crowns and wreaths. When 
 the aurora is still more developed, and its form less 
 regular, the appearances it presents are most compli- 
 cated and remarkable, and constitute the finest 
 manifestations of the phenomenon. All the rays are 
 grouped into a wide band, which takes the form of 
 undulating drapery, and suggests the folds of a flag 
 agitated by the wind. 
 
 This type of aurora presents an infinite variety. 
 Sometimes the general form is arched, as in figs. 1 
 (frontispiece) and 12. At others this form disappears 
 entirely, and the aurora really resembles ribbons or 
 drapery (figs. 13, 14, and 18). 
 
 The more brilliant parts appear to be in relief, 
 while others, less illuminated, seem to pass behind or 
 to form the hollows of the folds. In most cases, since 
 there are no means of determining exactly the real 
 form of the aurora and the distance of its different 
 parts from the observer, it is very difficult to decide 
 whether this appearance of reliefs and hollows is not 
 simply an optical illusion, due to the differences in the 
 intensity of the rays. But in certain auroras, such 
 

 
 i 
 
 O 
 
 K 
 
 P 
 
 
FOEMS OF THE POLAR AUEOEA. 83 
 
 as those represented in figs. 12 and 13, it is impossible 
 to doubt the existence of several distinct luminous 
 planes which fold over each other. 
 
 All auroras in the form of drapery, fans, undu- 
 lated arcs, are in general clearly outlined along their 
 lower border, while the light fades out gradually 
 above and mingles insensibly with the sky. They 
 often display the most brilliant colours. The lower 
 part, along the outlined edge, is a brilliant rose 
 carmine, sometimes slightly tinged with violet. This 
 passes into a yellowish white, which occupies as a rule 
 the greater part of the aurora, but which occasionally 
 disappears almost entirely. Above, where the light 
 becomes fainter, a bluish or greenish tint appears. 
 If we add to these colours the effect of the incessant 
 undulatory movement which stirs the aurora we shall 
 be able to form an idea of the splendour to which this 
 phenomenon may attain. 
 
 Sometimes, instead of resembling a wide drapery 
 shaken by the wind, the aurora presents the form of 
 a long ribbon, folded back on itself several times, 
 from the upper edge of which spring rays. This 
 appearance was observed by Whymper in Alaska. 
 
 Finally, a last and most curious modification is 
 that in which the drapery seems to end in a narrower 
 ribbon; this ribbon is nebulous and affects the 
 strangest forms, among which that of a hook (fig. 14) 
 was frequently seen at Bossekop by the members of 
 the French Commission, 
 4 
 
34 THE POLAE AUEOEA. 
 
 CHAPTEE III. 
 
 PHYSICAL CHARACTBEISTICS OF THE POLAE ATJEOEA. 
 
 1. Colours of the polar aurora. — We have already, 
 in the description of the various forms of the polar 
 aurora, indicated briefly the colours which they pre- 
 sent. The most frequent is white, more or less 
 tinged with yellow; it is the only colour of most 
 auroras, especially those of our first three types, 
 which are characterised by a nearly homogeneous 
 texture and relatively slow movements. 
 
 The fainter the light of the aurora, the more 
 the yellowish-white tint becomes milky and difficult 
 to define, a characteristic of all faint light. When, 
 on the other hand, the light of the aurora is vivid, it 
 is distinctly yellow. 
 
 After yellowish white the colour which occurs 
 most frequently is rose carmine ; a few auroras with 
 more or less defined outlines are of this tint, which 
 is, moreover, frequently that of isolated rays. 
 
 The richest in colour of all auroras are, as has 
 been indicated, those which are chiefly composed of 
 rays in rapid movement, such as striped arcs, 
 
M 
 O 
 
 <! 
 
 fi 
 B 
 CM 
 
 m 
 a 
 
 0^ 
 O 
 
 o 
 
 m 
 
 0! 
 M 
 1X1 
 
 
%»& 
 
 I ■ 
 
 i ■ 
 
 
 it 
 
 ».J? 
 
 fc. -^ * ' ^ 
 
 i? 
 
 1^ 
 
 o 
 K 
 
 M 
 
 B 
 
 < 
 PS 
 O 
 M 
 
 < 
 
 a 
 
 H 
 
 <l 
 
 o 
 
 m 
 
 w 
 o 
 
 I 
 
 
 •i w 
 
 U 
 
PHYSICAL CHAEACTEEISTICS OF POLAB AUBOEA. 35 
 
 crowns, wreaths, and draperies. In these cases the 
 central part of the aurora generally remains of a fine 
 brilliant yellow tint, while the two extremities are the 
 one red, the other green. The red is almost always 
 towards the lower part, and also in the direction 
 towards which the ray moves, while the green is above 
 or behind, in regard to the direction of the movements, 
 whether the movement be in the sense of the length 
 of the rays (vibrating movement) or of lateral dis- 
 placement (undulating movement) . If the ray darts 
 or lengthens itself downwards, the lower extremity will 
 be red and the summit green, and these tints will be 
 very brilliant for two reasons : first, because it is the 
 natural order of the colours in a motionless ray; 
 secondly, because it is in this order that they should 
 be found from the direction of the movement. On 
 the other hand, there is no marked coloration and 
 the tint remains of a nearly uniform yellow when the 
 • ray lengthens itself in an upward direction ; for while 
 the red should be developed in the direction of the 
 movement — that is, in the upper part — the upper part 
 of the ray tends, on the contrary, to present naturally 
 a green colour ; hence the two contrary tendencies 
 neutralise each other. The observations of Weyprecht 
 in Franz Josef Land entirely confirm these laws 
 already established by Bravais at Bossekop, and- 
 very few cases are known in which the distribution 
 of colours was reversed. 
 " The red and green tints have a corresponding 
 
36 THE POLAE AUEORA. 
 
 intensity : when the red is very briUiant, so also is the 
 green. The red remains the brighter of the two 
 tints, and is also that which fades last when fog 
 obliterates the aurora by degrees. Independently of 
 the relative intensity of the two tints, the fact that 
 red light penetrates fog more easily than green may 
 have something to do with this. 
 
 In very brilliant auroras the intermediary yellow 
 tint may disappear altogether, and only the red and 
 green remain. This frequently happens in the crown 
 more particularly, of which the centre is then green 
 while the whole periphery is red. 
 
 We have said above that isolated rays are fre- 
 quently entirely red ; it is, on the contrary, very rare 
 to see rays which are entirely green. This pheno- 
 menon only presented itself once to the French 
 Commission during the whole of its stay at Bossekop ; 
 on January 2, 1839, at 8.45 p.m., an arc composed 
 solely of green rays was observed. 
 
 According to some observers it would seem that 
 the green colour is in certain auroras replaced by a 
 blue or violet tint ; but this last colour is extremely 
 rare. 
 
 The brilliancy of the colours of the aurora seems 
 to have a definite relation to the state of the atmo- 
 sphere. In high latitudes particularly, the observa- 
 tions of Sir John Franklin, McClintock, Weyprecht, 
 &c., have shown that the colouring of the aurora is 
 less strong when the air is very pure, and increases 
 
PHYSICAL CHARACTERISTICS OF POLAR AURORA. 37 
 
 when the atmosphere becomes foggy and its trans- 
 parency is diminished. Another circumstance which 
 should be mentioned in this connection is that the 
 auroras in the form of drapery, which are generally 
 the richest in colour, are usually seen only in regions 
 where the seas are open in winter and free from ice, 
 and where, consequently, fogs are of very frequent 
 occurrence ; such are the north of Norway, Spitz- 
 bergen, and Newfoundland. • 
 
 2. Intensity of the light of polar auroras. — The 
 intensity of the light emitted by polar auroras is 
 usually feeble, even in the most brilliant auroras. 
 By the light of a very bright boreal crown, Bravais 
 could hardly read a few words printed in the character 
 known to printers as small text ; it was very easy, on 
 the contrary, to read the same characters by the light 
 of the full moon, of which the apparent dimension is 
 however much smaller»than that of the aurora. The 
 greater number of scientific men who have observed 
 auroras in polar regions, where they are brightest, 
 Parry, Bravais, Kane, Hayes, Weyprecht, Norden- 
 skioeld, agree in the statement that the total illumina- 
 tion produced by the finest auroras is generally inferior 
 to that of the full moon, and rarely exceeds that 
 of the moon in her first quarter. It is clear, then, 
 that on an equal superficial area the brilliancy 
 of the polar aurora is far inferior to that of the 
 moon. 
 
 An indirect proof of this fact is found when we 
 
38 THE POLAR AUEOEA. 
 
 note the periods of the appearances of the aurora. 
 Their frequency always diminishes when the moon is 
 full, which shows that the general illumination of the 
 sky produced by the moon at the full completely 
 drowns a great number of auroras and prevents their 
 being visible. This influence of the age of the moon 
 on the apparent frequency of the aurora borealis had 
 already been noted by Mairan, who found, on an 
 average, three times as many auroras visible in that 
 half of the lunar month which comprehends the new 
 moon — that is, from the beginning of the last quarter 
 to the end of the first — as in the half which com- 
 prehends the full moon, from the end of the first 
 quarter to the beginning of the last. 
 
 There are, however, exceptional auroras which are 
 suf&ciently brilliant to appear such even when the full 
 moon is shining; witness the aurora which was 
 observed all over Central Europe on February 4, 
 1872. It has occasionally been averred that 
 auroras have been seen in broad daylight, but the 
 fact appears to be more than disputable. It is 
 probable that there has' been some confusion between 
 the aurora and certain cirrus clouds which resemble 
 it, and may even be associated with it, as we have 
 already shown. 
 
 Another proof of the faint light given by the 
 aurora is to be found in the facility with which the 
 light of the stars penetrates it, without sensible 
 diminution. "The stars of the first and second 
 
PHYSICAL CHARACTEEISTICS OF POLAR AURORA. 39 
 
 magnitudes may be discerned through the brightest 
 aurora, and when the latter is diffused and milky the 
 visibility of the stars extends to stars of the fourth 
 and even of the fifth magnitudes. 
 
 Nordenskioeld estimates, but without having made 
 any experiments on the subject, that the motionless 
 nebulous arc, which was the almost constant form of 
 the aurora during the wintering of the ' Vega,' might 
 be photographed in fifteen minutes. The sensitive 
 plates which are now prepared would probably reduce 
 this duration to a few minutes. The Swedish expedi- 
 tion which wintered on Cape Thordsen (Spitz bergen), 
 in 1882-83, tried in vain to obtain photographs of 
 auroras. Sophus Tromholt afSrms, on the other hand, 
 that he obtained, with an exposure of eight and a half 
 minutes, a perceptible, though very faint, photo- 
 graphic impression ; it is true that the part of the 
 aurora which he tried to photograph was very faintly 
 luminous. It does not appear that in these attempts 
 ortho-chromatic plates have been used, though their 
 sensibiUty to green and yellow rays is greater than 
 that of ordinary plates. It may, therefore, be hoped 
 that in the near future, by employing ortho-chromatic 
 plates and trying the experiment with brilliant and 
 slow-moving auroras, direct photographs of the polar 
 aurora may be obtained ; this will permit a closer 
 study of its forms and preciser measurements of its 
 dimensions than have hitherto been possible. 
 
 Some observers maintain that the stars scintillate 
 
40 THE POLAE AUEOEA. 
 
 less when they are seen through the light of the 
 aurora than when they shine in a clear sky. But 
 this is probably an error due to the presence of fog at 
 the time of these observations ; for fog diminishes 
 markedly the scintillation of the stars. On the 
 contrary, it is clearly proved that the scintillation 
 increases during an aurora. This fact, announced at 
 the end of the last century by Uscher, has since been 
 verified by Forbes, Necker de Saussure, Kowalski, &c. 
 Finally, Montigny, having invented a scintillometer 
 for measuring the degree of scintillation, has always 
 obtained during the aurora borealis a higher number 
 than before and after. Yet it must not be concluded 
 that it is certainly the light of the aurora which 
 influences _ the scintillation. For Montigny has also 
 discovered that the scintillation increases equally 
 during any magnetic disturbance, even when the 
 latter is not accompanied by any aurora. Now, the 
 auroras during which he noted the scintillation 
 coincided with important magnetic perturbations. It 
 is under these circumstances impossible to decide 
 whether the increase of scintillation must be attributed 
 to the aurora or to magnetic influence. 
 
 Before concluding these remarks on the proper- 
 ties of the light of the aurora, we may add that, 
 according to Argelander, the passage of the light of 
 the stars through the aurora does not alter their 
 apparent positions. 
 
 S. Nature of the light of the aurora. — The nature of 
 
■<1 
 a 
 o 
 « 
 
 < 
 a 
 
 P 
 
 
 
PHYSICAL CHABACTEEISTICS OF POLAE AUROEA. 41 
 
 the light emitted by the polar aurora and its origin 
 may be studied in two dii3ferent manners. 
 
 The first consists in ascertaining whether or no 
 the light of auroras presents any traces of polarisation. 
 Polarisation is a property which luminous rays 
 acquire either by reflection or refraction, and renders 
 them incapable, for instance, of traversing a prism of 
 Iceland spar cut and placed at a suitable angle, or of 
 being reflected from a mirror of glass inclined at an 
 angle of 33° 30' on the rays. By studying any 
 light with apparatus known in optics as analysers, 
 polariscopes, or polarimeters, it is easy to recognise 
 whether this light is natural light emanating directly 
 from a self-luminous body, or whether, on the con- 
 trary, it reaches the eye partially polarised, after 
 undergoing one or more reflections or refractions. 
 
 As early as 1817 Biot studied the light of the 
 aurora borealis in a polarimeter, in the Shetlands and 
 in Scotland ; he could not discover the smallest 
 trace of polarisation. This result has since been eon- 
 firmed by a great number of observers, Macquorn 
 Eankine, Nordenskioeld, &c. On the other hand, 
 Arago and Baudrimont thought they recognised 
 very faint traces of polarisation ; but this can hardly 
 discredit the previous results, for it is sufficient for a 
 cloud to reflect or diffuse the light of the aurora to 
 produce at once traces of polarisation in this reflec- 
 tion or diffusion of the light. The complete absence 
 of polarisation, conclusively established on several oc- 
 
42 THE POLAE AUEOEA. 
 
 casions, is enough to prove beyond a doubt that the 
 Ught of the aurora is not, like rainbows, halos, or 
 parheUa, the result of a phenomenon of reflection or 
 refraction, but that it is itself luminous. 
 
 This important point is confirmed and completed 
 by the results of the spectroscopic analysis. 
 
 If the light emanating from a solid or liquid in- 
 candescent body be passed through the spectroscope, 
 the resulting spectrum is continuous. If, on the 
 contrary, the source of light is gaseous, the spectrum 
 is composed of a certain number of bright lines or 
 stripes, separated from each other by dark intervals. 
 The number, the position, and the brilliancy of these 
 bright lines depend on the chemical composition of the 
 incandescent gaseous body, and this allows us to 
 recognise by the spectrum alone the physical state 
 and the chemical nature of the luminous body under 
 observation. 
 
 The spectrum of the aurora borealis, studied for 
 the first time by Angstroem in 1866, is essentially a 
 spectrum of lines; the light of the aurora is the 
 product, therefore, of luminous gases, and not of solid 
 or liquid incandescent particles; neither can it be 
 due, as has sometimes been supposed, to a reflection 
 of the light of the sun. Among the authors who 
 have studied this question we may mention, after 
 Angstroem, Struve, (Ettingen, Winlock, Zoellner, 
 Vogel, Eand Capron, Norman Lockyer, Barker, 
 Backhouse, A. Clarke, Wijkander, Lemstroem, and 
 
PHYSICAL CHAEACTEEISTICS OF POLAE AUEOEA. 43 
 
 lastly Carlheim Gyllenskioeld.' We will indicate the 
 principal results of their researches. 
 
 Seen through a spectroscope of small dimensions, 
 the spectrum of the aurora borealis is a single 
 greenish-yellow line, placed between the two lines d 
 and E of the solar spectrum. But if a large equatorial 
 is used, so as to collect a great deal of light, and a 
 spectroscope of great dispersive power, as many as 
 thirteen or fourteen lines or luminous bands can be 
 distinguished in the spectrum of the aurora. The wave 
 length of these bands, expressed in millionths of a 
 millimetre, is given in the accompanying table. ^ 
 
 All these lines do not exist simultaneously in the 
 auroras ; the brightest and most frequently seen, at 
 least in polar regions, are 4, 7, 8, 10, and 13. The 
 red line 1 has not yet been seen in high latitudes, 
 although the red colour is frequent in them. The 
 yellowish-green line, 4, is the brightest of all ; it is 
 absolutely characteristic of the polar aurora ; it is 
 often seen alone when the aurora is faint ; it is even 
 
 ' See on this branch of the subject : G. Eayet, on the ' Spectra of 
 the Aurora Borealis,' Journal de Physique Thiorique et Appliquie, 
 vol. i., 1872, p. 363 (a summary of the researches of Angstroem, 
 Struve, Winlock, Zoellner, Vogel, CEttingen) ; Angstroem, ' Of the 
 Spectrum of the Aurora Borealis,' Journal de Physique Thiorique et 
 AppUquie, vol. iii., 1874, p. 210 ; Band Capron, Aurorce and their 
 Spectra, London, 1879 ; Lemstroem, L'Aurore Boriale, Paris, Gau- 
 thier-Villars, 1886. 
 
 ^ Most authors reproduce these lengths of wave in four figures ; 
 this approximation appears to us to be purely illusory, for very 
 often one cannot be sure even of the third figure, the measures 
 being very difficult in the case of a phenomenon so faintly luminous 
 and so mobile as the aurora borealis. 
 
44 
 
 THE POLAR AURORA. 
 
 distinctly visible when the aurora is so faint as to 
 be imperceptible to the naked eye. 
 
 Table of the Lines m the Spectrum of the Aurora. 
 
 
 Length of Wave 
 
 
 Order 
 
 (millionths of a 
 millimetre) 
 
 Colour and Position 
 
 1 
 
 630 
 
 Red, between c and d 
 
 2 
 
 578 
 
 Yellow, between d and e 
 
 3 
 
 566 
 
 Yellow, between d and e 
 
 4 
 
 557 
 
 Greenisli yellow, between d and e 
 
 5 
 
 535 
 
 Green, between n and e d and e 
 
 6 
 
 529-526 (band) 
 
 Green, very near e 
 
 7 
 
 623 
 
 Green, between e and b 
 
 8 
 
 500 
 
 Greenish blue, between b and f 
 
 9 
 
 485 
 
 Blue, very near f 
 
 10 
 
 470 
 
 Blue, between f and a 
 
 11 
 
 464 
 
 Blue, between r and o 
 
 12 
 
 436 
 
 Blue, between p and a 
 
 33 
 
 426 
 
 Violet, between G and h 
 
 14 
 
 411 
 
 Violet, near h. 
 
 The lines 10, 11, 12 and 13 become nearly 
 invisible in those parts of the aurora which give the 
 red line (No. 1) to the spectroscope. Finally, the last 
 line (No. 14) has only once been seen, in Lapland by 
 Lemstroem and under unfavourable circumstances ; 
 the figure which indicates its length of wave is there- 
 fore more uncertain than in the case of the other lines. 
 
 There has been much discussion about the coinci- 
 dences which may exist between these lines and those 
 of known spectra — for instance, the spectrum of the 
 electric spark in gases rarefied like those of Geissler's 
 tubes ; but no very definite conclusion has yet been 
 arrived at. The lines 10, 12, and 13 appear to o,ccur 
 also in the spectrum of the electric discharge passing 
 
PHYSICAL CHAEACTEKISTICS OF POLAE AUROEA. 45 
 
 through dry rarefied air ; in this spectrum are also 
 lines near to 5, 7 and 8, though absolute coincidence 
 cannot be affirmed. For the other lines the uncer- 
 tainty is yet greater. New researches are therefore 
 needed to clear up this question, which is the subject 
 of much controversy. 
 
 The study of the spectra of lightning seems to 
 furnish an argument favourable to the hypothesis 
 which attributes to atmospheric air a certain number 
 of the lines in the spectrum of the aurora. According 
 to the observations of Herschel, Saussure, Vogel, 
 C. Gyllenskioeld, &c., the spectrum of lightning gives 
 seven brilliant lines, of which the length of wave is 
 respectively 630, 569, 534, 526, 500, 486, and 463. 
 These lines are very near to the lines 1, 3, 5, 6, 8, 9 
 and 1 1 of the aurora ; for some of them the coinci- 
 dence appears to be exact. 
 
 In spite of these arguments opinion is still divided. 
 While certain authors recognise no analogy between 
 the spectrum of the aurora and that of the air, others, 
 on the contrary, consider that the resemblance is 
 sufficient. Angstroem, for instance, considers that the 
 spectrum of the aurora is composed of two distinct 
 parts; on the one hand all the lines, except the 
 fourth (length of wave, 557), form a first spectrum, 
 that of rarefied air ; the conditions of pressure and 
 temperature, very different in nature from those in 
 laboratories,- sufficing to explain all divergencies, 
 although Angstroem does not believe in the varia- 
 
46 THE POLAB AUEORA. 
 
 bility of the spectra of gases. The characteristic 
 yellow line (No. 4) constitutes in his opinion a special 
 spectrum. This line has not been found in any 
 known body ; ' Angstroem attributes it to a phe- 
 nomenon of phosphorescence, or rather of fluores- 
 cence. Oxygen, as well as several 6f its combinations, 
 is known to be phosphorescent. Moreover, the light 
 of the polar aurora is certainly rich in ultra-violet 
 rays capable of producing fluorescence; a drop of 
 sulphate of quinine has been made luminous by the 
 action of the rays of the aurora borealis, and so also 
 the double cyanide of platinum and potassium. 
 
 It wUl be seen from the foregoing summary that 
 the light of the polar aurora is not yet clearly known, 
 notwithstanding all the researches bestowed upon it. 
 It is one of the most regrettable lacunae in the theory 
 of the phenomenon, and the one to which the attention 
 of observers should be most directed. It would be 
 desirable to undertake in the laboratory a series of 
 experiments on the spectrum of the electric spark in 
 rarefied air, varying as far as possible the conditions 
 of temperature and pressure, and also those of the 
 discharge itself. 
 
 4. Sound of the aurora. — Another physicar phe- 
 nomenon about which there is considerable disagree- 
 ment is the sound which, according to some 
 observers, sometimes accompanies the aurora borealis. 
 
 • We ehall see later that this line of unknown origin occurs also 
 in the spectrum of the zodiacal light. 
 
PHYSICAL CHAEACTEEISTICS OF POLAE AURORA. 47 
 
 It is a very general belief in certain countries— for 
 instance, in the Orkneys, in Finmark, and among the 
 Indians of the territories round Hudson Bay— that 
 the aurora is accompanied by a particular sound, 
 somewhat resembling the rustling of silk. The 
 Lapps, who also believe in the existence of this sound, 
 compare it to the ' cracking ' which may be heard in 
 the joints of the reindeer when in movement. A 
 great number of trustworthy observers maintain that 
 they have distinctly heard this sound during very 
 vivid auroras. Others, on the contrary, have never 
 remarked any sound which in their opinion could 
 reasonably be attributed to the aurora ; we must note, 
 however, that purely negative results cannot be set 
 against a single positive and certain fact. 
 
 The members of the French Commission of 
 Bossekop, from whose work we have already borrowed 
 so much, did not neglect this question. Once, for 
 instance, on January 10, 1839, during a very brilliant 
 aurora, Bravais notes : ' I listened with much care for 
 possible sounds ; the circumstances were favourable, 
 the air and sea calm, yet I only heard a very^ faint 
 whistling sound, coming I knew not whence, but with- 
 out doubt independent of the aurora, since it was 
 continued after the latter had faded.' 
 
 At another time, October 31, 1838, the sound 
 appears to have been more distinct, for Lottin notes 
 as follows : ' At one moment I, by an instinctive 
 movement, took my cap off to hsten better, fancying 
 
48 THE POLAE AUEOEA. 
 
 that the rays darting above our heads made a sort of 
 crackling sound ; perhaps the sound was due to the 
 distant steps of some one, perhaps of some animal on 
 the hardened snow. M. Siljestroem, at some distance 
 from me, close to his house, had the same illusion at 
 exactly the same hour.' Finally, Thomas, a mining 
 engineer at Kaafiord, near Bossekop, who made at the 
 same time as the French Commission very complete 
 observations of the aurora borealis, notes on March 
 10, 1840 : ' A noise resembling the rustling of straw 
 was distinctly audible, and seemed to coincide with 
 the darting of the rays of the aurora. This sound 
 was only heard when the rays were near the zenith.' 
 
 In spite of these observations, which appear to be 
 very definite, the members of the French Commission 
 pronounced rather against the existence of any sound 
 proper to the aurora. ' Although I dare not,' says 
 Bravais, ' question the validity of the testimony in 
 regard to it, we must yet conclude that this sound is 
 very rare. Moreover, during these observations the 
 ear may be deceived by more than one source of error 
 against which it is impossible to be too much on one's 
 guard ; such are the whistling of the wind, the drift- 
 ing of the dry snow, the distant murmur of the sea, the 
 crackling of snow which begins to freeze again after a 
 temporary thaw, &c.' Siljestroem, one of Bravais' 
 companions, concludes in almost identical terms. 
 
 It is certain that the causes of error are very 
 numerous, and that the observer may be tempted to 
 
PHYSICAL CHAEACTEEISTICS OF POLAE AURORA. 49 
 
 attribute to the aurora many sounds which have 
 nothing to do with it, among which we may mention 
 as a principal one in polar regions the incessant 
 crackling of fields of snow, and the faint sounds which 
 always accompany the formation of small needles of 
 ice on clear, cold nights. Much more should we 
 reject without hesitation the observations on the 
 sound of the aurora which have been taken in the 
 centre of towns, beginning with that of Messier, who 
 claimed to have heard the sound of the aurora in 
 1762, in the very heart of Paris. But, on the other 
 hand, it seems very difficult to discredit altogether 
 not only the general opinion of almost all the dwellers 
 in the arctic regions, but also and especially a mass 
 of testimony from competent observers. 
 
 It would even appear that this sound is audible in 
 much lower latitudes than that of Lapland. The 
 astronomers Brorsen and Hansteen were both abso- 
 lutely convinced of the reality of such a sound. J. E. 
 Schonfeldt affirms that he also heard it in Livonia, 
 September 20, 1839, in absolutely still weather, in a 
 treeless plain covered with wheat, and far from any 
 water, so that the causes of any disturbing sound were 
 eliminated as far as possible ; the sound accompanied 
 the rays, which darted towards the zenith. In spite 
 of the neighbourhood of the sea, a keeper of the hght- 
 house on Sumburgh Head, in the Shetland Isles, was 
 so well able to distinguish the sound proper to the 
 aurora, that once, being in a room v/ith closed 
 5^ 
 
50 THE POLAE ATJEOEA. 
 
 shutters, he became aware of the existence of an 
 aurora from this indication alone. We must add to 
 these observations that of the aeronaut Eolher, who, 
 having left Paris, then besieged by the Prussians, on 
 November 20, 1870, in a balloon, disembarked in 
 Norway. He heard a persistent sound the whole 
 time that he was in a certain cloud, which emitted a 
 strong odour very irritating to the bronchial tubes, 
 like that of ozone. A fine aurora borealis was ob- 
 served at precisely that time. 
 
 Amid these contradictory statements it is well to 
 be cautious, more especially as the great majority of 
 travellers in the arctic regions have never heard the 
 sound of the aurora. 
 
 To the external sources of error already mentioned 
 must be added another, purely physiological : many 
 persons hear a whistling in their ears, which under 
 ordinary circumstances does not reach their conscious- 
 ness. Perhaps this sensation is more vividly perceived 
 when the attention is strongly directed to the observa- 
 tion of an aurora, especially when a ray is seen to 
 shoot out suddenly, to which is referred instinctively 
 a sensation of which the true source is purely sub- 
 jective. 
 
 From the foregoing observations we conclude that 
 it must not be considered as proved, but merely as 
 possible, that during very vivid auroras a sound is 
 produced analogous to the rustling of silk, to that 
 which accompanies the sparks in an electric discharge, 
 
PHYSICAL CHAKACTERISTICS OF POLAE AUEOEA. 51 
 
 or, finally, to the characteristic sound of the fire of 
 St. Elmo so often observed on high mountains, such 
 as the Pic du Midi. In any case it is still an open 
 question. 
 
 5, Odour of the aurora.— The belief in the sound 
 of the aurora rests perhaps in the mind of some 
 people less on facts than on the analogy which exists 
 between the aurora and the electric spark. It is 
 probably, again, this analogy which has led some 
 observers to think that they detected a particular 
 odour at the time of certain auroras. Bergmann 
 compared this odour to that of sulphur, Trevelyan to 
 that of electricity (?) ; lastly, during the aurora of 
 April 5, 1870, Sonrel at Paris and Eedenbacher at 
 Dinkensbiihl in Bavaria, thought simultaneously that 
 they perceived a peculiar acrid odour. But these ob- 
 servations were made in the centre of Europe — that is, 
 at a distance from the seat of the phenomenon — and 
 in towns, where every species of odour abounds, 
 thus taking away almost all value from the result. 
 Up till now no traveller in arctic regions has mentioned 
 a particular odour as prevailing during the aurora, 
 even in cases when, as we shall see, the aurora was 
 certainly very near the earth. It does not seem, 
 therefore, that we are bound to reserve our opinion on 
 this point as on that of the sound of the aurora ; no 
 observation, made under conditions which inspire 
 confidence, confirms the supposition that a particular 
 odour accompanies the polar aurora. 
 
52 THE POLAR AUEOEA. 
 
 CHAPTER IV. 
 
 EXTENT, POSITION, AND FEBQUENCY OF THE POLAR 
 ACIEORA. 
 
 1. Extent of the auroras. — The extent of auroras 
 is very variable : some are purely local phenomena, 
 visible only within a narrow radius ; others, on the 
 contrary, are visible simultaneously throughout a wide 
 area. 
 
 Local auroras appear to be more frequent in high 
 latitudes, where alone the data in regard to them are 
 certain. We have some valuable information on this 
 head ; unfortunately it is still insufficient, for these 
 observations are of capital importance to the theory 
 of the phenomenon. 
 
 During the winter of 1872-73, three polar expe- 
 ditions were established in the arctic regions, and at 
 points relatively near to one another. A Swedish 
 mission, with Palander and Wijkander, was then 
 wintering in the north of Spitzbergen, at Mossel Bay ; 
 at the same time the Austro-Hungarian polar expedi- 
 tion, on board the ' Tegetthof,' with Payer and Wey- 
 precht, was ice-bound less than 800 miles to the east 
 of Mossel Bay ; lastly, Tobiesen was taking observations 
 
EXTENT, POSITION, AND FEEQUENCY. 53 
 
 at the Island of the Cross in the archipelago of Nova 
 Zembla, at about 180 miles south of the ' Tegetthof.' 
 Out of 100 days on which the Swedish mission 
 observed auroras at Spitzbergen, there were, it is true, 
 eighty-three on which auroras were also seen from the 
 ' Tegetthof ' ; but a comparison of directions, and of 
 the hours at which the aurora was seen at the two 
 stations, shows that there was seldom any coincidence ; 
 very frequently nothing was seen from the ' Tegetthof ' 
 when there was an aurora over Spitzbergen, and vice 
 versa, although the atmospheric conditions were 
 favourable. Tobiesen, who was even nearer the 
 ' Tegetthof,' observed thirty-five auroras on days when 
 Weyprecht also saw them ; but, on the other hand, he 
 notes three which were completely invisible to the 
 Austro-Hungarian expedition, although the distance 
 between the two stations was only 250 kilometres. 
 
 So also the ' Alert ' and the ' Discovery,' the two 
 ships of the English polar expedition under Captain 
 Nares, wintering in Smith Strait in 1874-75 at a 
 distance of seventy-five miles from each other, only 
 seven times observed a coincidence in their notes of 
 the aurora borealis. 
 
 We shall give other examples, when we come to 
 discuss the observations relating to the height of 
 auroras, of the local character of many manifestations 
 of the phenomenon. 
 
 In contrast to these local auroras there have been 
 others, especially in lower latitudes, which were visible 
 
54 THE POLAE AUEOEA. 
 
 simultaneously over a very wide area. In the night of 
 August, 28-29, 1859, for instance, the same aurora 
 borealis was seen at the same time over the whole 
 of Europe, in the west of Africa, on the Atlantic, 
 in the whole of North America, and as far as Cuba. 
 The limit of visibility was marked by a line passing 
 from California a little south of Sacramento; it 
 crossed the United States, passing to the south of 
 Jamaica, and ended at St. George d'Elmina on the 
 coast of Guinea. 
 
 Four days later, on the night of September 1-2, 
 1859, another aurorawas visible over the wholeof North 
 America ; its limit of visibility included Guadeloupe, 
 Jamaica, Cuba, and the Sandwich Isles. At the time 
 of this aurora it was broad day in Europe, and this 
 probably is the only reason it was not observed here ; 
 for it manifested its presence very clearly by magnetic 
 disturbance and considerable interruptions in the 
 telegraphic service, phenomena which have an un- 
 doubted connection with the aurora borealis, as we 
 shall show later. 
 
 Perhaps the most remarkable fact in connection 
 with these auroras of wide extent is that they are often 
 produced simultaneously in both hemispheres. During 
 the two great auroras of 1859 mentioned above, very 
 remarkable auroras were also observed in Australia 
 and at Santiago in Chili. It was the same with the 
 great aurora of February 4, 1872. At that date 
 an aurora borealis was observed in the immense 
 
EXTENT, POSITION, AND FREQUENCY. 55 
 
 zone limited on the north by a line drawn from 
 lenisseisk in Siberia to the Bay of Polaris, at the 
 northern extremity of Greenland, and to the south by 
 another line passing through Bombay, Syene (Upper 
 Egypt)) and Florida. This zon.e thus included a great 
 part of Asia, the whole of Europe, and the north of 
 Africa and of the Atlantic. Just at the same hour an 
 aurora australis was visible over a great part of the 
 southern hemisphere, notably in Australia, Mauritius, 
 Eeunion, and Natal. The regions of visibility of the 
 two auroras were thus separated only by a zone of 
 about twenty degrees of latitude on either side the 
 equator. 
 
 It would even seem that this simultaneity of the 
 aurora borealis and australis is the rule and not the 
 exception. Data with regard to the southern hemi- 
 sphere are often wanting, yet we possess an uninter- 
 rupted series of eight years of observations taken at 
 Hobart Town in Tasmania, from 1841 to 1848, during 
 which thirty-four auroras were reckoned. Now, every 
 time that an aurora was seen at Hobart Town an 
 aurora borealis was observed in the northern hemi- 
 sphere, or, at least, if it were day-time in Europe, there 
 were those important magnetic perturbations which 
 accompany polar auroras. 
 
 If it be remembered that the presence of the sun 
 above the horizon prevents a given aurora from being 
 seen over half the surface of the globe, and if we remark 
 that, in the cases cited above, the aurora was seen in 
 
56 THE POLAE AUEOEA. 
 
 the whole of that part of the mean latitudes of the 
 globe where it was night at the time of its appear- 
 ance, it will not seem unreasonable to admit that 
 at certain moments the lights of the double polar 
 aurora may entirely envelop the earth, with the ex- 
 ception of an equatorial zone of a width of about forty 
 degrees. 
 
 This wide extent contra.sts strangely with the very 
 restricted area of other auroras, of which the limit of 
 visibility is some few hundreds of square miles. It 
 seems difficult to attribute the two phenomena to the 
 same cause. We shall see that subsequent considera- 
 tions lead to the same conclusion, and that we must 
 separate entirely the great auroras, visible in low 
 latitudes and occurring but rarely, from the very 
 frequent and quite local auroras which are seen 
 mainly in polar latitudes. 
 
 2. Height of the aurora. — It is more than a century 
 since the earliest attempts were made to measure the 
 height above the surface of the earth of the luminous 
 phenomena which constitute the aurora. They date 
 from 1726, and are the work of Mairan. Before his 
 time it was believed that the seat of the aurora was 
 very near the earth, an opinion founded not on precise 
 data, but solely on the rapidity of the movements of 
 the rays and of the form of the aurora — a rapidity 
 which it seemed impossible to reconcile with any great 
 distance. 
 
 The method proposed by Mairan to determine the 
 
EXTENT, POSITION, AND FEEQUENCY. 57 
 
 height of the aurora has been employed since by most 
 observers, with certain modiiications in detail. It 
 consists in measuring at the same moment, from two 
 stations at a sufficient distance apart, and of which 
 the distance from each other is exactly known, the 
 angular height of a given point of the aurora above 
 the horizon, and its azimuth. A simple calculation in 
 trigonometry then gives, as in ordinary triangulation, 
 the absolute height of the aurora above the horizon, 
 and its distance from the two stations. 
 
 This process, which is very simple in theory, is, 
 however, extremely difficult of application. First of 
 all it is essential that the observers should choose 
 exactly the same point in the aurora ; and it is also 
 necessary, on account of the rapid movements of 
 most auroras, that there should be an absolute 
 simultaneity of the two observations. This last 
 condition is now comparatively easy of realisation, if 
 the two stations are connected by telegraph or 
 telephone. But it may be said that the first condition 
 is never realised. For an aurora does not present 
 distinct marks, easily recognisable from the two 
 stations, such as those which are used in surveying ; 
 even at a slight distance the effects of perspective 
 completely modify the aspect of an aurora. To 
 eliminate this source of error it has been proposed to 
 choose that point of the lower border of the arc which 
 is in the vertical plane of the two stations ; this method 
 would give a satisfactory result if the lower border 
 
58 THE POLAR ATJEOEA. 
 
 were clearly defined, and if the aurora were reduced to 
 thin film. Bat nothing authorises this last hypothesis ; 
 on the contrary, it is certain that the aurora has a 
 considerable depth, so that its lower border, or what 
 appears such to each station, corresponds in fact, as 
 a result of perspective, to different points. And, 
 farther, the lower edge, which is always the clearer, is 
 yet itself always a little softened off ; what is taken 
 for the edge is the point where the light is most 
 intense — that is to say, which corresponds to the visual 
 ray which meets the luminous mass at its greatest 
 thickness. Now, it is certain that these visual rays do 
 not coincide for the two stations. There is, then, very 
 little likelihood that the points of the aurora chosen 
 at two stations even at no great distance from each 
 other will be the same ; we shall find manifest proofs 
 of this in the discussion of certain observations. For 
 all these reasons we must guard ourselves against 
 attributing to the figures obtained for the height of 
 auroras an exactitude which they cannot possess. 
 There is a margin of possible error which in some 
 cases attains to as much as half the numbers given. 
 These are not, properly speaking, measures, but indica- 
 tions of approximate size and distance. 
 
 The first results attained by Mairan were quite 
 contradictory to the then received opinion. Instead of 
 finding that the aurora was at no considerable height 
 above the surface of the earth, he always found the 
 contrary : 266 leagues for the aurora of October 19, 
 
EXTENT, POSITION, AND FREQUENCY. 59 
 
 1726 ; 250 leagues for that of October 8, 1731 ; 160 
 leagues for a sort of coloured shield which was 
 observed during the aurora of February 15, 1730, &c. 
 Mairan hence concludes, from all the measures that he 
 was able to make, that the auroras seen in France in 
 his time were situated at heights comprised between 
 100 and 300 leagues. 
 
 More recent observations taken in Europe lead to 
 similar results. Thus, from an analysis of aU the 
 observations collected about the great aurora of 
 October 25, 1870, Floegel ' deduces the following 
 conclusions : the altitude of the base of the rays is 
 very variable ; it is usually comprised between 150 and 
 250 kilometres (93 to 155 miles), but its extreme 
 limits attain perhaps 100 and 300 kilometres (62 and 
 186 miles). As to the summits of the rays, they 
 often reach a greater height than 500 kilometres (310 
 miles) ; it is even probable that they pass 750 kilo- 
 metres (565 miles) ; but they appear never to reach 
 1,500 kilometres (930 miles). 
 
 However large these numbers may appear, they 
 are not physically impossible, for falling stars have 
 been seen of which the height was certainly some 
 hundreds of kilometres, which proves that at these 
 enormous altitudes there is still an appreciable 
 quantity of air. 
 
 All the measures taken, up to this day, of auroras 
 
 ' Zeitschrift der Gsterreichischen GeseUschaft filr Meteorologie, 
 vol. vi. 1871. 
 
60 THE POLAE AUEOEA. 
 
 in mean latitudes have given similar results. Thus 
 observations of the aurora of October 22, 1804, at 
 Berlin and Halle gave Gilbert a height of 377 kilo- 
 metres, or 223 miles ; it is true that, according to 
 observations taken in Sweden, Baron Wrede estimated 
 the height of the same aurora at 1,313 kilometres, or 
 815 miles, nearly four times as high — a fact which 
 justifies our remark on the untrustworthy nature of 
 these figures. 
 
 Other observations, made in England, and com- 
 pared by Dalton, Cavendish, Potter, Airy, &c., have 
 given numbers varying between 80 and 160 kilometres 
 (fifty to ninety-three miles). 
 
 Loomis ' has also determined the height of the two 
 auroras observed in the United States in 1859, one 
 on August 28, the other on September 2. These two 
 auroras appeared to shine in the zenith at the more 
 northern stations, whereas they were only some few 
 degrees above the horizon in the most southern 
 stations. A comparison of the observations gave 
 seventy kilometres as the height of the lower edge of 
 the arc of the first aurora, and numbers varying from 
 twenty-three to seventy-five kilometres for the second. 
 The upper edge had a height of 800 kilometres in the 
 first case, and 730 kilometres in the second. 
 
 Observing all necessary caution as to the accuracy 
 of these numbers, it is yet certain that all the obser- 
 
 ' E. Loomis, ' The Aurora Borealis,' Reports of Smithsonian 
 Institution, 1865. 
 
EXTENT, POSITION, AND PEEQUENCY. 61 
 
 vations agree sufficiently to show that in mean 
 latitudes the height of the aurora is considerable ; it 
 appears rarely to be less than seventy or eighty kilo- 
 metres for the lowest part of the aurora, while the 
 summit sometimes attains several hundred kilo- 
 metres. 
 
 The French Commission, during its stay at 
 Bossekop, made many measurements of the height of 
 the aurora. Bravais and Lottin observed simultane- 
 ously at Bossekop and Jupvig, at a distance of about 
 sixteen kilometres, or ten miles from each other. In 
 spite of all the difficulties which they encountered, 
 they thought they might conclude from the sum of 
 their measures that the mean height of the arcs of the ■ 
 aurora borealis at Bossekop is from 100 to 150 kilo- 
 metres above the surface of the earth. If we examine 
 their observations in detail we shall see that in a 
 certain number of cases they found for the parallax 
 of the aurora, or the difference of the apparent 
 heights above the horizon, a negative number ; that 
 is to say that the aurora, although seen towards the 
 north, presented at the northern station a less 
 apparent height than at the southern station, which is 
 manifestly impossible. This result can only be ex- 
 plained, as we have already shown, in one way : the 
 observers saw the aurora under different forms, and 
 really chose two different points. 
 
 Bravais has indicated another method for measur- 
 ing the height of auroras, which requires only one 
 
62 THE POLAE AtTEORA. 
 
 observer, but necessitates, on the other hand, an 
 hypothesis which is at least disputable. This second 
 method consists in measuring the apparent width of 
 the auroral bands, which pass through the zenith, at 
 their summit and at their foot. If we then assume 
 with Bravais that the auroral band is parallel to the 
 surface of the earth — that is to say, that all parts of it 
 are at the same height— it is easy to calculate, accord- 
 ing to the laws of perspective, the apparent variation 
 in width which the band should present at its different 
 points, and its absolute height above the earth. 
 Bravais used this method as a verification of the first ; 
 the results were nearly in agreement with the others ; 
 therefore Bravais thought he might consider it as 
 proved that ' the height of the arcs of the aurora 
 borealis is as a rule between 100 and 200 kilojnetres 
 above the surface of the earth.' 
 
 In the article from which we have already quoted 
 on the auroras observed during the wintering of the 
 ' Vega,' Nordenskioeld has calculated the height of the 
 homogeneous arc, which was the almost constant 
 form of the aurora in that district and at that 
 time, by an indirect method which is something like 
 Bravais' second plan. He measured only the 
 angular height of the summit of the arc and the 
 opening of the arc, or width of the angle of the two 
 points where the arc cuts the horizon. To make the 
 calculation with these data only, Nordenskioeld 
 assumes that the arc is circular, and situated in a 
 
EXTENT, POSITION, AND PREQUENCY. 63 
 
 plane perpendicular to the radius of the earth which 
 terminates in a point near the magnetic pole (lat. 80° 
 N., long. 83° west of Paris). He concludes that the 
 plane which contains the auroral arc, and which is 
 perpendicular to this radius, cuts it at a distance of 
 125 kilometres below the surface of the earth. In 
 this plane the ring of auroral light would have its 
 lower edge at about 200 kilometres above the surface 
 of the earth. 
 
 The hypothesis of Nordenskioeld requires more 
 confirmation. But it will be seen that it leads, with 
 regard to the height of the aurora, to a conclusion 
 similar to that arrived at by other methods. 
 
 In contradiction to all these observations which 
 assign an enormous height to the aurora borealis, we 
 might quote many others which lead to results entirely 
 different. 
 
 Farquharson, who had organised corresponding 
 observatories in different parts of Scotland, found 
 that the auroras often illuminated the lower surface 
 of the clouds. In particular, simultaneous observa- 
 tions taken on December 20, 1829, at Alford and 
 Tyllynessle, assign an altitude of only 1,220 metres, 
 or very nearly 4,000 feet. From observations in the 
 Shetland and Faroe Isles, Trevelyan believes that the 
 aurora often descends to fifteen metres only (fifty feet) 
 above the sea-level. 
 
 Parry and two of his companions observed at Port 
 Bowen, on January 27, 1825, a ray of the aurora 
 
64 THE POLAE AUEOEA. 
 
 borealis projected between their ship and the shore, 
 which was about a mile and three-quarters 
 distant, and reached an altitude of about 670 feet 
 only. Eoss and Scherer also mention several times 
 auroral rays interposed between their two ships, or 
 between the ships and icebergs. Finally, Sir John 
 Franklin and many others affirm that they have 
 seen the under surface of clouds lit up by the aurora, 
 which certainly shone between these and the earth. 
 
 Similar appearances were observed by the French 
 Commission in Lapland. During the aurora of 
 September 20, 1838, Bravais notes : 'A very large ray 
 to the south-west ; it is evidently lower than the 
 clouds. These clouds are clearly coloured from 
 below ; the hghts are lower than the clouds.' Later, 
 on October 31, Lottin observes a ray of the aurora 
 between him and the mountains. Nevertheless, in 
 spite of his own assertions, Bravais, in the general 
 summary of his observations, explains these appear- 
 ances as optical illusions. He attributes, for instance, 
 the prolongation of the rays in front of a mountain to 
 the reflection of the light of the snow crystals, and 
 finally rejects the hypothesis of the proximity of the 
 aurora, doubtless because it was in open contradiction 
 with the results of his direct measurements as given 
 above. 
 
 Since this date the most skilled observers of this 
 class of phenomena have collected a great number of 
 data which place the matter beyond a doubt. 
 
EXTENT, POSITION, AND PEEaUENCY. 65 
 
 Lemstroem,' during the Swedish expedition to 
 Spitzbergen of 1868, several times saw auroral lights 
 projected between him and the mountains situated at 
 a short distance ; these hghts, studied in the spectro- 
 scope, showed moreover the yellowish-green line 
 characteristic of the aurora borealis. During a jour- 
 ney in the north of Finland, in the winter of 1871- 
 1872, the same observer ^ frequently perceived 
 auroral rays below the clouds, and at a less height 
 than the summit of the mountains. Once even he 
 found himself in the midst of an aurora ; although he 
 did not see in the heavens any distinct form of an 
 aurora, the spectroscope gave in all directions the 
 characteristic greenish-yellow line, even in directions 
 where there was no snow, so that it was impossible 
 to explain these effects of light by reflection. 
 
 Hildebrandsson ' also mentions several auroras 
 seen in Sweden in the region of clouds, or even below 
 them. The second series of the ' Journal of the Inter- 
 national Polar Commission ' (1882) contains (p. 54) a 
 summary of the very interesting results obtained at 
 Ivigtut in Greenland by an engineer, Fritz. Measure- 
 ments taken simultaneously from two stations 
 (March 15, 1872) showed him that the aurora was 
 690 feet above the sea level and 1,800 feet from one of 
 the stations. On February 26 of the same year the 
 
 ' Zeitschrift der Ssterreichischen Gesellschaft filr Meteorologie, 
 vol. vi. 1871. 
 
 ^ Ibid. vol. vii. 1872. » Ibid. vol. xi. 1876. 
 
 6 
 
66 THE POIAE AUEORA. 
 
 aurora was only at a height of 180 feet, and at a dis- 
 tance of 360 feet. These auroras belonged, not to the 
 type of homogeneous arcs (third class), but to our fifth 
 class (auroras with rays). Moreover, their movements 
 appear to depend almost entirely on the configuration 
 of the land ; on the coast of Greenland they come as a 
 rule from Davis Strait, and enter the fiords or valleys, 
 up which they pass. Thus it appears that those who 
 are in the fiord often have the impression that they 
 are very near the aurora. Lastly, the movement of 
 these auroras appears to be checked when the wind is 
 strongly against them. These auroras, situated very 
 near the ground, often display the phenomena which 
 we described in Chapter II. (Auroras of the second 
 class, p. 14), 
 
 The most recent observations on polar auroras, 
 made at the time of the International Arctic Expedi- 
 tion of 1882-83, confirm the last results enumerated, 
 and have, as a rule, given fairly low figures for the 
 height of the aurora. 
 
 Measurements taken at Sodankyla, in Lapland, 
 gave for the height of the aurora numbers included 
 between 20 and 80 kilometres (12 and 18 miles), 
 recording only the observations in which the difference 
 of the angular height of the arc above the horizon in 
 the two stations, or parallax of the aurora, is more than 
 one degree — that is to say, determined with some degree 
 of certainty. In the course of these observations 
 new proofs were furnished of the uncertainty of these 
 
EXTENT, POSITION, AND FEEQXJENCY. 67 
 
 measurements. Thus out of eight observations made 
 on December 8, 1882, on the same aurora from two 
 stations connected by telephone and situated only at 
 a distance of only three miles, six gave negative 
 parallaxes ; the two observers, in spite of the short 
 distance which separated them, no longer saw the 
 same phenomenon. This is shown with even greater 
 certainty by the fact that a telephonic message to the 
 northern station, ' Measure from the red ray,' could 
 not be obeyed because at that station no trace of a 
 red ray was apparent. 
 
 During tfie same winter (1882-83) the Danish 
 expedition stationed at' Godthaab (Greenland), under 
 the direction of Paulsen, organised, to measure the 
 height of the aurora, two stations situated at a dis- 
 tance of 58 kilometres from each other (36 miles) 
 and on the same magnetic meridian. The point 
 chosen was in the vertical plane passing through both 
 stations, and the time was indicated by rockets. Out 
 of thirty- two measurements so taken, under conditions 
 for obtaining accuracy rarely realised elsewhere, only 
 ten gave a parallax of less than a degree ; in the other 
 twenty-two cases, the height of the aurora averaged 
 19 kilometres (12 miles), the lowest point of any 
 aurora being 600 metres (2,000 feet) and the highest 
 67 kilometres, 800 metres (about 42 miles). Two 
 auroras, at a height of 4,500 feet and 1,900 feet 
 respectively, hung over the gulf between the two 
 points of observation ; both were draped auroras. 
 
68 THE POLAE AUEOEA. 
 
 From all this evidence we are entitled to conclude 
 that the altitude of polar auroras varies within very 
 wide limits, and that, in spite of the opinion of cer- 
 tain authors, it is certainly possible to observe auroral 
 manifestations quite near the surface of the earth, 
 some even very complicated, such as the draped 
 auroras ; the observations of Paulsen, just mentioned, 
 leave no doubt on this head. 
 
 But let us distinguish. In mean latitudes, in 
 France and Central Europe, all measurements of the 
 height of the aurora have always given very high 
 numbers. The figures are no doubt often disputable ; 
 but, allowing for all uncertainty, it seems impossible to 
 reduce them to a few miles, as in the case of some 
 of the measurements taken in polar regions. It is 
 only in latitudes above the 55th or 60th parallel that 
 auroras are undoubtedly found at a much lower level, 
 and sometimes even quite near the surface of the 
 earth. . It seems, then, lawful to assume that the mean 
 height at which the aurora is produced diminishes as 
 we approach the poles. Perhaps exceeding 100 kilo- 
 metres (60 miles) in low latitudes, it descends to some 
 tens of miles in the Arctic regions, and may even be 
 quite near the ground. 
 
 It must be noted that the extent of the aurora 
 appears to bear a certain relation to its height. The 
 extensive auroras — those, for instance, which are 
 seen simultaneously in the two hemispheres — appear 
 to shine from an immense height. On the other 
 
EXTENT, POSITION, AND FREQUENCY. 69 
 
 hand, the auroras which are at low levels are always 
 very limited in area, or even purely local. This 
 appears to be another point in favour of the opinion 
 already stated — namely, that these two categories of 
 auroras are really distinct phenomena, both in their 
 properties and in their origin. We shall, in subse- 
 quent pages, adduce other facts in support of this 
 theory. 
 
 } 3. Frequency of the polar auroras. — Under this 
 title we comprehend only the study of the absolute 
 frequency of the aurora ; that is to say, the total 
 number of auroras observed in a given country during 
 a long period of time — one or two centuries, for 
 instance. The more or less regular variations to 
 which this frequency is subject in the same country, 
 in the course of the year or from one year to another, 
 will be treated in the next chapter. 
 
 The frequency of the aurora is determined from a 
 study of the catalogues of the aurora borealis and 
 australis, which give a list of all the auroras observed 
 in modern times, and of those of antiquity of which 
 any trace can be found in histories and chronicles. 
 Of course the data increase as we approach our own 
 day, so that the number of auroras appears to be 
 continually augmenting, But in reality there is 
 nothing to authorise such a supposition. 
 
 The first of these catalogues is that which Mairan 
 published, in 1733, in his treatise on the aurora 
 borealis. The most complete is that of Hermann 
 
70 THE POLAB AUEORA. 
 
 Fritz,' which includes the enumeration of all the 
 auroras observed between 1700 and 1872. In this 
 catalogue are summed up all those which had 
 previously appeared, notably those of Mairan, Loomis, 
 Argelander, &c. Some few others have been pub- 
 lished relating to special districts ; for instance, that 
 of Eubenson for Sweden and Mobreg for Finland. 
 Most of the following figures are borrowed from the 
 work of H. Fritz. 
 
 As the absolute frequency of the aurora is not the 
 same at all epochs, either on account of periodic 
 variation or as a consequence of insufficient observa- 
 tion in earlier times, Fritz begins by reducing all the 
 numbers proportionately to the same period — 1700- 
 1872. During these 172 years, 4,834 auroras were 
 observed in that part of Europe comprised between 
 the latitudes 46 and 55, giving an average of twenty- 
 eight auroras a year. If in a given country a certain 
 number, a, of auroras has been observed in a definite 
 time, and if during the same period we find in the cata- 
 logue a number of auroras, b, for the part of Europe 
 which we have indicated, the probable mean number 
 of auroras, n, which should have been seen in a year in 
 the country under consideration from 1700 to 1872, 
 if observations had been taken all that time, will be 
 
 N=28x- 
 
 B 
 
 ' Verzeichniss beohachteter Polarlichter, zusammengestellt von 
 H. Fritz. Gedruokt auf Kosten der K. Akademie der Wisaenschaften 
 in Wien. Vienna, 1873. 
 
EXTENT, POSITION, AND FREQUENCY. 71 
 
 It is in this way that Fritz obtained comparative 
 numbers for all countries, and, by indicating these 
 numbers on a map, the geographical distribution of 
 the frequency of the aurora. We reproduce (fig. 16) 
 the map which, according to Fritz, gives this distribu- 
 tion. The irregular ellipses traced on this map pass 
 through points where the frequency of the aurora is 
 the same. 
 
 The first line, marked 0*1, corresponds to those 
 regions where, on an average, O'l aurora is seen in a 
 year, or, in other words, one aurora in ten years. In 
 the Old World this line passes through the Straits of 
 Gibraltar, the south of Italy, Constantinople, the 
 Caspian Sea, and crosses Asia at about latitude 47°. 
 In America it cuts Mexico, and touches the souch of 
 Cuba. Within this line the frequency of the aurora 
 increases rapidly. One aurora a year is the average 
 at San Francisco, New Orleans, the north-west corner 
 of Spain, at Bordeaux, Lyons, Vienna, and Tobolsk. 
 The average at Paris is a little less than four, and a 
 little more at Berlin ; it is six in London, nine at St. 
 Petersburg, ten at Liverpool and Copenhagen. Beyond 
 this point the increase is very rapid ; the line which 
 corresponds to thirty auroras a year passes in Europe 
 through the north of Ireland, the middle of Scotland, 
 Christiania, and the White Sea ; in America, through 
 the south of Alaska, Lake Superior, Quebec, New Scot- 
 land, and the south of Newfoundland. Lastly, about 
 one hundred auroras are seen in the year at the Faroe 
 
72 THE POLAE AUEOEA. 
 
 Islands, Tronthiem, the south of Nova Zembla, the 
 northern coast of Siberia, Behring Strait, and in the 
 south of Hudson Bay and Labrador. 
 
 Fritz' map must undoubtedly be regarded only as 
 a first attempt ; in many parts the lines have been 
 drawn from observations which extend over too short 
 a period of time, or are themselves in insufficient 
 numbers, and will probably be modified by further 
 study. It seems to us, for instance, that the number 
 of auroras indicated for Newfoundland is probably far 
 too low, judging from the account of sailors who have 
 spent a long time in those seas. But these modifi- 
 cations will apply only to matters of detail, and the 
 map may be accepted as showing in its broad lines 
 the present state of our knowledge of the geographic 
 distribution of the aurora. 
 
 It will be noticed that the curves of equal frequency 
 of the aurora borealis are neither circular, nor 
 centred on the North Pole; they are rude ovals, 
 of which the centre is in about 80° north latitude and 
 75° west longitude (from Paris) — that is to say, close to 
 the western coast of Smith Strait, to the north of 
 Baffin Bay. We shall call this point, for brevity's 
 sake, the pole of the aurora. 
 
 The frequency of the aurora does not increase 
 continually as we approach the pole of the aurora ; 
 the increase in frequency, at first very rapid, as we 
 have seen, slackens and finally ceases altogether. On 
 the map, within the curve marked 100, is another, 
 
EXTENT, POSITION, AND FEEQUENCY. 73 
 
 drawn with a heavier line and lettered maximum ; 
 it passes by the North Cape, the northern extremity 
 of Nova Zembla, the North East Cape of Siberia 
 (Cape Cheliouskine), and cuts the meridian of 
 Behring Strait at latitude 70° ; then it enters America 
 a little to the west of Barrow Point, crosses 
 Hudson Bay and Labrador, and passes well to the 
 south of Greenland and Iceland. This curve unites 
 all the points where the aurora is most frequent, 
 so that the number diminishes as well within as 
 without this line as we recede from it. The whole 
 region in which the polar expeditions commonly 
 winter — Melville Island, Baffin Bay, Smith Strait, 
 &c. — are within this line and at a considerable 
 distance from it. The travellers who have sojourned 
 in these regions have all testified to the fact that the 
 auroras are far less frequent than further to the 
 south — the coasts of Labrador and Iceland, for in- 
 stance — they are also much less brilliant. This 
 diminution of the auroras in frequency and in 
 intensity has been marked by Parry, Sir John Eoss, 
 Kane, Hayes, Nares, &c. ; it is also manifest in the 
 observations collected at the meteorological stations 
 estabhshed by the Danish Government along the coast 
 of Greenland. 
 
 When, therefore, people speak of the frequency of 
 the aurora in the polar regions we must not take this 
 expression literally ; on the contrary, auroras are 
 far less numerous in the polar region proper than 
 
74 THE POLAE AURORA. 
 
 further to the south. The zone of the maximum 
 frequency descends even below latitude 60° in the 
 whole region comprised between the middle of 
 Hudson's Bay and the meridian which touches the 
 eastern coast of Greenland. 
 
 The observations of the polar aurora in the 
 southern hemisphere are too few in number, and 
 taken from stations too far removed from the Ant- 
 arctic regions, to permit us to formulate any statement 
 of the geographical distribution or of the frequency of 
 the aurora in that hemisphere. 
 
 4. Direction in which the aurora is seen. — We have 
 already briefly indicated, in describing the principal 
 forms of the aurora, that the summit of the auroras 
 in the form of an arc, or the centre of the corona, is 
 generally near the magnetic meridian ; we shall recur 
 to this matter when we come to treat of the relations 
 which exist between the aurora and terrestrial 
 magnetism. But there is another more general 
 question : to determine whether the aurora manifests 
 itself habitually in the northern or the southern 
 quarter of the horizon. 
 
 In France and throughout Central Europe the 
 aurora borealis is nearly always seen towards the 
 north, although some pass the zenith, and even dis- 
 play themselves entirely on the southern side. These 
 cases are extremely rare, yet they may occur even 
 in low latitudes. Thus on September 11, 1860, J. 
 Schmidt probably saw at Athens an aurora borealis 
 
EXTENT, POSITION, AND FEEQUENCY. 75 
 
 towards the south, which he took for an aurora 
 australis. 
 
 As we go northwards these cases of auroras seen 
 in the south become more and more frequent, in 
 Sweden and Norway for example, and we finally reach 
 a zone in which the aurora is quite as often seen in 
 the one quarter as in the other ; the position of this 
 zone of neutral direction is indicated by a dotted line 
 on the map on page 133. This zone is situated within 
 that of the maximum of the frequency of the aurora, 
 and at but little distance from it, except in the 
 neighbourhood of Iceland, where the two zones are a 
 little further apart. In all places within this zone of 
 neutral direction the aurora is far more often seen in 
 the southern quarter of the horizon. It is the case 
 in Spitzbergen, Greenland, and all Arctic countries ; 
 thus the observations of Palander in Mossel Bay 
 (Spitzbergen) give south 27° east as the mean direc- 
 tion of the summit of the arcs ; the number of the 
 auroras seen in the south is to that of the auroras 
 seen to the north as eight is to three. So in all the 
 Greenland stations the aurora is more frequently 
 seen in the south than in the north. At Upernavik, 
 for instance, out of one hundred auroras, eighty-one 
 were seen between the south-west and south-east, 
 fourteen in the east, one in the west, and four only 
 between north-west and north-east. That is, there are 
 twenty times as many auroras in the southern quarter 
 of the horizon as in the northern. It thus seems to be 
 
76 THE POLAK AUEOEA. 
 
 well established that the mean position of the aurora 
 borealis is precisely at the zenith of the points 
 situated on the line of neutral direction. 
 
 The observations collected at the time of the inter- 
 national polar expeditions in 1882-83 furnished re- 
 sults which agree at all points with those of earlier 
 date. For example, at Fort Eae, on the shores of the 
 Great Slave Lake in North-Western Canada, and at 
 Nain in Labrador, the number of northern auroras 
 was four times as great as that of southern ; these 
 two stations are therefore, as the map indicates, 
 outside the zone of neutral direction. On the other 
 hand, the number of southern auroras was twice as 
 great as that of northern at Jan Mayen Island and 
 four times as great at Kingawa Fiord (in Cumberland 
 Strait). These two points are both within the zone 
 of neutral direction, the second being the furthest 
 from it. 
 
 With these conclusions we may compare those of 
 Nordenskioeld in his work on the auroras observed 
 during the wintering of the ' Vega,' from which we have 
 already quoted (see page 62). After having com- 
 pared the auroras which he observed at the entry of 
 Behring Strait with those of other Arctic regions, 
 Nordenskioeld thinks it possible to explain the 
 principal appearances by the hypothesis of a lumi- 
 nous ring encircling the earth almost constantly in 
 the Arctic regions, the plane of this ring being 
 perpendicular to a radius of the earth passing through 
 
EXTENT, POSITION, AND FEEaUENCY. 77 
 
 its surface at lat. 80° north and long. 83° west (Paris). 
 This point is nearly that of the pole of the aurora ; 
 indeed, it may he said to he the same, when we con- 
 sider the uncertainties which govern the determination 
 of the two points. 
 
 This luminous ring or aureola would be exactly 
 above the line of neutral direction, and would have 
 a radius of about 2,000 kilometres, or 1,230 miles ; 
 its height above those points of the surface of the 
 earth which have it directly at the zenith would be 
 200 kilometres, or 124 miles. A second and larger 
 luminous ring might be in the same plane as the 
 first. 
 
 This hypothesis, which accounts satisfactorily for 
 some of the phenomena, presents certain difficulties. 
 In the first place it assigns to the neutral zone a 
 circular form, whereas on Fritz' map it is distinctly 
 ovoid ; the uncertainties which may be felt as to the 
 details of this map do not appear to be of a nature to 
 modify the curves in a sense favourable to Norden- 
 skioeld's theory ; rather the contrary seems probable. 
 Moreover, Lemstroem has pointed out that the 
 phenomena observed by Nordenskioeld are susceptible 
 of a different explanation ; the same appearance 
 would be produced by a luminous arc of 120 kilo- 
 metres wide (75 miles) and of which the height was 
 only 22 kilometres (between 7 and 8 miles). Lastly, 
 nothing seems to show that the motionless arc which 
 was the almost constant form of the aurora during 
 
78 THE POLAE AUEOEA. 
 
 the wintering of the 'Vega' is a general phenomenon, 
 nor that it would be reproduced in the same region 
 at a different time. As we shall see, the polar 
 aurora is a phenomenon which has a marked perio- 
 dicity, and it seems to be proved that the dominant 
 forms of the aurora depend, not only on topographical 
 conditions, but also in a given place on the epoch 
 of the period, on the season, and many other cir- 
 cumstances. In fact, in no other region, even situated 
 also close to the maximum zone — in Lapland, for 
 instance — has the same form been so constantly ob- 
 served as during the wintering of the ' Vega.' The 
 hypotheses of Nordenskioeld appear, therefore, to 
 require further confirmation ; it was in any case of 
 interest to compare them with the results obtained 
 by Fritz solely by the study of the comparative fre- 
 quency of the aurora and of the direction in which 
 they are observed in different countries. 
 
79 
 
 CHAPTER V. 
 
 PERIODICITY OF THE POLAB ATJEOBA. 
 
 In our study of the periodicity of the polar aurora we 
 shall consider successively : (1) the diurnal period— 
 that is to say, the variation of the mean frequency of 
 the aurora at different hours of the day; (2) the 
 annual period, or variation of the frequency of the 
 aurora according to the month and season ; (3) the so- 
 called secular period, of which the cycle may include 
 a greater or less number of years. 
 
 1. Diurnal period of the aurora. — The collec- 
 tive observations of all countries show that the 
 appearance of the aurora borealis presents un- 
 doubtedly a diurnal period — that is to say, that the 
 aurora has a manifest tendency to show itself at 
 certain hours rather than at others. This periodicity 
 exists not only for the aurora in general, but for each 
 of its forms in particular. Thus the appearance of 
 arcs, rays, discs, or patches, the hour when the rays 
 take colours, attain their maximum brilliancy, undulate, 
 and finally disappear, seem not to be a matter of 
 chance. 
 
 At Bossekop, for instance, Bravais found that the 
 
80 THE POLAR AUEOEA. 
 
 first appearance of the auroral arc took place at an 
 average hour of 7.50 p.m., that of the rays at 8.30 
 P.M., and that of the discs at 11.20 ; the appearance 
 which we have called 'palpitating' lights generally 
 only appeared towards 1.30 a.m. Lastly, the coloured 
 auroras manifested themselves especially between 10 
 and 11 P.M. ; it is also at this hour that the auroras 
 have, as a rule, their greatest intensity. It is not 
 possible, except in winter in the Arctic regions, to 
 determine the hour of the minimum of auroras, 
 since they are indistinguishable by daylight. Seven 
 or eight cases are known in which an aurora is said 
 to have been observed in the daytime ; but most of 
 these observations were taken in northern countries, 
 in winter, and at an hour when the daylight was 
 already fading ; in the other cases it is not certain 
 that the observers did not mistake for an aurora 
 certain clouds which, as we have said, offer a close 
 analogy of form with the aurora borealis. We do not 
 therefore know the law of the diurnal distribution of 
 the auroras, nor, consequently, the hour of their 
 minimum frequency. 
 
 The hour of the maximum appears, on the con- 
 trary, to be clearly determined ; it occurs, as a rule, in 
 the first half of the night, and grows later as the lati- 
 tude increases. Thus the mean hour of the maximum 
 is 8.45 P.M. at Prague ; 9.15 at Oxford ; 9.30 at 
 Upsala ; 10 at Christiania and in Canada. ; 10.30 
 at Bossekop (Lapland) ; midnight at Fort Simpson 
 
PERIODICITY OF THE POLAR AURORA. 
 
 81 
 
 and on Lake Athabasca ; 1.30 a.m. at Point Barrow 
 (Maska) ; and finally between 4 and 6 a.m. at God- 
 thaab (Greenland). In general the diurnal variation 
 . presents only a single distinct maximum ; yet the 
 observations of Palander and Wijkander gave two 
 maxima at Spitzbergen, the one at 10.30 p.m., the 
 other at 4.30 a.m., separated by a minimum at 1.30 
 in the morning. In the daytime, at 12.30, there 
 was another minimum, much more important, which 
 cannot be attributed to the daylight, as in Spitz- 
 bergen the sun remains for two months below the 
 horizon. This double variation appears to be an 
 isolated phenomenon, and is perhaps due to local 
 causes, for the Tegetthof expedition, which wintered 
 among the ice to the south of Franz Josef Land — that 
 is to say, not far from Spitzbergen — recognised only 
 one maximum at about 9 or 10 at night. The hourly 
 distribution of the auroras observed at this station is 
 as follows : 
 
 Between 10 a.m. 
 
 and 2 p.m. 
 
 
 22 auroras. 
 
 „ 2 P.M. 
 
 „ 6 P.M. 
 
 
 58 
 
 „ 6 P.M. 
 
 „ 10 P.M. 
 
 
 79 
 
 „ 10 P.M. 
 
 „ 2 A.M. 
 
 
 72 
 
 „ 2 A.M. 
 
 „ 6 A.M. 
 
 
 40 
 
 6 A.M. 
 
 „ 10 A.M. 
 
 
 28 
 
 We have seen in the preceding chapter that the 
 maximum of the absolute frequency of the aurora 
 for the different points of the globe follows an oval 
 zone which has for its centre a point situated between 
 the geographical and the magnetic poles, which we 
 7 
 
82 THE POLAE AUEOEA. 
 
 have named the pole of the aurora. Sophus Tromholt ' 
 suggested that the diurnal variations which we have 
 just indicated might be explained by a displacement or 
 oscillation of this auroral zone, this oscillation taking 
 place in the course of the twenty-four hours. In the 
 evening, towards 8 o'clock, the auroral zone would, 
 according to this hypothesis, occupy its most southern 
 position ; then it would gradually pass towards the 
 north till 8 in the morning, then moving south again, 
 to find itself in its most southern limit at 8 on the 
 following evening. The hour of the maximum for the 
 more southern districts, such as Central Europe, 
 would be that when the auroral zone was most to the 
 south — that is to say, between 8 and 9 o'clock — 
 while at the same moment it would be the hour of the 
 minimum for the regions to the north of the auroral 
 zone, such as Godthaab in Greenland, 
 
 This explanation is evidently inspired by that 
 which Weyprecht has proposed to account for the 
 annual period which we shall speak of later. But in 
 the case of the diurnal period it provokes two capital 
 objections; in all the countries which are on the 
 hypothetical course of the auroral zone, in Iceland, 
 at the North Cape, in Nova Zembla, in the south of 
 Greenland, there should be each day two maxima, at 
 the hours when the zone passes the zenith,^ either 
 when it moves towards the north or in its return 
 towards the south ; now to this day the existence of 
 
 ' Sur les piriodes de Vaurore boriale, Copenhagen, 1832. 
 
PERIODICITY OF THI) POLAR AURORA. 83 
 
 two maxima has only been observed in one place, in 
 Spitzbergen, by the Swedish expedition of 1872-73, 
 as we mentioned above. In all the other places 
 situated on the supposed course of the auroral zone 
 there is but one maximum, which is contrary to the 
 hypothesis. 
 
 The other objection is that, if the auroral zone 
 effected each day a movement of oscillation, the hour 
 of the maximum should be for all the points situated 
 on the same side of the zone and at the same distance 
 from it at absolutely the same moment, whereas the 
 diurnal variation of the aurora corresponds much 
 more nearly to the local time. Thus the maximum is 
 at 10 o'clock by the local time in Norway as in Canada 
 — that is to say, at moments which are separated from 
 each other by more than six hours of absolute time. 
 
 This tendency of the aurora to follow the local 
 time is not less evident when we consider a particular 
 aurora. Thus Donati has pointed out that the great 
 aurora of February 4, 1872, which was seen in both 
 hemispheres, had its maximum everywhere at about 
 the same local time, between 8.80 and 9.80 p.m., and 
 not at the same physical Instant, although the 
 difference in the longitude of the stations was more 
 than seven hours. 
 
 The hypothesis proposed by Tromholt cannot 
 therefore be admitted, unless with important modifi- 
 cations. If the diurnal variation of the aurora is to 
 be explained by an oscillation of the auroral zone, it 
 
84 THE POLAR AUEOEA. 
 
 cannot be by any oscillation of the zone as a whole, 
 the entire belt contracting and dilating alternately, 
 all its points approaching or receding from the pole of 
 the aurora. We must suppose not an oscillation, but 
 a progressive alteration in the form of the zone, 
 which should hollow itself, for instance, on one side 
 only, this change in form passing all round the zone in 
 the course of twenty-four hours. It is possible that 
 some such explanation may prove satisfactory. But 
 the data which we possess on the diurnal variation in 
 the frequency of auroras in the Arctic region are not 
 yet sufficiently numerous to permit of a complete 
 solution of the question. 
 
 2. Annual period of the polar aurora. — The study of 
 the annual period of the aurora presents a special 
 difficulty on account of the great variability of the 
 length of the day in mean latitudes, and especially in 
 high latitudes — that is to say, precisely in the regions 
 where the aurora is most frequent. For it is evident 
 that, other things being equal, the apparent frequency 
 of the aurora will be greater when the night is longer, 
 and conversely. Yet this difficulty is not so great as 
 it would appear at first, inasmuch as the auroras 
 generally last a considerable time, so that the end of 
 an aurora which has begun in the daytime may be 
 perceived after sunset, and especially because the 
 maximum of the diurnal frequency of the aurora is at 
 night. 
 
 Mairan was the first to discover the law of the 
 
PERIODICITY OF THE POLAR AURORA. 85 
 
 annual periodicity of the aurora borealis ; he re- 
 marked that auroras are particularly frequent in 
 France towards the months of April and October — 
 that is to say, soon after the equinoxes — and that they 
 are, on the contrary, rarer in January, and especially 
 in June. The annual period presents thus, in France, 
 two maxima and two minima. 
 
 The winter minimum occurs precisely when the 
 nights are longest — that is to say, at the epoch when 
 most auroras would be visible if they were evenly 
 distributed over the year. It must therefore be con- 
 sidered as an undoubted phenomenon, consequent on 
 the nature of the aurora. Nor can it be attributed 
 to a meteorological cause, such as a greater quantity of 
 cloud. „ For this law of periodicity is general; it is 
 manifest at all the stations of mean latitudes and in 
 both hemispheres ; now, in many countries there is not 
 more cloud in December than in March or September. 
 
 Mairan's results have been confirmed by all the 
 observations taken in mean latitudes. We will only 
 give as examples the annual variation in frequency 
 of the aurora at Paris, New York, Sweden, and at 
 Hobartstown in the southern hemisphere. In the 
 table given below the numbers for each month 
 indicate the relative frequency of the auroras in 
 hundredths — that is to say, the number of auroras 
 which, out of an annual total of 100, are seen in each 
 month. 
 
 It will be seen from this table that the quantity of 
 
86 
 
 THE POLAE AUEOEA. 
 
 cloud has no appreciable influence on the annual 
 period ; the principal maximum in Paris is in October, 
 when the aurora is twice as frequent as at the time of 
 the other maximum, in April ; yet in this last month 
 there is much less cloud in Paris than in October. 
 
 - 
 
 Paris 
 
 New Yori 
 
 Sweden 
 
 Hobartstown 
 
 January 
 
 6 
 
 7 
 
 11 
 
 3 
 
 February 
 
 
 
 8 
 
 7 
 
 12 
 
 5 
 
 March 
 
 
 
 8 
 
 9 
 
 13 
 
 8 
 
 April . 
 
 
 
 9 
 
 11 
 
 7 
 
 24 
 
 May . 
 
 
 
 8- 
 
 7 
 
 1-5 
 
 5 
 
 June . 
 
 
 
 2 
 
 7 
 
 
 
 3 
 
 July 
 
 
 
 5 
 
 9 
 
 0-5 
 
 5 
 
 August 
 
 
 
 8 
 
 11 
 
 5 
 
 
 
 September 
 
 
 
 14 
 
 10 
 
 13 
 
 13 
 
 October 
 
 
 
 18 
 
 10 
 
 15 
 
 21 
 
 November 
 
 
 
 8 
 
 6 
 
 11 
 
 3 
 
 December 
 
 
 
 6 
 
 5 
 
 11 
 
 10 
 
 The numbers, in the case of Hobartstown, result 
 from a less number of years of observation than for 
 the other stations. They clearly show the two maxima 
 of autumn and spring, but it would not be safe to 
 draw any other conclusions from them. 
 
 In the three series of the northern hemisphere the 
 two maxima of spring and autumn are very distinct ; 
 it will also be remarked that the principal maximum 
 is that of the autumn. This seems to be a general 
 law, due probably to the influence of meteorological 
 conditions on the production of auroras. 
 
 The two minima of winter . and summer appear 
 also to be unequal ; but this inequality is due, in part 
 if not entirely, to the difference of the length of the 
 
PEEIODICITY OF THE POLAP AUEOEA. 87 
 
 nights in the two seasons. Thus the frequency of the 
 auroras, nil in the month of June in Sweden, where 
 there is properly speaking no night, is already sensible 
 in Paris and still greater in New York, where the 
 summer nights are longer than in Paris. Under 
 these conditions it is hard to say whether the two 
 minima are really unequal ; it is even possible that 
 the principal minimum is the winter one. The New 
 York series — which is particularly interesting from this 
 point of view, since it seems to indicate that the 
 principal minimum falls in December — comprehends 
 unfortunately a less number of observations than the 
 others, so that it cannot be regarded as giving definite 
 results. Local climatic conditions may also play a 
 part in the relative importance of these two minima ; 
 but the existence of two annual minima in mean lati- 
 tudes is indisputable. 
 
 This law of annual periodicity appears to be 
 modified in higher latitudes. The autumn maximum 
 grows later and later, and that of spring earlier, both 
 thus approaching the winter solstice. This fact, 
 noted first by Levering, has since been verified by 
 numerous observers. It even happens, in sufficiently 
 high latitudes, that the two maxima are fused in one, 
 which falls near the winter solstice. We give in the 
 following table the proportion of auroras observed 
 each month in polar regions, the annual total of 
 auroras being supposed to be 100. The first column 
 results from a comparison of the observations collected 
 
88 
 
 THE POLAR AUEORA. 
 
 to the north of Baffin Bay by the polar expeditions 
 of Parry, McClintock, Kane, Hayes, and Bessels ; we 
 head them ' polar expeditions.' The second is deduced 
 from the observations pursued uninterruptedly by 
 Kleinschmidt at Godthaab in Greenland from 1865 to 
 1882. This series is the most important of all which 
 are available for these regions, both because of the 
 care bestowed on the records and because of the 
 length of time during which they were prosecuted, 
 and especially because, being entirely due to one 
 person, they are susceptible of strict comparison 
 throughout. We give no number for the four months 
 of May, June, July, and August, since the absence of 
 night during that time permits of no observations of 
 the aurora borealis. 
 
 Polar expeditions 
 
 Godthaab 
 
 September 
 
 1 
 
 . 8 
 
 October . . 
 
 6 
 
 • 14 
 
 November 
 
 13 
 
 i 16 
 
 December . 
 
 20 
 
 . 18 
 
 January . 
 
 24 
 
 . 17 
 
 February , 
 
 23 
 
 . 14 
 
 March 
 
 10 
 
 . 10 
 
 April 
 
 
 
 3 
 
 The Godthaab series is much the best, for the 
 reasons above mentioned, but it will be seen that 
 both are agreed in giving but one maximum ; it is in 
 December for Godthaab, in January for the polar 
 expeditions which wintered in the same region, but 
 yet further to the north. 
 
 Weyprecht proposes to explain the annual varia- 
 
PERIODICITY OP TEE POLAR AURORA. 89 
 
 tions in mean and polar latitudes by a periodic oscil- 
 lation of the zone of the maximum frequency of the 
 aurora. According to this theory, the zone descends 
 towards the south and recedes northwards again 
 twice a year, occupying its most southern position at 
 the equinoxes and its most northern at the solstices. 
 This hypothesis accounts for the two annual maxima 
 and minima of mean latitudes, and also for the 
 winter maximum of high latitudes. It also points to 
 a second maximum in the latter at the summer 
 solstice ; but the complete absence of night at that 
 season prevents the verification of this second conse- 
 quence of Weyprecht's hypothesis. 
 
 This hypothesis has been adopted by many 
 authorities, among others by Tromholt, who even 
 wished, as we have said, to extend it so as to 
 explain the diurnal periodic variation. But latterly 
 it has found an opponent in Paulsen, Director of the 
 Meteorological Institute of Copenhagen. He points 
 out ' that the two maxima of the equinoxes and the 
 winter minimum are observed at St. Petersburg, 
 Abo, Stockholm, and Christiania, whereas at Hammer- 
 fest, in the north of Norway, there is but one maxi- 
 mum, at the winter solstice. This latter station 
 should therefore, according to the hypothesis, lie at 
 all seasons to the north of the zone of the maximum 
 frequency of the aurora, and this is contrary to 
 
 ' ' Contribution k notre Connalssance de I'Aurore borSale ' {Bulletin 
 de I'Acadiinie royale danoise des Sciences et des Lettres, 1889). 
 
so THE POLAE AXJEOEA. 
 
 known fact. Paulsen remarks, in addition, that to 
 explain the difference in the annual variation of mean 
 and high latitudes there is no need to suppose a dis- 
 placement of the zone of maximum frequency. It is 
 enough to assume that a more active production of the 
 phenomena of the aurora borealis in mean latitudes 
 involves thereby a slackening of activity in the zone 
 proper to the aurora. This hypothesis is an extremely 
 probable explanation of the facts ; it agrees completely, 
 as we shall see later, with the theory of Edlund. This 
 theory explains the aurora by a flow of electricity 
 from the equator towards the poles ; now, it is clear 
 that if a greater part of this flow is manifest at a 
 given moment in mean latitudes there will be less 
 for the polar regions. Finally, direct observation 
 seems to justify this view ; Kleinschmidt has shown 
 that auroras were either non-existent or very faint at 
 Godthaab at seasons when great auroras were seen in 
 low latitudes. 
 
 Thus, to sum up the argument, if in high lati- 
 tudes more auroras are seen in winter than at other 
 seasons, this is due merely to the fact that there are 
 at that time fewer manifestations of the aurora in 
 mean latitudes than at the equinoxes. The zone of 
 the maximum frequency of the aurora remains at the 
 same invariable position, or nearly so ; only auroras 
 are a little less numerous in this zone when they are 
 more numerous in lower latitudes. It only remains 
 to explain why the annual period of the aurora 
 
PERIODICITY OF THE POLAE AUEOEA. 91 
 
 presents two maxima, at the equinoxes, in mean 
 latitudes. 
 
 3. Secular period of the aurora borealis: rela- 
 tion of the aurora with the spots on the sun. — 
 The study of the period of the aurora, embracing 
 several years, presents great difiSculties on account ot 
 the lack of regular observations which may be com- 
 pared together and extending over a sufficient space 
 of time. Every time that, in a given country, there is 
 a change of observer, we remark a sudden variation 
 in the annual number of auroras. It is necessary, 
 therefore, as far as possible to collect the observations 
 over a whole region, and not content ourselves with a 
 single station, for it often happens that in two neigh- 
 bouring places an aurora will be noted in the one 
 which is unperceived at the other by a less attentive 
 observer. At the present day, with the multiplication 
 of observatories, it is hardly possible for an aurora to 
 escape notice, unless the state of the weather is 
 absolutely unfavourable. Eecent catalogues are then 
 complete, or nearly so ; but this is not the case with 
 regard to those of a century or two back. We have 
 to search for the chance mention of auroras in the 
 pages of historians ; and even so we only attain to 
 very incomplete lists, which include only auroras of 
 exceptional intensity. At still earlier dates the de- 
 scriptions of chroniclers are couched in such ambiguous 
 terms that it is often impossible to tell whether they 
 relate to an aurora, a meteor, or a comet. In spite of 
 
92 THE POLAE AUEOEA. 
 
 these difficulties, it has been established that the ap- 
 }>earances of the aurora borealis are periodic, and these 
 longer periods are the more interesting that they, seem 
 to coincide with those recognised in the case of other 
 phenomena, such as terrestrial magnetism and the 
 spots on the sun. The question of the secular variations 
 of the aurora demands, therefore, a detailed study. 
 
 The idea of periodicity in the returns of the aurora 
 borealis occurred to Mairan. Although he had not 
 determined the length of the period, he mentions all 
 the occasions of the renewal of the aurora — that is to 
 say, of the maxima of frequency — of which he could 
 find the trace as far back as classic times, by con- 
 sulting historians and chroniclers. He even goes 
 further and asks whether it would not be possible to 
 establish some analogy between the frequency, the 
 cesHation, and the return of the spots on the sun and 
 the manifestations of the aurora borealis.' ' This 
 idea is encouraged,' he adds, ' by the fact that during 
 these last five or six years, when the aurora borealis 
 has been so frequent, so also have been the spots on 
 the sun. It is known that at the beginning of the 
 last century, after the invent! m of the telescope, the 
 sun was hardly ever seen without spots ; and there 
 were at times such numbers of them that P. Scheiner 
 said that he once counted as many as fifty. They 
 afterwards became more rare, so that from the middle 
 of the century until 1670 — that is to say, for twenty 
 
 ' Mairan, TraiU de I'Aurore boriale, 1st edition, 1733, p. 250. 
 
PERIODICITY OF THE POLAK AURORA. 93 
 
 years — only one or two were seen, and these only for a 
 short time. Now, as we have seen, there was a great 
 number of auroras at the beginning of the seventeenth 
 century and till after 1621, after which date we hear no 
 more of them till 1686.' 
 
 After Mairan many authors have discussed this 
 question, and proposed to explain the returns of the 
 aurora by different periods. Hansteen believed that 
 the period was ninety-five years on an average ; 
 Denison Olmsted gives a period of sixty-five years 
 divided into two parts, the one of twenty-five years, 
 during which the auroras are numerous, the other of 
 forty years, during which the cause which produces 
 the auroras is in repose. But none of these tentatives 
 have led to any satisfactory results until there was a 
 return to Mairan' s idea of a relation between the spots 
 on the sun and the aurora borealis. 
 
 It is known that the periodicity of the sun spots, 
 divined by Fabricius in 1610, was definitely proved 
 by Schwabe in 1826, whose studies were ampUfied 
 and confirmed by a great number of observers and 
 men of science, among whom we may mention Warren 
 de la Eue, Carrington, Secchi, Spoerer, and especially 
 Eudolf Wolf, of Zurich. According to the latter, the 
 spots on the sun observe a period of a little more than 
 eleven years (eleven years and two months exactly) 
 composed of two unequal parts ; there are, on an 
 average, six years between the maximum and the 
 minimum which succeeds it, and five years between 
 
94 THE POLAR AUEOEA. 
 
 the latter and the next maximum. The period of 
 increase is thus shorter than the period of decrease. 
 
 These facts relating to the sun spots are perfectly 
 certain at the present day. The periods are not all 
 precisely equal, being sometimes a little longer or 
 shorter ; but they never fail to manifest themselves, 
 and there is always an enormous difference between 
 the number of spots which corresponds to a year of 
 maximum and that of a year of minimum. 
 
 In the following table we give, from the researches 
 of E. Wolf and from a summary of these which has 
 been recently published by M. A. Wolfer,' the epochs 
 of the maxima and minima of the spots on the sun 
 since 1610. We add to these after 1700 the relative 
 numbers of the sun spots during the year under 
 consideration. These numbers are obtained according 
 to the method suggested by E. Wolf, by counting 
 simply the number of isolated spots, and adding them 
 together ; adding to these the sum of the numbers of 
 groups of spots, each group being reckoned as equiva- 
 lent to ten spots. We indicate only in round numbers 
 the years of maxima and minima, neglecting fractions 
 of a year. These are, indeed, still uncertain to the 
 extent of a few months ; in earlier centuries the 
 uncertainty may amount to a year or two. 
 
 The periodicity of the solar spots which is set forth 
 in the above table is a most marked phenomenon : 
 
 ' Bihliothique universelle de Oenive. ' Archives dea Sciences 
 physiques et naturelles,' vol. xxvi. 1891, N". 12. 
 
PEEIODICITY OP THE POLAR AUEOEA. 
 
 95 
 
 Epochs of the maxima and minima of the spots on the sun. 
 
 
 Belative number of 
 
 the spots, after 1700. 
 
 
 Miuima 
 
 Maxima 
 
 Eelative 
 numbers 
 
 Minima 
 
 Maxima 
 
 Relative 
 numbers 
 
 1610 
 
 
 
 
 1761 
 
 86 
 
 
 1615 
 
 — 
 
 1766 
 
 
 11 
 
 1619 
 
 
 
 
 
 1769 
 
 106 
 
 
 1626 
 
 — 
 
 1775 
 
 
 7 
 
 1634 
 
 
 — 
 
 
 1778 
 
 154 
 
 
 1639 
 
 — 
 
 1784 
 
 
 10 
 
 1645 
 
 
 — 
 
 
 1787 
 
 132 
 
 
 1649 
 
 — 
 
 1798 
 
 
 4 
 
 1655 
 
 
 — 
 
 
 1804 
 
 73 
 
 
 1660 
 
 — 
 
 1810 
 
 
 
 
 1666 
 
 
 — 
 
 
 1816 
 
 46 
 
 
 1675 
 
 — 
 
 1823 
 
 
 2 
 
 1679 
 
 
 — 
 
 
 1830 
 
 71 
 
 
 1685 
 
 — 
 
 1833 
 
 
 8 
 
 1689 
 
 
 — 
 
 
 1837 
 
 138 
 
 
 1698 
 
 
 
 1843 
 
 
 11 
 
 1698 
 
 
 — 
 
 
 1848 
 
 124 
 
 
 1705 
 
 49 
 
 1856 
 
 
 4 
 
 1712 
 
 
 
 
 
 1860 
 
 96 
 
 
 1718 
 
 51 
 
 1867 
 
 
 7 
 
 1723 
 
 
 10 
 
 
 1870 
 
 139 
 
 
 1727 
 
 90 
 
 1878 
 
 
 3 
 
 1733 
 
 
 5 
 
 
 1883 
 
 04 
 
 
 1730 
 
 83 
 
 1889 
 
 
 6 
 
 1744 
 
 1750 
 
 5 
 
 83 
 
 
 
 
 1755 
 
 
 10 
 
 
 
 
 the relative number of spots is only six on an average 
 at the time of the minima ; it is ninety-three (or 
 fifteen times as many) at the time of the maxima. 
 
 In 1852 Sabine, Wolf, and Gauthier announced 
 almost simultaneously that the variations of magnetic 
 declension were also subject to regular periodicity, 
 and that their period corresponded exactly with that 
 of the sun spots. This coincidence, which is now 
 perfectly recognised, became the point of departure 
 
96 THE POLAE AURORA. 
 
 for a series of analogous researches, and soon men 
 sought to estabhsh relations between the spots on the 
 sun and all meteorological phenomena. This was 
 carrying things too far, and relations which were 
 wholly illusory were the result ; nevertheless, some 
 curious and genuine results were attained, among 
 which may be reckoned those which concern the 
 aurora borealis. Suggested, after Mairan, by Steven- 
 son, J. A. Brown, E. Wolf, Secchi, and Hansteen, the 
 relation between the aurora borealis and the sun spots 
 was studied and finally proved by Fritz, Loomis, and 
 Lovering. Fritz appears to have been the first who 
 distinctly laid down the law that the number and 
 importance of the auroras follow exactly the same 
 variation as the spots on the sun, so that the epochs 
 of the maxima and minima coincide almost exactly 
 for the two orders of phenomena. 
 
 Among the epochs of the maxima of the aurorji 
 borealis we may mention in especial the years 1615, 
 1686-87, 1707, and 1728, which are indicated by 
 Mairan, and correspond fairly exactly with the maxima 
 of the sun spots, as may be seen from the preceding 
 table. In our own century the same coincidence is 
 nhown principally in the years 1804, 1810, 1830, 1848, 
 and finally in the winters of 1859-60 and 1870-71, 
 in which we have more than once mentioned numerous 
 and exceptionally extensive auroras. 
 
 Yet if the agreement appears to be sufficiently 
 satisfactory as a general rule, it must not be denied 
 
PEEIODICITY OF THE POLAE AUEOEA.. 
 
 97 
 
 that there are considerable discrepancies in detail, 
 as will be seen from the diagram (fig. 17), which 
 represents by the lower curve the variation of the 
 sun spots (relative numbers) from 1720 to 1875, and, 
 for the same period, by the upper curve, the number 
 of auroras seen each year in Central Europe, between 
 the latitudes 46° and 55°, according to Fritz's catalogue. 
 
 ' tTii' IX: 
 
 -17.EQ- 'za 
 
 
 .,1 
 
 FiQ. 17. — Comparison op the Pbbqtjbnct op the Aueoka with 
 THE Spots on the Sun. 
 
 The line of the frequency of the aurora is far less 
 regular than the other ; it is wanting in continuity, 
 and presents atrupt transitions. Certain maxima of 
 sun spots do not correspond to a maximum of auroras, 
 for instance, in 1761 ; conversely, as in 1732, 1733, 
 and 1734, there is a maximum of auroras where there 
 is a minimum of sun spots. Finally, the epochs of 
 
98 THE POLAK AUKOEA. 
 
 the maxima and of the minima of the auroras outrun 
 or lag behind, in an irregular manner, the corre- 
 sponding epochs of the period of the sun spots. 
 
 These discrepancies may be partly due to the fact 
 that the auroras have not been sufficiently observed. 
 In order to be sure that none escape observation . 
 regular watch should be kept in countries situated in 
 longitudes sufficiently far apart, so that it should 
 always be night in one or other : for instances, in 
 Central Europe, in the United States, and in the north 
 of China. It would also be desirable to have similar 
 stations in high latitudes ; but these observations 
 should be considered separately from those of mean 
 latitudes. 
 
 For, according to the researches of Tromholt, 
 based on the observations of the aurora borealis 
 collected in Greenland, it would seem that in that 
 country the relation which we have indicated as 
 existing between the aurora and the spots on the sun 
 is reversed : the maximum of auroras being manifest 
 during the minimum of sun spots, and inversely, that 
 is to say exactly the opposite of what is observed in 
 mean latitudes. Tromholt explains this contrast 
 between Greenland and mean latitudes as he had 
 already explained the diurnal period,* by supposing 
 that the auroral zone executes, during the period of 
 the sun spots — i.e. in a little more than eleven 
 years — a movement of oscillation from the north 
 to the south and conversely. We have already set 
 
PEEIODICITY OF THE POLAR AURORA. 99 
 
 forth, in our study of the annual variation of the 
 aurora, the objections which may be made to this 
 theory of an oscillation of the auroral zone, and we 
 have indicated a simpler and more natural explana- 
 tion, proposed by Paulsen. This explanation accounts 
 perfectly for the antagonism apparent between the two 
 regions, whether in the annual variation or any other 
 period. However this may be, this difference may 
 certainly be invoked as one of the causes which tend 
 to disturb the parallelism between the period of the 
 aurora and the spots on the sun. For if the maximum 
 of the auroras corresponds, in mean latitudes, to the 
 maximum of the solar spots and to the minimum 
 in the arctic regions, it is clear that there must be 
 between these two an intermediary zone, in which the 
 law of periodicity is undetermined, and may be 
 inappreciable or even quite different. Now this zone 
 is precisely that in which auroras are most frequent; 
 if then we consider together and without distinction 
 the auroras of the opposing regions, or even those only 
 of the intermediate zone, it will be easily understood 
 that the law of periodicity is no longer very obvious. 
 
 Another disturbing cause, on which we have 
 already more than once insisted, is that we include 
 under the common designation of aurora borealis 
 phenomena which appear to be distinct both ia their 
 producing cause and in their form and extent. If a 
 first class of auroras, peculiar to high latitudes, is of 
 purely terrestrial and even local origin, while another 
 
100 THE POLAE AUEOEA. 
 
 class depends more particularly on the yet unknown 
 cause -which produces also the variations in the spots 
 on the sun, it becomes quite natural that the relation 
 of the sun spots with this second class of auroras 
 should be obscured in part by the confusion between 
 the two sorts of aurora. It is, therefore, desirable to 
 reckon apart henceforward the auroras which are pro- 
 duced over a wide extent of country and which are 
 accompanied by general magnetic disturbances, and 
 those which, on the contrary, have rather a local 
 character, and coincide with no abnormal movements 
 of the magnetic needle in mean latitudes. It seems 
 to us probable that the general auroras of the second 
 class, considered alone, would show a periodic varia- 
 tion much more closely in agreement with that of 
 the spots on the sun than has hitherto been 
 established. 
 
 We have considered at some length the period of 
 eleven years shown by the aurora borealis. It is in 
 truth the most obvious and the one which is most 
 easily recognised. But there are besides other periods, 
 both longer and shorter. Wolf discovered in the 
 alternatives of the sun spots a period of about fifty-five 
 years and a half, comprehending nearly five of the 
 periods of eleven years. The superposition of these 
 two periods results in the accentuation and weakening 
 alternatively of certain maxima and minima of the 
 undecimal period. Thus the maxima of the sun spots 
 were particularly marked in 1778 and 1787, and in 
 
PEEIODICITY OF THE POLAE AUEOEA. 101 
 
 1837 and 1848, while the intermediate maxima, and 
 especially that of 1816, were relatively weak. 
 
 An analogous period is manifest also in the 
 auroras. The most important maxima which have 
 been noted in Europe are those of 1788 and 1848, 
 which correspond nearly to the period under con- 
 sideration, and coincide with the great maxima of 
 the spots on the sun. Lastly, as in the case of the 
 spots on the sun, the maximum of 1817 was very 
 weak. 
 
 Beside these coincidences we must set cases of 
 marked divergence. Thus the maximum of 1870, 
 which was remarkable both for its auroras as for the 
 sun spots, does not appear to enter into the period we 
 are considering. The duration of this period, esti- 
 mated at fifty -five and a half years, cannot, however, 
 be considered as exactly known ; the interval of time 
 covered by the observations is not yet long enough to 
 furnish sufficient elements for calculation. 
 
 Besides these long periods, other and much shorter 
 ones have been noted ; it would seem easy to deter- 
 mine these with great exactitude ; but the amount of 
 the variation corresponding to these shorter periods is 
 much slighter, and this renders the periods less dis- 
 tinct. It is known that the sun spots are subject to 
 a period of a little more than twenty-seven days, 
 corresponding to the apparent rotation of the sun, or 
 at least to that of the spots. It would seem that there 
 exists in t\e frequency of the auroras an identical or 
 
102 
 
 THE POLAE AUEOEA. 
 
 very similar period. In any case great auroras are 
 frequently seen at intervals of .28 or 30 days ; we give 
 some examples of these coincidences : 
 
 October 17, November 17, 1818. Interval 31 daya. 
 
 January 19, February 19, 1852. „ 31 
 
 September 1, October 1, 1859. „ 30 
 
 October 14, November 19, 1865. „ 31 
 
 October 22, November 14, 1868. „ 28 
 
 April 15, May 14, 1869. „ 29 
 
 January 3, February 1, 1870. „ 29 
 
 September 21, October 34, 1870. „ 30 
 
 An analysis of the epochs of the recurrence of 
 auroras between September 22, 1846, and February 4, 
 1872, gives Fritz a period of 27 days, 7 hrs., equivalent 
 consequently to that of the spots on the sun. Veeder,' 
 studying the records of observations taken in the 
 United States, finds a period of twenty-seven and a 
 quarter days. He thinks, moreover, that he may ven- 
 ture to assert that every time that an aurora is seen 
 there is a group of spots on the eastern border of the 
 sun. According to him there is no exception to this 
 rule, and auroras are only to be seen when such 
 groups of spots are on the eastern border of the sun 
 to the exclusion of every other position. The con- 
 verse does not hold ; though auroras always coincide 
 with the appearance of spots on the eastern border of 
 the sun, sun spots may exist in that position without 
 any corresponding manifestation of auroras ; but, in 
 the latter case, the place of the aurora would be taken 
 
 ' Proceedings of the Rochester Academy of Science, vol. ii., 
 Rochester, 1893, and American Meteorological Journal, vol. ix., 
 p. 105, June 1803. 
 
PERIODICITY OF THE POLAE AUEOEA. 103 
 
 by storms. This substitution of storms for auroras, if 
 established, would be a very remarkable fact, and of the 
 greatest importance to the theory of the phenomenon. 
 On the other hand, some observers think that' the 
 aurora borealis and magnetic disturbances coincide 
 with the passage of the spots over the central 
 meridian of the sun, and not with their appearance 
 on its eastern edge. There is, moreover, a distinction 
 to be established between the quiet spots and those 
 which present an appearance of violent eruption, 
 easily recognised by the spectroscope ; the latter 
 only are in relation with the aurora borealis. It is 
 to be desired that further researches, carried on in 
 different countries, should be brought to bear on the 
 laws enunciated by Veeder. 
 
 To conclude : it results from all that precedes 
 that the aurora borealis, in spite of its apparent 
 irregularity, observes well-established periods — for 
 instance, the diurnal period, the annual period, and 
 the period of a little more than eleven years. Among 
 the periods of which the duration is less exactly 
 known, but of which the existence seems to be 
 proved, there is one of about twenty-eight days and 
 another of about fifty-five and a half years. Others 
 have been surmised, especially one of 220 years, but 
 they are extremely doubtful, and we will not stay to 
 consider them. 
 
104 THE POLAB AUKOKA. 
 
 CHAPTEE VI. 
 
 OF THE AUROEA EELATIONS WITH MBTEOEOLOGICAL 
 PHENOMENA. 
 
 1. Relation of the aurora with the weather. — Some 
 link has been sought for a long time between the 
 polar aurora and various meteorological conditions, 
 the height of the barometer, rainfall, wind, &c. ; but 
 hitherto only negative or contradictory results have 
 been arrived at. Whereas in Labrador, for instance, 
 coloured auroras foretold fine weather, in Greenland, 
 at no great distance, they seemed to herald the south 
 wind and storms ; this was in particular the opinion 
 of Scoresby. Hansteen concluded from his long 
 series of observations, that at Christiania the aurora 
 borealis was nearly always followed by a lowering of 
 the temperature ; but on the other hand, Argelander 
 says that at Abo and at Helsingfors the barometer fell 
 and the temperature rose during the auroras. In short, 
 it would not be difficult to give many similar pairs 
 of contrasting opinions on the relations which may 
 exist between the aurora borealis and the weather, 
 even in neighbouring districts. And most authorities 
 now admit that there is no connection between the 
 
EELATIONS WITH METEOROLOGICAL PHENOMENA. 105 
 
 aurora and the different aspects of the weather, and 
 that the two orders of phenomena are entirely inde- 
 pendent. 
 
 Yet this independence is perhaps more apparent 
 than real, and these contradictory conclusions are 
 perhaps due to the fact that the problem is badly 
 stated. First of all, it is evident that there is no 
 possible relation between the weather and the great 
 auroras which are seen at one and the fame time over 
 nearly the whole surface of the earth ; we must begin 
 then by eliminating all these great auroras, and con- 
 sider only the local auroras, which are especially 
 frequent in high latitudes. It is necessary to remark, 
 further, that so long as meteorological science was 
 content to study isolated phenomena, in each locality 
 separately, apparently contradictory results were also 
 attained : in one country, the south wind caused a 
 fall in the barometer ; in another, though at but little 
 distance, it was the north or west wind that produced 
 this effect, and so on. In order to draw any conclu- 
 sion from facts which were in such apparent contra- 
 diction, it was necessary to consider not only what 
 happens at a given point, but the simultaneous varia- 
 tions of the various meteorological elements and their 
 distribution over a wide extent of country. For 
 instance, the connection between the movements of 
 the barometer and the direction of the wind only 
 became intelligible when charts, showing the distri- 
 bution of pressure and the direction of the wind 
 
106 THE POLAE AUEOEA. 
 
 at a given moment over the whole of Europe, were 
 obtainable. 
 
 If there be any relation between the manifesta- 
 tions of a certain class of auroras (we have said above 
 that there can be no such relation in the case of the 
 great auroras) and any meteorological phenomena, 
 this relation will certainly be discovered by analogous 
 means, by studying the general distribution of pres- 
 sure, of the temperature, of humidity, and of the 
 winds over a great part of the northern hemisphere, 
 at the time of the production of the aurora. The only 
 attempt which has hitherto been made in this 
 direction is that of Forsman, who arrived at the 
 following conclusions : 
 
 The variations in the barometer are generally 
 opposed in the two parts of Europe which are 
 separated by a line passing from the north of 
 Scotland to the Black Sea. Now when auroras are 
 observed in Sweden the barometer rises, that is, there 
 is already a maximum of pressure in that part of 
 Europe situated to the north-east of the above 
 mentioned line ; the barometer falls on the other 
 hand, i.e. there is a minimum of pressure, in the 
 south-western part. These results need to be con- 
 firmed and extended by further research ; they serve 
 at any rate to show the direction which study should 
 take. 
 
 In the Arctic seas, which are alternately frozen in 
 winter and free in summer, the aurora seems to 
 
EELATIONS WITH METEOEOLOGICAL PHENOMENA. 107 
 
 follow the limit of the ice. This fact, to which 
 Bravais first drew attention in Lapland, has since 
 been confirmed by Weyprecht in Franz Josef Land, 
 by the various Swedish expeditions to Spitzbergen, 
 and more recently, in 1882-83, by the Austrian Polar 
 expedition to Jan Mayen Island. This is an evident 
 proof that the production of the aurora borealis 
 may be influenced by certam meteorological condi- 
 tions 
 
 Independently of the relations which may exist 
 between the appearance of the aurora and the 
 particular state of the atmosphere, there are certainly 
 other relations between this state and the form under 
 which the aurora manifests itself ; it would seem that 
 certain forms of the aurora are more commonly seen 
 in particular countries, and are consequently in relation 
 with the climatic and topographical conditions of the 
 locality. The laws of the geographical distribution 
 of the different forms of auroras need therefore 
 special study, and it is probable that the results of 
 such study would have an important bearing on the 
 theory of the phenomenon. There are at present few 
 data on this head. " 
 
 In the north of Behring Strait, where the ' Vega ' 
 wintered, the aurora constantly presented the form of 
 an homogeneous arc, while the radiated forms were 
 extremely rare ; during the whole winter only one 
 aurora in the form of drapery was seen. Is this 
 predominance of the auroras of the third type a 
 
108 THE POLAR AURORA. 
 
 geographical fact, or does it depend solely on the 
 particular characteristics of the winter of 1878-79 ? 
 This question can only be solved by further observa- 
 tions taken at another epoch in the same region, and 
 if possible at another phase of the undecimal period, 
 for it is also possible that the general form of the 
 aurora is not the same at the moments of the maxima 
 and minima. 
 
 We have somewhat more precise data on the 
 draped auroras. With very rare exceptions, notably 
 an aurora in the form of drapery seen in Paris on the 
 night of April 15-16, 1869,' this form of aurora has 
 been observed only in districts near the seas which 
 in winter remain open and free from ice. The 
 countries where these auroras have been chiefly seen 
 are the north of Norway, Nova Zembla, Franz Josef 
 Land, Spitzbergen, the eastern coast of Greenland, 
 and Newfoundland. It may be noticed that these 
 countries are all in the neighbourhood of the baro- 
 metric minimum, which obtains as a rule in winter in 
 the North Atlantic. This coincidence merits atten- 
 tion. 
 
 2. Relation of the aurora with the clouds. — Clouds 
 constitute the meteorological phenomenon which 
 offers the clearest and least disputable relation with 
 the aurora borealis. We have already mentioned 
 (page 15) the close resemblance which obtains 
 
 • We reproduce, (fig. 18) the appearance of this aurora, from the 
 drawing of Silbermann. 
 
RELATIONS "WITH METEOROLOGICAL PHENOMENA. 109 
 
 between certain forms of the aurora and the clouds 
 •which are known as cirro-stratus and cirro-cumulus, 
 a resemblance so close that it is often difficult to 
 judge whether a given effect is due to real auroral 
 lights, or to clouds lit up by some reflected Hght. 
 We also remind our readers that we have mentioned 
 several cases in which a halo produced by the refrac- 
 tion of the light of the moon through the ice needles 
 which constitute the cirrus, has been observed at the 
 same time as an aurora. 
 
 Sometimes these clouds are stretched out in long 
 parallel lines, which, by the effect of perspective, seem 
 to converge upon two opposite points of the sky. 
 These bands of cirrus are, as a rule, in one or other 
 of two directions. Sometimes they are sensibly 
 parallel to the needle of the compass, and lie conse- 
 quently north and south, within a degree or two ; 
 they are then known as polar bands. At other times, 
 on the contrary, they take a direction perpendicular 
 to the preceding. In the first case they are oriented 
 like the isolated rays of the aurora ; in the second 
 they recaU the form and the disposition of the arcs. 
 
 At Bossekop the French Commission had occasion 
 to observe especially the cirrus clouds directed per- 
 pendicularly to the magnetic meridian, that is to say, 
 in the direction of the auroral arcs. The mean 
 orientation of these bands of cloud, deduced from 
 twenty- four distinct observations, was E. 28° N. — W. 
 28° S., while the mean orientation of the arcs of the 
 
110 THE POLAE AtTEOEA. 
 
 aurora was E. 21° N. — W. 21° S. The difference is only 
 seven degrees, which is very httle, especially when we 
 consider the difiSculty of such measurements and 
 the irregularities which are not uncommon in phe- 
 nomena of this nature. It is therefore legitimate to 
 assume with Bravais that the cause, whatever it may 
 be which determines the orientation of these bands of 
 cloud, is also that which reg\ilates the position of the 
 auroral arcs. 
 
 Not only have these bands of cloud a close analogy 
 in form and position with certain polar auroras, but 
 as we have already indicated there seems often to be 
 the closest connection between the two phenomena. 
 Sometimes, when the aurora borealis disappears in 
 the morning before the light of day, its place is taken 
 in the sky by bands of cirrus ; more often still, these 
 clouds are first seen in the daytime, and the following 
 night the rays, or the arc, of the aurora replace them. 
 
 Since Frobesius, who was the first to indicate 
 some of these relations in 1739, a great number of 
 observers have given numerous and curious examples 
 of the analogies of the aurora with clouds. Hell, in 
 1769, notices that these bands of cloud are, like the 
 aurora, much more common in the arctic regions 
 than in mean latitudes; he also signalised the 
 apparent transformation of the aurora of the night 
 into the cloudy band of the day, and vice versa. 
 Weber and H. Fritz also remarked that every time 
 that they observed polar bands of cloud during 
 
RELATIONS WITH METEOROLOGICAL PHENOMENA. Ill 
 
 the day there was an aurora the following night. 
 Winnecke considered the analogy so complete that he 
 does not hesitate to regard these clouds as the vehicle 
 of the auroral lights. 
 
 After prolonged study of the subject Weyprecht 
 arrives at the same conclusion. In his opinion the 
 luminous phenomena of the aurora are such that the 
 light seems to be intimately connected with material 
 particles. Wherever two or more rays cross, the 
 intensity of the light augments ; and this is also the 
 case where an auroral band seems to make a fold ; 
 moreover, the wind seems to act upon the aurora, 
 which appears torn after a tempest; finally, the 
 presence of clouds seems to favour the development 
 of auroras. 
 
 A last relation between cirrus clouds and the 
 aurora results from the fact that the annual variation 
 in the frequency of the aurora sensibly follows the 
 same course as that of halos. Tycho Brahe observed 
 this parallel march of the two phenomena, which 
 presented maxima simultaneously in 1580 and in 
 1590, years which must themselves be very near 
 those of the maxima of sun spots. 
 
 Hermann J. Klein, comparing twenty-five years 
 of observations made with the greatest care at 
 Cologne by Dr. Garthe, has shown that cirrus, cirro- 
 stratus, and cirro-cumulus, that is to say the highest 
 clouds, follow, as to their frequency, the same laws as 
 the spots on the sun. They presented minima in 
 
112 
 
 THE POLAE AURORA. 
 
 1856-57 and 1865-66, and maxima in 1850, 1858- 
 1859, and 1870 ; now the years of the minima of 
 sun spots are 1856 and 1857, and those of maxima 
 1848, 1860, and 1870. The agreement is thus as 
 satisfactory as possible ; the amount of variation is 
 moreover important; the mean annual frequency of 
 the cirrus in the years of minima is about 95, while 
 it rises to 140 in years of maxima. 
 
 Tromholt attains similar results from a comparison 
 of the frequency of auroras and that of halos. In the 
 seventeen years 1857-73 the numbers were as fol- 
 lows : — 
 
 - 
 
 Halos 
 
 Auroras 
 
 - 
 
 Halos 
 
 Auroras 
 
 1857 
 
 7 
 
 2 
 
 1866 
 
 29 
 
 13 
 
 1858 
 
 15 
 
 5 
 
 1867 
 
 18 
 
 7 
 
 1859 
 
 27 
 
 13 
 
 1868 
 
 18 
 
 5 
 
 1860 
 
 24 
 
 7 
 
 1869 
 
 24 
 
 17 
 
 1861 
 
 20 
 
 11 
 
 1870 
 
 28 
 
 22 
 
 1862 
 
 16 
 
 9 
 
 1871 
 
 47 
 
 22 
 
 1863 
 
 19 
 
 4 
 
 1872 
 
 32 
 
 18 
 
 1864 
 
 9 
 
 4 
 
 1873 
 
 36 
 
 15 
 
 1865 
 
 42 
 
 18 
 
 
 
 
 The parallehsm of the two series appears to be 
 complete, especially when we consider the difficulty of 
 these observations, which may be entirely suspended 
 during long periods of bad weather. 
 
 To conclude : an undoubted relation exists between 
 certain clouds of the cirrus class and the aurora 
 borealis ; the two phenomena are subject to the same 
 laws of periodicity, succeed each other, or even coexist, 
 their analogy being often so close that many observers 
 
RELATIONS 'WITH METEOEOLOGICAL PHENOMENA. 113 
 
 are of opinion that the appearance of the aurora 
 depends on the presence of these clouds. We shall see 
 that these facts are of great importance to the theory 
 of the aurora. 
 
 3. Relation of the aurora with the electricity of the 
 atmosphere. — It occasionally happens that certain 
 electric manifestations occur near the surface of the 
 earth at the same time as an aurora borealis. Thus 
 Brewster once observed the fire of St. Elmo on the 
 steeple of a church during an aurora. Hildebrandsson 
 also reports that Oscar II., King of Sweden, saw in 
 his youth, when navigating in high latitudes of the 
 Arctic seas, the fire of St. Elmo during a great 
 aurora borealis, though there was no other sign of 
 storm. Lastly, the ships ' Webfoot ' and ' Southern 
 Cross,' which doubled Cape Horn on September 1, 
 1859, observed the great aurora australis, of which 
 we have more than once spoken, and which was 
 visible simultaneously in the two hemispheres; a 
 violent storm then prevailed, and balls of fire were 
 seen at the extremities of the masts and yards of the 
 vessels. 
 
 These three cases are perhaps the only ones known 
 in which any manifestation of electricity was pro- 
 duced near the earth during the aurora borealis. All 
 other observations made in the most diflFerent coun- 
 tries and under the most varied conditions never give 
 anything but negative results. 
 
 As early as 1770 Van Swinden had remarked that 
 9 
 
114 THE POLAE AUEOEA. 
 
 atmospheric electricity did not appear to vary during 
 the prevalence of an aurora. In his various voyages 
 to the Arctic regions, from 1819 to 1825, Parry made 
 frequent experiments with a metal point carried on a 
 mast 85 feet high, which was placed in communication 
 with a sensitive electrometer. He never obtained any 
 electricity during the auroras. Scoresby, Sir John 
 Franklin, McClintock, Narea, &c. arrived at similar 
 negative results, as also did Poey, who observed at 
 Havana during the great auroras of August 26 and 
 September 27, 1859, and Secchi, who caused observa- 
 tions to be taken in several parts of Italy during the 
 auroras of October 24 and 25, 1870. 
 
 Eecent observations made with perfected apparatus 
 of the most sensitive description have not given better 
 results. During a period of magnetic disturbances 
 whith was observed at Paris, from April 13-20, 1882, 
 during the whole of which there were auroras on the 
 Atlantic, although none were noticed in Central 
 Europe, the register of atmospheric electricity at Paris 
 indicated, according to Mascart, no perturbation which 
 could be connected with the magnetic phenomena. 
 This was also the case on October 2 of the same year, 
 when a brilliant aurora was Been all over Central 
 Europe, even to the shores of the Adriatic. 
 
 Among all the missions which took part in the 
 International Polar Expeditions of 1882-83, the 
 Swedish mission which sojourned at Cape Thorsden 
 (Spitzbergen) is the only one which, in the northern 
 
EELATIONS WITH METEOROLOGICAL PHENOMENA. 115 
 
 hemispliere, made regular observations of the atmo- 
 spheric electricity. These observations were prosecuted 
 by Andrea, by means of a Mascart electrometer. 
 Andree found that before the appearance of an aurora 
 the positive electric potential of the air diminishes 
 abruptly, and even becomes negative, as usually 
 happens when it rains. As soon as the iaurora appears 
 the potential takes, as before, a high positive value. 
 The single case of negative electricity observed in a 
 clear sky (December 1, 1882) was followed a few 
 minutes later by an aurora borealis. 
 
 But it must be noted that the electric potential of 
 the air, especially at a short distance from the surface 
 of the earth, varies constantly in so abrupt and irre- 
 gular a manner that it would be imprudent to assume 
 any coincidence, even though these variations are 
 observed during an aurora, since they are always 
 happening. Sometimes at a station, where the sky 
 remains clear, distant rains produce a negative 
 potential, of which the cause would be unknown, if we 
 had not the total of the meteorological observations 
 over a vast region. Finally, the variations of the 
 potential in two neighbouring stations often offer no 
 resemblance. It would therefore be rash to assume 
 a relation between auroras and the electricity of the 
 atmosphere from a small number of observations 
 gathered in a single station ; such a relation could 
 only be considered as proved, if it were proved by 
 repeated observations from different stations that a 
 
116 THE POLAK AURORA. 
 
 perfect simultaneity exists between the variations of 
 the potential of the air and the different phases of the 
 aurora. 
 
 The recent experiments of Lemstroem in the 
 attempt to produce artificially the effects of the 
 aurora borealis bear on this question. These experi- 
 ments, begun in 1871, have been prosecuted especially 
 in Finnish Lapland in the neighbourhood of Sodan- 
 kyla and Kultala, during the winters of 1882-83 
 and 1883-84. 
 
 At the summit of the hill Kommattiwaara, which 
 attains a height of 426 feet, near Sodyanka, Lemstroem 
 disposed an electric apparatus composed of a wire, 
 bearing upright points at every twenty inches. This 
 wire, of which the points were turned towards the sky, 
 was arranged in an immense spiral square, covering a 
 total surface of 435 square yards, each turn of the 
 spiral being separated from the next by a distance of 
 five feet. The whole was supported on posts eight 
 feet four inches high, furnished with sulphuric acid 
 insulators. Lastly, the end of the wire, also insulated, 
 was carried to the observatory at the foot of the hill, 
 and terminated in a disc of amalgamated zinc sunk 
 in a neighbouring stream. Other similar apparatus, 
 but of smaller dimensions, were placed experimentally 
 at other points. In these conditions a galvanometer 
 situated on the course of the wire indicated an electric 
 current directed from the ground towards the atmo- 
 sphere, when the apparatus was at a short distance 
 
RELATIONS WITH METE GEOLOGICAL PHENOMENA. 117 
 
 above the surface of the ground. When, on the 
 contrary, the height was increased to a few yards a 
 current was observed to pass from the atmosphere 
 towards the ground. If two such apparatus are 
 disposed at different hfeights, the lowest being raised 
 at least nine or ten feet, and a galvanometer is placed 
 on the wire which connects them, the galvanometer is 
 traversed by a current which passes from the higher 
 of the two apparatus to the other. 
 
 Above these apparatus were seen several times 
 luminous phenomena, sometimes in the form of 
 diffused lights, sometimes, but rarely, in the form of 
 rays which seemed to dart from the points of the wire 
 towards the sky. This light showed in the spectro- 
 scope the characteristic greenish-yellow line of the 
 aurora, whereas this ray was not visible in other parts 
 of the sky. It even occurred that the line was visible 
 above the apparatus when the eye could not distinguish 
 any luminous appearance. A Holtz machine, put in 
 action in the conductor, reinforces the luminous 
 phenomena if it already exists, and may even provoke 
 it if the circumstances are favourable. Lastly, 
 Lemstroem observed three times, but only twice with 
 absolute certainty, a luminous ray, analogous to an 
 auroral ray, which started from the apparatus and 
 gave the greenish-yellow line in the spectrum. Once 
 this ray appeared during an aurora borealis in the 
 form of an arc. 
 
 Lemstroem considers these experiments very 
 
118 THE POLAE AUEOEA. 
 
 important to the theory of the aurora borealis. They 
 have provoked much criticism, notably from Tromholt, 
 who had installed a similar apparatus in Iceland and 
 obtained no results. It seems to us, however, that we 
 must admit the results obtained by Lemstroem, who 
 conducted his experiments with great care and method. 
 Yet their bearing is limited by the fact that they have 
 hitherto only succeeded with himself, and in the 
 particular locality where he prosecuted them. Vaus- 
 senat, the founder and first director of the observatory 
 of the Pic du Midi, installed in 1884, at the summit 
 of the Pic du Midi, at an altitude of 12,440 feet, an 
 apparatus similar to that of Lemstroem, but of yet 
 larger dimensions. It was composed of a cable of 
 galvanised steel wire, armed with ten or twelve very 
 sharp points to the yard. The cable was carried on 
 200 posts ten feet high, and covered a total surface of 
 765 square yards, above which were 14,000 points. 
 
 During the ten months that this apparatus re- 
 mained in situ, a luminous ray was never once seen, nor 
 even St. Elmo's fire, which constantly illuminates the 
 lightning conductors of the observatory during storms.' 
 The sole result was to produce in the neighbourhood of 
 the wire violent electric discharges, which caused serious 
 danger to the observers, the cables which put the sus- 
 pended wire in communication with the earth being at 
 
 ' St. Elmo's fire is very common at the Pic du Midi on the 
 lightning conductors ; at times, as I have seen myself, when the hand 
 is raised in the air, tlie ends of the fingers are tipped with luminous 
 balls, accompanied by the characteristic sound. 
 
RELATIONS WITH METEOROLOGICAL PHENOMENA. 119 
 
 times msnfficient to discharge the electricity which 
 accumulated on the network of points. Once, when 
 near the apparatus, Vaussenat had his eyebrows and 
 eyelashes burnt, the skin of his face was scorched, his 
 clothes singed, and the spring of his watch affected. 
 On the same day and the following days sparks, passing 
 along the communicating wire between the apparatus 
 and the laboratory, struck several persons. It therefore 
 became necessary to cut the communication and to 
 interrupt the experiment. Vaussenat was convinced 
 as a result of these attempts that the luminous effects 
 observed by Lemstroem were none other than fires of 
 St. Elmo. This conclusion appears indeed to be the 
 most probable one. As to the current observed by 
 Lemstroem to flow between the two apparatus placed 
 at different heights, it does not appear to constitute 
 a new phenomenon. The potential is known to be 
 greater as we rise in the air; two such apparatus, 
 therefore, placed at different heights, will always, if 
 there is sufficient electricity, manifest in the wire 
 which connects them a current from the higher to 
 the lower. This is an entirely natural phenomenon, 
 and in no sense implies the presence of electric 
 currents in the atmosphere, but only that of a static 
 potential, increasing with the height. In any case 
 new experiments are necessary to prove the existence 
 of electric currents in the atmosphere, and the rela- 
 tion which Lemstroem has imagined between these 
 phenomena and the polar aurora. 
 
120 THE POLAH AUEOEA. 
 
 CHAPTEE Vir. 
 
 THE ATJEOEA RELATIONS WITH TEEKESTEIAL MAGNETISM, 
 ETC., AND TELLUEIC CUEEENTS. 
 
 The relations of the aurora borealis with terrestrial 
 magnetism are of two kinds : in the first place, the 
 auroras seem to depend, for their form and position in 
 space, on the general distribution of magnetism on the 
 surface of the globe, and especially on the mean values 
 of the declension and inclination at each point. In 
 the second place, the appearances of the aurora coin- 
 cide, in a great number of cases, with the disturbances 
 which affect from time to time the various elements 
 of magnetism. We will examine successively these two 
 orders of relations. 
 
 1. Relation of the aurora with ihe general dis- 
 tribution of terrestrial magnetism. — We have more 
 than once mentioned the fact that the auroras in 
 the form of an arc are generally so oriented that 
 their summit is near the magnetic meridian. 
 Thus, in France and in the greater part of Europe, 
 when an auroral arc is seen in the northern quarter 
 of the sky, its summit is generally between the 
 north and the north-west ; it lies, on the contrary, 
 
KELATIONS WITH TEEEESTEIAL MAGNETISM, ETC. 121 
 
 between south and south-east if the aurora appears 
 on the other side of the zenith, which is, moreover, 
 much more rare. The rays, whether isolated or 
 collected into an arc, a crown, or drapery, are nearly 
 parallel to the magnetic needle, so that, according to 
 the laws of perspective, the point on which these rays 
 seem to converge in the heaven is near the magnetic 
 zenith. The force which governs the auroras appears 
 therefore. to be the same as that which the magnetic 
 needle obeys. 
 
 Yet this dependence is far from being absolute. 
 The observations of Argelander at Abo between 1823 
 and 1831 had already shown that, in that locality, the 
 summit of the arcs of the aurora is on an average ten 
 degrees to the west of the magnetic meridian. The 
 French Commission at Bossekop arrived at a similar 
 conclusion : the 226 arcs which were observed and 
 measured at that station during the winter of 1838- 
 1839 had a mean position of eleven degrees west at 
 the summit. But individual cases show a considerable 
 deviation ; 36 per cent, of the observations gave for 
 the azimuth of the summit a distance of more than 
 30° west of the magnetic meridian, and the extreme 
 variations between the azimuth of the summit are 36° 
 to the east and 90° west. Moreover, if the 226 arcs 
 are classed according to their height above the horizon, 
 it is found that their azimuth varies almost regularly 
 according to the height of the arc ; thus the summit 
 of those arcs of which the height is less than thirty 
 
122 THE POLAR AURORA. 
 
 degrees have only a mean deviation ot 6° from the 
 magnetic meridian, whereas the summit of those 
 which pass the zenith, and appear in the southern 
 half of the sky, has a mean deviation of 13°. 
 
 Bravais attempts to explain these variations by 
 supposing that the magnetic declension is not constant 
 at different degrees of altitude, but that it increases 
 with the distance from the surface of the earth. In 
 his opinion this hypothesis is the more probable that 
 in the whole of the north of Europe the direction of 
 the magnetic meridians presents a marked deviation 
 towards the east ; it may thence be supposed that this 
 deviation is caused by local causes, of which the 
 influence becomes less and less sensible with the 
 altitude above the ground, and thus a progressive 
 increase of the declension becomes apparent at greater 
 altitudes. Where the aurora is produced at a height 
 of 150 kilometres (93 miles) an increase of one degree 
 in 14 kilometres (Similes) would explain the mean 
 deviation of eleven degrees to the west of the magnetic 
 meridian manifested by the auroral arcs. 
 
 This hypothesis involves consequences which 
 render it very difficult of acceptance. For, as we have 
 said, the deviation of the summit of the arcs with 
 regard to the magnetic meridian increases with the 
 angular height of these arcs. To explain this varia- 
 tion it would therefore be necessary to suppose in 
 addition that the absolute height of the arcs increases 
 with their angular height; now this new hypothesis 
 
EELATIONS WITH TERRESTRIAL MAGNETISM, ETC. 123 
 
 would give for those arcs of which the summit is on 
 the southern half of the horizon so great an absolute 
 height that these arcs must have been visible in the 
 centre and even in the south of Europe, which was 
 not the case. 
 
 Eetaining the first hypothesis (increase of magnetic 
 declension with the altitude) we might, to replace the 
 second (increase of the absolute height of the arcs 
 with their angular height), suppose that the polar 
 aurora is at a less altitude in the atmosphere over the 
 sea than over the continent. At Bossekop, as a 
 consequence of the relative positions of the sea and 
 land, the arc would be less high in its eastern half 
 than at the other, and thus asymmetrical. Starting 
 from the zenith the apparent summit of the arcs 
 would then be deviated more and more towards the 
 east in the degree that the arcs were at a less height 
 above the horizon, towards the north as towards the 
 south. The summits of the arcs would thus be 
 nearer the magnetic meridian in the northern half of 
 the heaven, and further from it in the southern half, 
 which appears to agree with the observations. We 
 must add, however, that this explanation would not 
 apply in the case of other countries, Spitzbergen for 
 example, where, however, the mean deviation of the 
 summit of the arcs is the same as at Bossekop. 
 
 In conclusion, Bravais thinks that all these causes 
 act simultaneously, and that they co-operate in 
 producing the observed deviations. But none of 
 
124 THE POLAE AUEOEA. 
 
 these hypotheses can be verified, even indirectly, and, 
 if they offer an approximate explanation of the mean 
 deviation of the auroral arcs at different heights, they 
 are entirely insufficient to account for the considerable 
 deviations which are observed when, instead of con- 
 sidering the average, each aurora is studied separately. 
 Thus on January 16, 1839, Bravais observed an arc 
 of which the summit was 90° to the west of the 
 magnetic meridian ; and on January 21 another arc 
 had its summit 36° to the east of the same meridian. 
 Observations taken in other regions have also 
 shown that the azimuth of the summit of the arcs 
 does not as a rule coincide with the magnetic 
 meridian. Thus Nordenskioeld, during the wintering 
 of the ' Vega ' in the north-west of Behring Strait, 
 found that the summit of the arcs was very near the 
 geographic meridian, whereas the magnetic declension 
 was 20°. Two auroras observed far to the south, at 
 Benares (1847) and at Macao (1838), had their 
 summit 20° east of the magnetic meridian. The 
 observations of the International Polar Expeditions 
 of 1882-83 furnished similar results. At Jan Mayen, 
 for example, the summit of the arcs was on an 
 average four degrees east of the magnetic meridian ; 
 at Spitzbergen the mean deviation, out of 371 mea- 
 surements, was more than eleven degrees in the 
 same direction. In Central Europe the coincidence 
 appears more perfect. Finally, the observations 
 made at Hobartstown and Melbourne give a mean 
 
RELATIONS WITH TEEEESTEIAL MAGNETISM, ETC. 125 
 
 deviation for the summit of the aurora of nine or 
 ten degrees to the east of the magnetic meridian. 
 
 The study of the orientation of the crowns and of 
 the auroral rays leads to analogous results to those 
 furnished by a study of the arcs. In general, the 
 point where the rays converge, or what comes to the 
 same thing, the centre of the crown, is very near the 
 magnetic zenith. Forty-three observations of crowns 
 taken at Bossekop gave between these two points a 
 mean distance of less than a degree, which is about 
 the amount of probable error in the observations ; 
 the coincidence may therefore be regarded as perfect. 
 But if we consider individual observations we find 
 great divergences in detail, as in the case of the arcs. 
 Thus on January 20, 1829, at Bossekop, the con- 
 verging point of the rays of an aurora was at 15° 
 from the magnetic zenith ; on two other occasions 
 the deviation was 12°. 
 
 In spite of these accidental deviations the mean 
 position of the centre of the crowns seems to be at 
 very little distance from the magnetic meridian in 
 all countries where trustworthy observations are 
 sufficiently numerous, as in France, England, Central 
 Europe, &c. Thus on October 25, 1870, Heis found 
 at Munster that the centre of the crown was exactly 
 in the magnetic meridian and 65° from the horizon, 
 while the magnetic inclination was 67°. The 
 centres of the two crowns observed by Winnecke 
 at Pulkova, April 34, 1859, and December 14, 1862, 
 
126 THE POLAB AUEOEA. 
 
 had respectively a height of 69° and 72°, the inclina- 
 tion being a little less than 71°. In Spitz bergen, 
 according to the observations of Palander in 1872 
 and 1873, the centre of the crowns was only on an 
 average two degrees lower than the magnetic zenith ; 
 in the same country Carlheim Gyllenskioeld found in 
 1882-83 for the height of the centre of the crown, 
 after eighty-seven measurements, 79° 55', the magnetic 
 inclination being 80° 35'. The same coincidence is 
 observed in the southern hemisphere ; thus the centre 
 of the crown observed at Melbourne during the 
 great aurora of September 2, 1859 (fig. 15), was at 
 one degree of angular distance from the magnetic 
 zenith. 
 
 The position of the centre of the coreal crown 
 at Bossekop was not in perfect agreement with the 
 hypothesis suggested by Bravais to account for the 
 deviation of the summit of the auroral arcs to the 
 west of the magnetic meridian, which we have in- 
 dicated above. The mean position of the centre of 
 the crowns was more than three degrees to the west 
 of the vertical plane perpendicular to that which 
 marks the mean direction of the auroral bands or of 
 the arcs, and this difference is certainly greater than 
 possible errors of observation. We must therefore 
 admit either that the mean orientation of the bands 
 of the aurora is not perpendicular to the magnetic 
 meridian, or that the direction of the rays is not 
 rigorously parallel to the magnetic needle. As the 
 
RELATIONS WITH TERRESTRIAL MAGNETISM, ETC. 127 
 
 distance between the centre of the crowns and the 
 magnetic zenith is less than the deviation between the 
 summit of the arcs from the magnetic meridian, it 
 appears more rational to admit that the arcs or bands 
 are not perpendicular to this meridian. 
 
 The conclusion of all that precedes is that the 
 magnetic forces of the earth certainly play the 
 principal part in the orientation of the aurora 
 borealis. The . arcs or bands tend to dispose them- 
 selves nearly perpendicularly to the magnetic 
 meridian ; and the direction of the rays is sensibly 
 parallel to the magnetic needle. Bat other causes 
 may intervene and produce notable deviations in the 
 arcs or the rays. We shall see later that the most 
 satisfactory theory which has yet been proposed for 
 the aurora borealis accounts perfectly, far better than 
 the hypotheses of Br avals, for the mean deviation of 
 the summits of the auroral arcs from the magnetic 
 meridian ; it only remains therefore to account for 
 the abnormal deviations, such as those which trans- 
 port the summit of the arcs far from their mean 
 position, as in the examples which we have given. 
 The causes of these accidental deviations are yet un- 
 known ; but it seems to us that they should be sought 
 in meteorological conditions. Different parts of the- 
 atmosphere, even at no great distances from each 
 other, vary greatly in temperature and humidity. The 
 electric discharges which constitute the aurora 
 borealis encounter therefore at a given moment 
 
128 THE POLAR AUEORA. 
 
 strata which are unequally conductive ; hence a cause 
 of that want of symmetry observed in the form of the 
 auroras, and probably of the deviations in direction 
 which we have indicated, and which are sometimes 
 considerable. 
 
 As we have said, in a previous chapter, no very 
 distinct relation has yet been proved between the 
 aurora borealis and meteorological conditions; but 
 this is perhaps because' a direct relation has been 
 sought between the two phenomena, whereas meteoro- 
 logical conditions may very likely influence, not 
 the production of the aurora, but its form and 
 position. 
 
 2. Relation of the aurora with magnetic distur- 
 bances. — Independently of the phenomenon of the 
 direction of the aurora borealis, in which the influ- 
 ence of terrestrial magnetism plays a chief part, the 
 production itself of the auroras is associated, at least 
 in many cases, with the disturbances which manifest 
 themselves at irregular and variable intervals in the 
 value of the different magnetic elements. 
 
 It was at Upsala in 1741 that Celsius and Hiorter 
 pointed out for the first time the simultaneity of an 
 aurora borealis and disturbances in the magnetic 
 declension. Between 1741 and 1747 Hiorter noted 
 forty-six examples of this coincidence. He recognised, 
 however, that the two phenomena might occur 
 separately, and that magnetic disturbance accom- 
 panied especially those auroras which were seen at 
 
EELATIONS WITH TEEEESTRIAL MAGNETISM, ETC. 129 
 
 Upsala to the south of the zenith. On the request, of 
 Celsius, Graham pursued in London a series of 
 corresponding observations to those at Upsala, and it 
 was thus discovered that the magnetic disturbances 
 occurred as a rule on the same day at the two 
 stations. 
 
 These observations were afterwards continued by 
 Wargentin, Canton, and Wilcke. The last discovered 
 that every time, or almost every time, that magnetic 
 disturbance is noted, it is accompanied by an aurora 
 boreaUs, but that the converse does not hold ; that is 
 to say, that auroras are often seen without any pertur- 
 bation of the magnetic needle. 
 
 Wilcke also studied, between 1741 and 1774, the 
 relations of the aurora borealis with the magnetic 
 inclination ; he was the first to note the coincidence 
 of the centre of the crown with the magnetic zenith, 
 and showed that during the auroras the inclination 
 is disturbed as well as the declination. Thus he 
 observed irregular variations in the inclination which 
 sometimes attained to a degree ; he remarked at the 
 same time that the centre of the crown altered its 
 position in the sky in the same direction as the 
 magnetic dipping iieedle.' Numerous observers, 
 among whom we may mention Van Swinden, Cassini, 
 Gilpin, &c., verified anew the discoveries of their 
 predecessors. 
 
 ' See on this question Wijkander, ' Ueber die magnetischen 
 Storungen und ihren Zusammenhang mit dem Nordlichte ' {Zeit- 
 schrift der Ssterreichischen Gesellschaft filr Meteorologie, xii., 1877). 
 10 
 
130 THE POLAE ATJEOEA. 
 
 In observations taken at Montmorency, near 
 Paris, Coote remarked, in 1780, an interesting fact, 
 of which we shall have more to say later, for it has 
 a great importance in determining the nature of 
 the relations which exist between the aurora and 
 magnetic disturbances; it is that the magnetic dis- 
 turbances seem to be the earliest in order of time, 
 and that the magnetic needle sometimes begins to. 
 be agitated an hour before the appearance of an 
 aurora. 
 
 Lastly, the relations of the aurora with the dis- 
 turbances in the magnetic force itself, and not only 
 with those in the direction of the needle, were 
 discovered in 1806 by Humboldt. He announced 
 that the horizontal factor in magnetic intensity 
 diminishes during the prevalence of an aurora. 
 This proposition has since been verified, notably by 
 Hansteen, Farquharson, and . Fos ; Hansteen also 
 thought that the horizontal intensity increased con- 
 siderably some time before the appearance of an 
 aurora, and then diminished as soon as the aurora 
 became visible ; the degree of this variation seeming 
 to him to be in direct relation with the luminous 
 intensity of the aurora. Lastly, Hansteen remarked 
 that the magnetic perturbations sometimes last a long 
 time ; the intensity has often not recovered its initial 
 value more than twenty-four hours after the be- 
 ginning of the disturbance. 
 
 The magnetic association founded by Gauss and 
 
RELATIONS WITH TERRESTRIAL MAGNETISM, ETC. 131 
 
 Weber in 1834, and the stations organised by Sabine 
 in a certain number of English colonies, greatly 
 increased the number of examples of coincidences 
 between the polar auroras and perturbations in the 
 three elements of terrestrial magnetism : declination, 
 inclination, and intensity. But they also testify to 
 the complexity of the question. For though the 
 great magnetic perturbations, which occur simul- 
 taneously in the two hemispheres, seem to be always 
 accompanied by very extensive auroras, this is not 
 the case with more ordinary disturbances. These 
 often appear to be due to local causes ; they are not 
 noticed at the same time in the two hemispheres, or, 
 in the same hemisphere, are not manifested at the 
 same time in Europe and America. Sometimes, 
 even, this absence of concord may be remarked in 
 stations much nearer to each other : thus, the per- 
 turbations remarked by the French Commission at 
 Bossekop had often no relation with those of Central 
 Europe; the difference was especially frequent in 
 the variations in the horizontal factor in magnetic 
 intensity. It was then recognised that these local 
 perturbations are not as a rule accompanied by 
 auroras. 
 
 A great number of analogous observations might 
 be mentioned; we will only indicate the principal 
 results obtained by Weyprecht at the time of 
 the expedition to Franz Josef Land on board the 
 ' Tegetthof.' 
 
132 THE POIiAB AUEOEA, 
 
 The magnetic perturbations which accompany the 
 aurora borealis are greater in proportion to the 
 apparent proximity of the aurora to the spectator. 
 Thus motionless arcs and faint auroras, or those 
 with slow movements, are generally unaccompanied 
 by the slightest agitation of the magnetic needle; 
 magnetic perturbation is, on the contrary, very marked 
 during auroras with distinct outlines, and those 
 which present luminous rays of a defined character 
 and rapid movements; the greatest deviations of 
 the compass correspond to the appearance of great 
 rays, coloured red and green, which flash suddenly 
 like lightning. 
 
 Finally, during all the perturbations observed by 
 Weyprecht, the needle was displaced towards the 
 east, the horizontal intensity diminished, and the 
 vertical intensity increased. According to Weyprecht, 
 variations in the contrary sense, which are very rare, 
 should be regarded solely as phenomena of reaction 
 and not as true perturbations. 
 
 In conclusion, as long as we consider only mean 
 latitudes, such as Central Europe and France, that is 
 to say, countries where the aurora has generally a 
 great altitude and extension, we find a very satis- 
 factory coincidence between the aurora borealis and 
 magnetic perturbations. We must not even assume 
 a priori that the apparent absence of auroras during 
 violent magnetic disturbances is an argument against 
 this relation. For Arago has shown that if the 
 
RELATIONS WITH TEERESTEIAL MAGNETISM, ETC. 133 
 
 aurora sometimes appears to be absent during mag- 
 netic disturbance, it is often because it is too distant, 
 and is entirely below our horizon ; but it is then 
 visible in more northern regions. 
 
 On the other hand, the relations between auroras 
 and magnetic disturbances seem to be far less certain 
 in high latitudes. There, perturbations are often 
 
 Fia. 16. — Chaet of the Frequency op the Aurora Bohealis. 
 
 noticed to which no aurora corresponds ; often on the 
 contrary auroras are seen, before and during which 
 the compass needle remains perfectly still. The 
 relative independence of the two orders of phenomena 
 is especially manifest in those regions which are 
 situated within the zone of maximum frequency (see 
 fig. 16), and in a still more marked degree in the 
 
134 THE POLAE AX7E0EA. 
 
 countries within the line of neutral direction, where 
 the frequency of the auroras to the north is lees than 
 that of those to the south. 
 
 Thus, in his two winters spent respectively at 
 Melville Peninsula and Port Bowen, not far from the 
 magnetic pole, Parry never remarked any relation 
 between the appearance of the aurora and the move- 
 ments of the compass needle. Though Eoss obtained 
 a different result in the same regions and noted several 
 times the coincidence of the two phenomena, this 
 coincidence appears rather to be the result of chance, 
 for McClintock observed it only five times in two con- 
 secutive winters, which confirms Parry's results. Kane 
 arrived at a similar conclusion ; during the two winters 
 of 1853 and 1855 which he spent at Port Van Eans- 
 selaer, at the extreme north of Greenland, he never 
 once observed magnetic perturbation during an aurora 
 borealis. Bessels, who sojourned yet a little further 
 to the north, at the time of the expedition of the 
 'Polaris,', noted variations in the declination during 
 one aurora only ; but that was the quite exceptional 
 aurora of February 4, 1872, of which we have already 
 spoken more than once, and which seems to have 
 enveloped the whole earth, exce])t the equatorial zone. 
 Finally, during the wintering of the ' Alert ' and the 
 ' Discovery ' in 1875-76, in the extreme north of 
 Smith Strait, no relation was remarked between the 
 aurora and magnetic disturbance. 
 
 The fact that in the Arctic regions the aurora 
 
RELATIONS WITH TEEEESTEIAL MAGNETISM, ETC. 135 
 
 borealis is not, as a rule, accompanied by magnetic 
 perturbation, is the more remarkable that magnetic 
 perturbation displays in these regions an extraordinary 
 frequency and extent. In mean latitudes, in France 
 and Central Europe, the alterations in declination 
 hardly exceed a fraction of a degree ; they very rarely 
 attain to one degree, and there is no example of any 
 perturbation having deviated the compass needle as 
 much as two degrees from its normal direction. In 
 Greenland and in the American Arctic regions, on the 
 contrary, perturbations of eight to ten degrees are 
 not uncommon. On December 24, 1858, McClintock 
 observed at Port Kennedy movements of the needle 
 which attained to a total amount of fifteen degrees. 
 During the expedition of the ' Polaris,' Bessels noted a 
 deviation of twelve degrees on February 4, 1872, a 
 little before the appearance of the great aurora of 
 that day ; he remarked, moreover, that on that occa- 
 sion the magnetic disturbance preceded the aurora by 
 about six hours. Finally, at Lively, on Disco I. 
 (west coast of Greenland) 0. T. Sherman observed, 
 between August 11 and 18, 1880, a variation of 
 20° 40' in the declination. 
 
 From all this we may conclude that there is no 
 necessary connection between the aurora borealis and 
 magnetic perturbation in the Arctic regions, that is to 
 say, precisely where magnetic disturbance is most 
 frequent and most considerable. This conclusion 
 rests on an indisputable fact, the frequently observed 
 
136 THE POLAR AUEOEA. 
 
 absence of magnetic perturbation during the prevalence 
 of an aurora. 
 
 For, as we have said above, it is not possible, in 
 strictness, to conclude anything from the apparent 
 absence of an aurora during magnetic disturbance; 
 but it is quite otherwise in the case of an absence 
 of magnetic perturbation during an aurora j this 
 absence, already noted in Europe, but exceptionally, 
 by Wilcke, Bravais, and others, becomes the rule in 
 Greenland and in the Arctic regions of the North of 
 America. 
 
 These facts are of prime importance to the theory 
 of the production of the aurora borealis. Many authors 
 have suggested the aurora borealis as the cause of 
 magnetic disturbance. Bravais, in particular, though 
 he recognised that the aurora obeys with respect to 
 its position the regular laws of terrestrial magnetism, 
 thought that this dependence was reversed in all that 
 concerns magnetic perturbation, and attributed the 
 latter to the direct action of the aurora. This theory 
 is disproved by later observations, and in two distinct 
 ways : first of all, because in the Arctic regions auroras 
 are frequently seen while the compass needle remains 
 quite stUl ; and in the second place, because when the 
 two phenomena are manifest concurrently, it seems 
 that the magnetic disturbance usually precedes the 
 aurora. We have already indicated observations of 
 this nature, among others those of Cotte, Hansteen, 
 and Bessels ; we may also mention the great aurora 
 
RELATIONS "WITH TEERESTEIAL MAGNETISM, ETC. 137 
 
 australis of August 29, 1859, which was accompanied 
 at Melbourne by violent magnetic perturbations (1° 9' 
 for the declination) and by interrupted telegraphic 
 communications ; now these disturbances preceded 
 the aurora, which only appeared at the moment 
 when the telegraphic communication had begun to 
 improve. 
 
 In conclusion, it seems to us impossible, from all 
 the preceding arguments, to hold that the aurora 
 borealis causes magnetic perturbation, although that 
 is the most generally received opinion. We think 
 rather that magnetic disturbance, or else telluric 
 currents, determine the production of some at least of 
 the auroras. It seems to us, moreover, that most of 
 the difficulties which we have pointed out would dis- 
 appear, notably those which result from the indepen- 
 dence of the aurora and magnetic perturbations in 
 certain regions, if we admitted the existence of two 
 distinct phenomena comprised under the generic name 
 of aurora borealis. The one, comprehending the auroras 
 which have a great extent, that is to say, almost all 
 the auroras of mean latitudes and some of those of 
 the Arctic regions, manifests itself at a great height 
 in the atmosphere, and is always accompanied by 
 magnetic disturbance. This is no longer the case 
 with the auroras of lower altitudes, of small extent, 
 and so to speak local, which are only rarely seen out- 
 side high latitudes. Both kinds of polar auroras are, 
 according to this theory, incapable of acting them- 
 
138 THE POLAR AURORA. 
 
 selves on the magnetic needle ; on the contrary, the 
 former are, as it were, the reflection in the atmosphere 
 of the interruption in the magnetic or electrical 
 equilibrium of the earth. We are thus brought back 
 by the study of the relations between the polar aurora 
 and terrestrial magnetism to the same conclusion as 
 that drawn from the consideration _ of the physical 
 characteristics of auroras, of their altitude and 
 periodicity ; that is to say, to the belief that in the 
 appearances summed up under the general name of 
 polar aurora, we have two phenomena distinct in all 
 their properties and even in their origin, which it 
 would be desirable to consider separately henceforward 
 if we would arrive at more accurate notions as to their 
 nature and the laws which govern them. 
 
 3. Relations between the polar aurora and telluric 
 currents. — Matteucci, at the time of the aurora borealia 
 of October 28, 1848, remarked the coincidence of this 
 phenomenon with interruptions in telegraphic com- 
 munications, produced by telluric currents. This is 
 the name given to currents which manifest them- 
 selves spontaneously from time to time in wires 
 isolated throughout their length and communicating 
 at either end with the earth. Telegraphic wires are 
 precisely such conducting lines, and, thanks to the 
 length and multiplicity of these lines in all directions 
 over the whole surface of the globe, we possess most 
 extensive information about this class of phenomena. 
 The telluric currents which thus pass along the 
 
RELATIONS WITH TERRESTRIAL MAGNETISM, ETC. 139 
 
 telegraphic wires of some length are generally of 
 sufficient intensity to set the electric call bell in 
 motion, and sometimes absolutely to prevent the 
 transmission of messages ; when they are exception- 
 ally strong they may cause sparks and discharges of 
 sufficient force to throw the mechanism out of gear, 
 and even to be ^ source of danger to the personnel. 
 
 These spontaneous currents are of two distinct 
 kinds : some occur when a violent storm takes place 
 in the region traversed by the telegraphic wire ; these 
 have no relation with the aurora ; but it is quite 
 otherwise with the telluric currents proper, which 
 manifest themselves independently of any storm, and 
 are, moreover, distinguished from the former by 
 marked characteristics. 
 
 When a cloud charged with electricity approaches 
 a telegraphic line, the wire is charged, as it were, by 
 influence, and the electrisation alters when the cloud 
 moves off. If the cloud discharges itself suddenly, at 
 the moment of a lightning flash, for instance, the 
 wire instantly returns to the neutral state, and a 
 momentary current is observed to traverse the 
 apparatus at the stations. If one end of the line be 
 isolated the phenomena remain the same at the other 
 extremity, and the currents are even more intense, 
 since the wire can only be charged and discharged 
 from the one end. Finally, these currents, which are 
 produced by simple influence, evidently cannot occur 
 in subterranean or submarine cables ; nor are they 
 
140 THE POLAE AURORA. 
 
 observed in those wires carried through the air which 
 are provided with a conducting envelope communica- 
 ting with the soil. 
 
 It is very different with telluric currents proper, 
 which accompany magnetic perturbations and 
 auroras. These currents cease when one end of the 
 wire is isolated ; they are only manifested in single 
 lines which have their return by the earth. It is not 
 therefore an electrisation by influence which is 
 produced in the wire, but a true current, identical 
 with the currents produced by a battery, and it 
 results from the fact that the two points of the earth 
 where the extremities of the wire terminate are in 
 contact with different electric potentials. These 
 currents may therefore occur in subterranean or sub- 
 marine cables, as well as in lines above ground, as is 
 perfectly verified by experience. Lastly, their intensity 
 varies in direct ratio with the length of the hne. 
 
 The simultaneity of auroras and these telluric 
 currents, discovered in 1848 by Matteucci, was clearly 
 established at the time of the great aurora observed 
 on the nights of September 1 and 2, 1859, over the 
 whole of the American continent, dayhght alone, 
 probably, preventing its being visible in Europe. 
 Very interesting observations were made in France 
 at the same date by Bergon and Blavier ; we quote 
 from the notes on the subject published by Blavier,' 
 the following details : 
 
 ' Annuavre de la SocUti MiUorologijue de France, vol. vii. 1859. 
 
RELATIONS WITH TEEEESTKIAL MAGNETISM, ETC. 141 
 
 ' At all the telegraphic stations in France the service 
 was impeded during the whole of September 2, but 
 especially at two periods of the day, from 4.30 a.m. to 
 9 A.M., and from noon to 3 p.m. These two periods 
 were the same at all stations, and the greatest disturb- 
 ances took place exactly at the same hours, at 7 a.m. 
 and at 2 p.m. The phenomenon consisted in a current 
 producing continuous attraction of the, armatures of 
 the electro-magnets ; a galvanometer introduced into 
 the circuit showed that the current changed its direction 
 at varying intervals of time, of at least two minutes' 
 duration. Towards 7 a.m. and 2 p.m. these currents 
 were so strong that when the wire was isolated, and a 
 conducting substance presented to it, it gave off vivid 
 sparks. The currents manifested themselves in all 
 directions ; they seem, however, to have been more 
 marked on the lines which went from north to south. 
 The longest wires always showed the greatest dis- 
 turbances.' The same day telluric currents were also 
 observed in the greater part of the two hemispheres, 
 in Switzerland, in Germany, in the British Isles, in 
 North America, and throughout Australia. In the 
 United States, in particular, they were so strong that 
 for about two hours it was possible to send messages 
 from Boston to Portland, and vice versa without any 
 battery, using only the telluric current. 
 
 On May 30, 1869, during the aurora borealis 
 which was visible from 7 to 9 p.m., Heer observed 
 that out of the sixteen lines which terminated in the 
 
142 THE POLAE AURORA. 
 
 telegraphic office at Basle, six were almost useless 
 during the two hours that the phenomenon lasted ; on 
 the others- the telluric currents were not strong 
 enough absolutely to interrupt communication. 
 
 Similar coincidences were also observed during 
 the auroras of April 5 and October 24, 1870 ; and 
 the telluric currents attained an extraordinary de- 
 velopment during the aurora of February 4, 1872, 
 which we have mentioned as one of the most exten- 
 sive known ; it was seen in the whole of the West of 
 Asia, in the North of Africa, throughout Europe, and 
 on the Atlantic as far as Florida and Greenland ; at 
 the same time an aurora was observed in part of the 
 southern hemisphere. The disturbances in telegraphic 
 communication were not less extensive, and were 
 observed with great care, in great part of Europe. In 
 Paris they began on the lines directed eastwards, those 
 to Germany and Austria, then on that to Switzerland. 
 In Germany all the lines were affected, and com- 
 munication was for a long time impossible between 
 Cologne and London ; in that country the most 
 marked perturbations were observed on the lines 
 directed east and south-east. These currents were 
 also observed in Italy and in Turkey, on the long 
 line from Valona to Constantinople. At the same 
 time many of the submarine cables were so affected 
 as to prevent the transmission of any messages ; the 
 disturbance was especially marked on. the line from 
 Libbon to Gibraltar, on the Mediterranean cable, on 
 
RELATIONS "WITH TERRESTRIAL MAGNETISM, ETC. 143 
 
 the line from Suez to Aden, and from Aden to 
 Bombay, and finally along the Transatlantic cable 
 from Brest to Duxbury. 
 
 Lastly, during the great aurora of November 17, 
 1882, the telluric currents observed in England were, 
 according to Preece, five times as strong as the 
 current usually employed in telegraphy. Communi- 
 cation was interrupted as long as the disturbance 
 lasted. 
 
 These examples will suffice to show the close rela- 
 tion existing between polar auroras and telluric 
 currents ; but it is not possible to go further and for- 
 mulate this relation in precise terms. For, as a 
 rule, telluric currents are observed in a very insuffi- 
 cient manner, and only when they are sufficiently 
 strong to hamper telegraphic communications. In 
 some few observatories there has been an attempt to 
 organise a regular study of these currents, but as a 
 rule too short a line has been employed, so that no 
 general law has yet been established as a result of 
 these observations. 
 
 There is reason to hope that this want will soon 
 be supphed. The central meteorological office of 
 France has lately organised at the Observatory of the 
 Pare Saint-Maur, near Paris, a regular observation of 
 the telluric currents, which will be prosecuted hence- 
 forward at the same time as that of terrestrial magne- 
 tism. Thanks to the valuable aid of the Adminstra- 
 tion of the telegraph service three special lines have 
 
144 THE POLAE AUEOEA. 
 
 been constructed and reserved to this study ; one lies 
 exactly north and south, from Eosny-sous-bois to 
 Limeil, and has a length of 14,800 metres (ten 
 miles) ; the second, which is the same length, lies 
 from west to east, from Joinville-le-Pont to Croissy. 
 The third line is a closed circuit embracing a little 
 less than twelve square kilometres which corresponds 
 to a diameter of about 3,900 metres (nearly two and 
 a half miles). On these three lines at the Observa- 
 tory are placed galvanometers, whose indications are 
 registered photographically as in the case of the mag- 
 netic instruments. These observations began in 
 1893, and have already led to interesting results as 
 to the relations which exist between telluric currents 
 and magnetic perturbations. We quote these results 
 from the notice published by M. Moureaux.' 
 
 The variations of the telluric current of the line 
 which lies from east to west are of the same kind as 
 those of the horizontal factor in the terrestrial mag- 
 netic force. The general appearance of the two 
 curves is exactly the same. As M. Wild had already 
 noted at Pavlovsk, a current from east to west cor- 
 responds always to an increase in the horizontal 
 factor, and inversely. The relation between the 
 currents of the line from north to south and the 
 variation in magnetic declination seems less simple ; 
 the perturbations are indeed similar in extent in the 
 
 ' Annales du bureau central mitiorologique de Francepour 1893, 
 vol. i. 
 
EELATIONS WITH TEEBESTELy:- MAGKETISM, ETC. 145 
 
 two curves, but the deviations are now in the same 
 direction and now in opposite directions; yet a 
 current from the north to the south generally corre- 
 sponds to an increase of declination, and inversely. 
 
 Airy's observations at Greenwich and Wild's at 
 Pavolsk had seemed to indicate that telluric cur- 
 rents always preceded by some minutes the cor- 
 responding magnetic variations. This law is not 
 always verified at Saint Maur; the currents often 
 precede the magnetic variations by two or three 
 minutes; but on the other hand the simultaneity 
 of the two phenomena is often perfect. The question 
 requires therefore further study. No aurora borealis 
 has yet been observed in the neighbourhood of Paris 
 since the study of the telluric currents has been regu- 
 larly organised. 
 
 If a relation of cause and effect is proved to exist 
 between the aurora borealis and telluric currents it 
 remains to be discovered which of the two phenomena 
 is the cause of the other. We have just seen that 
 there is an intimate relation between telluric currents 
 and magnetic disturbance, so much so that it is 
 probable that one of the two phenomena is the cause 
 of the other, or that they are both dependent on some 
 yet unknown cause. In our study of the relations 
 of the aurora with magnetic perturbation we have 
 shown that we cannot consider the latter to be depen- 
 dent on the auroras, the contrary relation being the 
 more probable one. It is therefore probable also that 
 11 
 
146 THE POLAE AUEOEA. 
 
 the magnetic perturbations or the telluric currents 
 are the principal phenomenon which determines the 
 production of auroras, or, at least, of those grea,t 
 auroras which are visible in mean latitudes. This 
 opinion has been advocated by Kuhn (1861) and 
 Balfour Stewart (1869), among others; the latter 
 compares the earth to the centre of a Euhmkorffs 
 coil, of which the circuit is composed by the higher 
 strata of the atmosphere. Electric movements are 
 produced in these strata when terrestrial magnetism 
 or the telluric currents undergo rapid variations. 
 Now, as we have seen above, according to the obser- 
 vations of Blavier during the polar aurora of 1859, 
 telluric currents changed their direction alternately 
 at frequent intervals, a condition eminently favour- 
 able to the production of induction. It is therefore 
 very probable that certain polar auroras at least are 
 merely a secondary phenomenon, of which the imme- 
 diate cause is to be found in telluric currents or in 
 the perturbations of terrestrial magnetism. We shall 
 return to this point when we come to discuss the 
 theory of the polar aurora. 
 
U7 
 
 CHAPTEE VIII. 
 
 THEORIES OF THE POLAR AUEOEA. 
 
 Few phenomena have given rise to so great a number 
 of hypotheses and theories as the polar aurora ; 
 we find them already in Greek authors, from 
 Anaxagoras, Anaximenes, and Aristotle, and it would 
 be easy to fill a volume with the mere enumeration 
 of these attempts at a theory, without discussing 
 them. We will not therefore try to sketch the 
 history of these opinions, but confine ourselves to a 
 statement of the principal ones, and especially those 
 which have had most influence on the study of the 
 aurora. These theories may be classed under four 
 heads : cosmic, optic, magnetic, and electric theories. 
 1. Cosmic theories. — In the cosmic theories of the 
 polar aurora this phenomenon is attributed to causes 
 completely exterior to our globe. Of the numerous 
 theories of this nature, the most famous is that of 
 Mairan, who wrote his * Treatise ' on the aurora 
 borealis, to which we have so often referred, to ex- 
 pound and defend it. Mairan attributes the aurora 
 to the zodiacal light, a whitish light like that of the 
 
148 THE POLAE AURORA. 
 
 Milky Way, which is seen in the heavens at certain 
 seasons of the year, in the form of a long beam of 
 light extended along the zodiac. The first serious 
 study of this phenomenon was that of Cassini, begin- 
 ning in 1683 ; his work was continued in the follow- 
 ing century, notably by Mairan, and it was recognised 
 that, according to all appearances, the zodiacal light 
 is a very much flattened ring, formed of material 
 particles, surrounding the solar equator. The radius 
 of this ring varies with the season, is always very 
 large, and may exceed that of the orbit of the earth. 
 
 According to Mairan the aurora borealis is pro- 
 duced when the earth comes in contact with the 
 zodiacal light ; the matter of this zodiacal light, yield- 
 ing to the attraction of the earth, falls into our 
 atmosphere and is set on fire, ' either by itself, or by 
 its collision with the particles of the air, or by the 
 fermentation occasioned by its mixture with the air.' 
 Starting from this hypothesis, Mairan explains in an 
 ingenious manner the various appearances and the 
 periods of the aurora borealis. 
 
 This explanation appears to have been adopted at 
 the time with enthusiasm. According to Fester, 
 Mairan had ' lit a torch which illuminates the origin 
 and the causes of this phenomenon.' In his treatise 
 on meteorology (1774) Cotte speaks of ' the admirable 
 agreement which exists between all the parts of this 
 system and the result of the observations which the 
 table of the aurora borealis presents to us.' 
 
THEOEIES OF THE POLAE AURORA. 149 
 
 Nevertheless, the theory of Mairan encountered 
 from the first some resolute opponents, especially 
 Euler and Lambert. A capital objection was early 
 made, viz., that if the aurora borealis was produced 
 by causes external to the earth it would present 
 an apparent movement from east to west, like tlie 
 other celestial bodies. An analysis of all the 
 Bossekop observations led Bravais to the opposite 
 conclusion ; not only the movement from east to west 
 is not the prevailing one in the aurora borealis, but the 
 inverse movement is the most frequent. So also the 
 position of the earth in its orbit has no influence on 
 the movements of the aurora. It must be added that 
 the hypothesis of a cosmic origin renders no account 
 of the regular daily variations which are observed in 
 the forms of the aurora. ' These remarks,' concludes 
 Bravais, ' appear to me destructive of any hypothesis 
 which would attribute the aurora borealis to a cosmic 
 matter originally foreign to our globe. How under 
 this hypothesis can we account for the evident 
 diurnal period which is followed by the forms of the 
 aurora, and the absence of any similar period in its 
 movements? How can we understand that the 
 variation is found there where it should not exist, 
 and is absent where it should on the contrary be 
 found ? ' 
 
 These objections finally dispose of all cosmic 
 theories, and force us to see in the aurora borealis a 
 purely terrestrial phenomenon. 
 
150 THE POLAH AUEOEA. 
 
 We must here note a singular coincidence which 
 could not, of course, be known in Mairan's time, but 
 which would have singularly increased the confidence 
 which his theory inspired. We have seen that the 
 light of the aurora is specially distinguished in the 
 spectroscope by a brilliant yellowish green line, which 
 has not yet been referred to any known body. Now 
 this line is found also in the spectrum of the zodiacal 
 light, as has been proved by Angstroem, Vogel, and 
 Lockyer among others. We cannot thence conclude 
 the identity of the two phenomena ; but if some day 
 the source of the greenish-yellow Une of the aurora is 
 discovered, it will be at the same time a precious 
 indication of the constitution of the zodiacal light. 
 
 Cosmic hypotheses have often been combined with 
 other theories to explain the aurora ; we shall givd 
 some examples of these in our examination of the 
 magnetic theories. The objections which render the 
 purely cosmic theories inacceptable evidently apply 
 equally to mixed theories. 
 
 Though it is impossible to admit that auroras are 
 due to cosmic matter, coming from extra-terrestrial 
 regions, it is on the other hand very probable that 
 cosmic causes, foreign to our globe, may determine 
 on our globe the production of auroras. We have 
 dwelt at some length on the relations which exist 
 between the sun spots on the one hand, and magnetic 
 disturbance, telluric currents, and the aurora borealis 
 on the other, and we have seen that these phenomena 
 
THEOEIES OF THE POLAR AUROEA. 151 
 
 appear to obey the successive phases of solar activity. 
 We shall see that the electric theory of the aurora 
 accounts for these relations. But it is of interest 
 to remark here that the same causes appear to act upon 
 other, planets. The dark hemisphere of Venus has 
 several times appeared to be illuminated, and Win- 
 necke attributes to these faint illuminations a greyish 
 violet tinge. This illumination has been observed in 
 the years 1721, 1726, 1759, 1796, 1806, 1825, 18o5 
 and 1871 ; now some of these years, notably 1726, 
 1759, 1865, and especially 1871, were years of great 
 auroras on the earth. If later observation confirms 
 this correspondence in the two phenomena we shall 
 have the right to regard the lights which are pro- 
 duced on the planet Venus as true polar auroras, and 
 a new argument will be added to all those which tend 
 to show that the physical constitution of that planet 
 resembles that of the earth. 
 
 2. Optical theories. — The optical theories of the 
 aurora are found in germ, in a passage which we have 
 quoted from the * King's Mirror,' a work written in 
 Norway towards the middle of the thirteenth century : 
 * Some persons think that this light (the aurora) is a 
 reflection of the fires which surround the seas to the 
 north and to the south ; others say that it is the reflec- 
 tion of the sun when it is below the horizon ; for my 
 part I think that it is produced by the ice, which 
 radiates by night the light which it has absorbed 
 during the day.' 
 
152 THE POLAR AUEOEA. 
 
 One of these hypotheses, that which regards the 
 aurora as the light of the sun reflected towards us 
 by particles of ice, is evidently derived from the rela- 
 tions which exist betwen the aurora borealis and 
 certain cirrus and cirro-cumulus clouds. We have 
 already dwelt upon these relations. This hypothesis 
 has been maintained by a great number of authors, 
 among whom are Descartes, Ellis, Frobesius, Hell, 
 and in more modern times Sir John Franklin, Eoss, 
 Easpail, and lastly, in 1873, Wolfert. It is clear, 
 however, that this theory encounters capital ob- 
 jections ; it attributes to the upper regions of the 
 atmosphere a power of reflecting light out of all 
 proportion with that which is revealed by the 
 phenomena of twilight. Nor can the auroras be 
 attributed to the reflection of the light of the sun from 
 the particles of ice which compose the cirrus clouds, 
 for we have seen that in the Arctic regions auroras are 
 often produced at but little distance from the surface 
 of the earth, a few miles or even less ; now it is very 
 certain that in these regions, in winter, particles of 
 ice cannot, at so low an elevation, be reached by the 
 rays of the sun. A simple calculation shows that at 
 the time of the winter solstice a point situated only in 
 latitude 70° must, in order to receive the rays of the 
 sun at mid-day, be at more than eleven kilometres 
 above the surface of the earth (seven miles) ; at mid- 
 night it must be as much as 2,400 kilometres (1,490 
 miles). At the equinoxes, in order to be able to 
 
THEOKIES OF THE POLAR AUEOEA. 153 
 
 perceive in lat. 45°, and at midnight, the reflection of 
 the sun's rays from particles of ice, these would have to 
 be at a height of 2,600 kilometres (1,615 miles), which 
 is manifestly impossible. Even admitting a series of 
 successive reflections, the altitude would still be far 
 too great, and it would be hard to understand how 
 after all these reflections the light would have 
 sufficient intensity. Finally, this theory offers no 
 explanation of the incontestable relations which 
 connect the production of the auroras with magnetic 
 disturbances and telluric currents. We may add 
 that the complete absence of polarisation of the light 
 of the aurora borealis is a direct proof that this light 
 has suffered no reflection. Lastly, if the light of the 
 aurora were derived by reflection from that of the 
 sun its spectrum would be continuous and marked by 
 black lines, identical with the solar spectrum, or very 
 similar to it. Now we have seen that the spectrum 
 of the aurora is very different. • The absence of 
 polarisation and the spectrum of the aurora are two 
 characters which alone suffice to destroy absolutely 
 the theory of reflection. 
 
 Another explanation indicated vaguely in the last 
 phrase of the passage from the ' King's Mirror,' which 
 we quoted above, attributes the auroral lights to a sort 
 of phosphorescence. This simple statement is insuf- 
 ficient, for it would be necessary to show what is this 
 substance which possesses, so extraordinary a phos- 
 phorescence, and which has not been found in ice ; 
 
154 THE POLAR AUEOEA. 
 
 and then it would be necessary to show how, under 
 this hypothesis, the periodicity of the auroras, their 
 relation with terrestrial magnetism, &c., could be 
 accounted for. This hypothesis must therefore be 
 abandoned like the preceding ones. 
 
 Yet it is possible that phosphorescence or rather 
 fluorescence may play a certain part in the polar 
 aurora, not as cause but as effect. 'We have said 
 that the light of the aurora is characterised by a 
 certain line in the spectrum of a greenish-yellow colour ; 
 its nature is unknown, but numerous spectroscopists, 
 especially Angstroem and Eand Capron, believe it to 
 be produced by a phenomenon of phosphorescence or 
 fluorescence. This phenomenon in any case is only 
 accessory, and is due to a particular condition of the 
 passage through the air of the electric discharges 
 which constitute the polar aurora. 
 
 3. Magnetic theories. — The theory known as mag- 
 netic, of the aurora borealis, is far more satisfactory 
 than any of the preceding ; it accounts better for the 
 greater number of the phenomena, and has still a 
 number of adherents, though it seems to us that it 
 must yield to the electric theory. 
 
 The magnetic theory dates at least from the 
 famous astronomer Halley, who supposed (1716) that 
 the aurora borealis was due to a ' magnetic vapour,' 
 luminous per se. Independently of vagueness in 
 statement, this hypothesis was not at first received 
 with favour, because at that epoch electro-magnetism 
 
THEORIES OE THE POLAR AURORA. 155 
 
 was still unknown, and experiments of the light- 
 producing power of magnetic action had never been 
 seen. The theory only took definite shape with 
 Dalton (1793). After having collected and published 
 a great number of observations of the aurora borealis, 
 Dalton again showed the relations which existed 
 between the aurora and terrestrial magnetism, 
 discussed the different hypotheses on the nature of 
 the aurora, and finally propounded the theory that 
 the rays of the aurora are composed of ferruginous 
 matter, magnetic in themselves, or else magnetised 
 by the action of the earth. This dust, which takes 
 its direction under the influence of terrestrial 
 magnetism, with its north pole below (in the northern 
 hemisphere) serves as a conductor to silent electric 
 discharges between the upper strata of the atmo- 
 sphere and the lower strata. Dalton concluded that it 
 is not terrestrial magnetism which produces the 
 auroras, but the latter which modify terrestrial 
 magnetism and cause the perturbations. 
 
 Dalton's ideas were revived by Biot (1820), who 
 thought that the aurora boreahs might also be 
 produced by the presence in the air of ferruginous 
 particles by volcanic eruptions. Von Baumhauer 
 (Utrecht, 1840) also supported the same opinions, 
 but attributed the ferruginous particles not to 
 volcanic eruptions of terrestrial origin, but to the 
 fall upon our globe of cosmic, dust ; the light of the 
 aurora would on this theory be produced by the 
 
156 THE POLAR AUEOEA. 
 
 incandescence of this dust when it entered the atmo- 
 sphere, as in the case of meteors and falling stars. 
 Among the most recent defenders of this theory, more 
 or less modified, we may mention Denison Olmsted 
 (1856), Foerster (1870), Zehfuss (1871), Toeppler 
 (1872), and lastly Gronemann (1875). 
 
 Among the arguments urged in favour of the 
 magnetic theory is the existence on the soil of the 
 Arctic regions of great quantities of ferruginous dust, 
 and even of masses of meteoric iron. A rain of dust 
 upon the earth has also been observed during several 
 auroras, notably at Padua in 1834, and throughout 
 northern Italy at the time of the great aurora of 1872. 
 In mentioning these coincidences Toeppler also 
 remarks that the presence round the moon of halos,; 
 which as we have said sometimes occur during an 
 aurora, may likewise be attributed to this meteoric 
 dust. In supposing a cosmic, not a terrestrial, origin 
 to this magnetic dust, the magnetic theory of the 
 aurora is thus nearly identical with that of Mairan, 
 since many authorities believe the zodiacial light to 
 be formed of this cosmic dust. 
 
 As a further proof in support of this magnetic 
 theory it is also alleged that the lines in the spectrum 
 of the aurora are somewhat near to some of those in 
 the spectrum of iron. It is clear, too, that this 
 hypothesis lends itself, in appearance at least, to the- 
 explanation of the relfitions which exist between 
 auroras and terrestrial magnetism. 
 
THEOEIES OF THE POLAR AUEOEA. 157 
 
 On the other hand, the magnetic theories encounter 
 many objections. The last argument, drawn from 
 the analogy of the lines in the spectrum of the aurora 
 with those of iron, is far from being decisive ; the lines 
 of the auroral spectrum are only near a very small 
 number of those of iron, and the brightest lines of 
 this metal are not found in the spectrum of the 
 aurora. Most spectroscopists therefore think that 
 the spectrum of the aurora cannot be attributed to 
 iron, and that the former shows more affinity with 
 the spectrum of electric sparks in very rarefied air. 
 
 If an origin external to the earth is attributed to 
 the ferruginous particles, which, according to the 
 magnetic theory, constitute the aurora, we are con- 
 fronted by the objections which we set forth previously 
 when we dealt with the cosmic theories of the aurora. 
 Moreover, on the hypothesis of dust from the inter- 
 planetary spaces, it is hard to understand why the 
 aurora should never manifest itself in the equatorial 
 region, nor why its frequency should diminish rapidly 
 within the maximum zone, towards the north pole. 
 If, on the other hand, we return to the hypothesis of 
 a purely terrestrial and volcanic origin for this dust, 
 the cause of the diurnal and annual periods of the 
 auroras remains obscure, and also of the difference 
 in this respect between the regions which are within, 
 and those which are without the zone of maximum 
 frequency. 
 
 With regard to the rain of dust which has once or 
 
158 THE POLAK AUEOEA. 
 
 twice been observed in Europe during an aurora, it 
 can only be regarded as a cbance coincidence. No 
 similar rain has yet been observed during an aurora 
 by observers in high latitudes ; now it is especially in 
 those regions, where the aurora is seen almost every 
 night and is much nearer the earth, that frequent 
 falls of ferruginous dust would be observed, v/ere there 
 any relation between them and the production of 
 auroras. 
 
 Finally, it appears to us very difficult to admit 
 that dust, even supposing it to be formed of pure iron, 
 could exercise on the compass needle an influence 
 capable of producing a deviation of several degrees, 
 while it forms at the same time clouds so' transparent 
 as to allow stars of the fourth magnitude to be seen 
 through it. 
 
 All these reasons taken together lead us to reject 
 the magnetic theory as we have already rejected the 
 preceding theories. 
 
 4. Electric theories. — We now reach the electric 
 theories, which are those in which we should seek for 
 the true explanation of the aurora borealis. The first 
 to refer the aurora borealis to a purely electric 
 phenomenon appears to have been the physician 
 Canton ; ' he pointed out in 1753 the close analogy 
 which auroras offer with the light of electric discharges 
 produced in very rarefied air. In his view the aurora 
 
 ' Canton was the first to discover and study the phenomena of 
 Influence; he recognised also that a tube containing rarefied air 
 becomes luminous when moved about near a charged conducting 
 body. 
 
THEORIES OF THE POLAE AUEOEA. 159 
 
 was but the form whicii storms take in polar 
 regions. 
 
 These ideas were adopted successively by Priestley, 
 Eberhard, Frisi, Pontoppidan, Benjamin Franklin, 
 &c., but without making much progress. A very 
 similar opinion was advocated by Fisher in 1834 ; his 
 theory was that auroras are a phenomenon of electric 
 discharge due to the positive electrisation of the 
 atmosphere ; they are produced at the moment when 
 the electric equilibrium is re-established between the 
 atmosphere and the earth, by the intermediary of 
 particles of ice, which are imperfect conductors 
 floating in the air, and serve to bring down to earth 
 the electricity of the upper regions of the atmosphere. 
 In the equatorial regions these particles of ice do not 
 exist sufficiently near the earth ; electric equilibrium 
 can there only be re-established by storms. 
 
 Dove assigns to the auroras of mean latitudes 
 their true origin, supposing them to be produced by 
 magnetic disturbances of the interior of the earth ; 
 for, he says, that which can put the needle in move- 
 ment over a wide extent of territory may also produce 
 brilliant projections of light when the magnetic 
 disturbance of the earth 'reaches its extreme degree. 
 This explanation is the more remarkable that it 
 preceded the discovery made in 1831 by Faraday of 
 the currents of induction produced by the displacement 
 or the variations of magnets. 
 
 Then followed the studies of A. de la Eive, which 
 for a moment were believed to supply a complete 
 
160 THE POLAE AUEOEA. 
 
 explanation of the phenomenon. He supposed that 
 auroras were produced by the positive electricity 
 which, in the upper regions of the atmosphere, is 
 transported by the trade winds from the equator 
 towards the poles. Arrived at the polar regions, this 
 electricity accumulates and attracts below it the 
 negative electricity of the earth. There would thus be 
 a species of condensation, and from time to time dis- 
 charges in the form of auroras, when the tension of 
 the two electricities attained to sufficient values. De 
 la Eive conceived in 1862 an apparatus which would 
 produce luminous appearances analogous to those of 
 the aurora. In this apparatus, which is described in 
 most treatises on physics, a bar of soft iron which 
 rests at one end on a powerful electro-magnet is en- 
 closed in an electric case in which the air can be much 
 rarefied ; the bar is surrounded, except at the two 
 ends, with an envelope of glass, and the spark of a 
 powerful Euhmkorff's coil is passed between the 
 summit and the base of the bar. In these conditions 
 a beam of light is obtained between these two points 
 which plays round the bar of iron, and recalls in form 
 and colour certain aspects of the auroras with rays. 
 We do not insist on this experiment, since it requires 
 conditions which evidently do not obtain in the 
 atmosphere ; a true explanation of the phenomenon 
 cannot therefore be found in it. The same holds 
 good of the beautiful appearances, also resembling 
 auroras, which Gaston Plante obtained with his 
 
THEORIES OF THE POLAR AURORA. 161 
 
 « 
 
 powerful secondary battery, when the negative elec- 
 trode is plunged into a vessel filled with brine, and the 
 positive electrode is brought close to the damp walls 
 of the same vessel. 
 
 Lemstroem ^ invented another experiment which 
 gives results much nearer to the aurora borealis both 
 in general appearance and probably also in mode of 
 production,' An insulated metallic ball, armed with 
 a few points, communicates with one of the poles of 
 a Holtz machine, of which the other pole is connected 
 with the earth. At a certain distance from this ball, 
 and opposite to one of the points, are placed some 
 Geissler tubes, of which the further ends are also 
 placed on the ground, while those nearer to the ball 
 are insulated. As soon as the Holtz machine is set 
 in motion the Geissler tubes are illuminated ; under 
 favourable circumstances and with a good electric 
 machine this illumination takes place when the tubes 
 are as much as two yards away from the ball. The 
 passage of the electricity, which is not shown by any 
 light between the ball and the tubes, that is in air at 
 the ordinary .pressure, is thus quite sufficient to light 
 up the very rarefied air contained in the Geissler 
 tubes. Of all the experiments hitherto attempted in 
 the way of reproducing artificially the effects of the 
 aurora borealis, this is certainly the one which most 
 nearly approaches the natural phenomenon. 
 
 Another theory, more complete than any of the 
 
 ' Archives des Sciences physiques et naturelles, 1875, vol. liv. 
 12 
 
1G2 THE POLAR AUEOEA. 
 
 preceding, was proposed a few years ago by Edlund.' 
 We shall give it at some length, in spite of some 
 objections which have been pointed out from the 
 point of view of physics, because this theory, with some 
 modification's and additions, seems to us to explain in 
 the most satisfactory manner the different properties 
 oi the aurora borealis. 
 
 Edlund takes as his point of departure the 
 phenomena known as unipolar induction, which 
 were discovered by W. Weber, and which he himself 
 has studied very thoroughly. This is the name given 
 to those currents which arise in each half of a metallic 
 sheath which surrounds a magnet when the sheath 
 is rapidly revolved round the magnet. To show the 
 production of these currents it is enough to apply 
 two metal springs to the revolving sheath ; the one 
 should be placed opposite one of the poles, the other 
 opposite the neutral line of the magnet ; then these 
 two springs must be connected by a circuit containing 
 a galvanometer. The currents are produced in the 
 same way, whether the magnet remains motionless or 
 is dragged along in the same movement of rotation as 
 the sheath which surrounds it. 
 
 It is known that the general phenomena of mag- 
 netism can be explained on the hypothesis that the 
 earth contains a magnet with two poles. The earth, 
 being a relatively good conductor of electricity and 
 
 ' B. Edlund, ' Eecherches sur I'lnduotion Unipolaire, l'Eleotrioit6 
 AtmosphSrique et I'Aurore Bor^ale ' {Actes de I'Acadimie des Sciences 
 de Suide, vol. xvi., Stockholm, 1878). 
 
THEORIES OF THE POLAR AURORA. 163 
 
 animated by a movement of rotation, is thus similar 
 to the sheath of which we spoke above, and conse- 
 quently the phenomena of unipolar induction should 
 be produced in it. 
 
 We will suppose, to simplify the question, that 
 the axis of the terrestrial magnet coincides with the 
 axis of the earth's rotation, or, in other words, that 
 the magnetic poles do not differ from the geographical 
 poles. We know that this is not so, but we shall 
 see later what modifications this actual difference 
 produces in the facts. In calculating first on this 
 simple hypothesis all the circumstances of unipolar 
 induction, Edlund shows that a molecule charged with 
 positive electricity, taken on the surface of the earth, 
 is subjected to two forces — the one vertical, from below 
 upwards, which tends to drive this molecule upwards 
 into the air, following the direction of the radius of 
 the earth ; the other perpendicular to the first, directed 
 along the meridian and, in each hemisphere, tending 
 to draw the molecule towards the nearest pole. The 
 first force is at its maximum at the equator and nil 
 at the poles ; the other, on the contrary, is nil at the 
 equator and increases with the latitude,- then diminishes 
 and becomes nil again at the poles. The resultant of 
 these forces is at each point of the earth situated in 
 the meridian, and perpendicular to the direction of 
 the magnetic dipping needle. 
 
 Under the influence of these forces the electrified 
 molecules leave the surface of the earth to rise in the 
 
1G4 THE POLAE AUEOEA. 
 
 atmosphere, and this effect is produced especially in 
 the equatorial regions where the force is greatest. 
 Electricity is thus accumulated in the higher regions 
 of the atmosphere, and this is in agreement with the 
 observed fact that the electric potential increases with 
 the altitude. Now it is known, and other works of 
 Edlund have contributed to the sum of knowledge on 
 the subject, that very rarefied gases are good con- 
 ductors of electricity ; the fancied resistance of a 
 vacuum is due to the difficulty which electricity experi- 
 ences in leaving the electrode, not in traversing the 
 surrounding medium. When it has reached a suffi- 
 cient height in the atmosphere, the electricity will find 
 strata which offer little resistance, and consequently it 
 will be able to obey without difficulty the forces which 
 attract it towards the polar regions. 
 
 In order to descend to the earth again this 
 electricity has two courses open to it : either disrup- 
 tive discharges through the air, — the storms of the 
 equatorial and mean latitudes ; or slow discharges in 
 the form of continuous currents which are produced 
 in high latitudes ; these are the polar auroras. These 
 continuous currents might be produced at the pole 
 itself, since at that point the vertical force is nil ; 
 but as a general rule the electricity of the atmosphere 
 will re-enter the earth long before it reaches the 
 pole, provided that it follows the direction of the 
 magnetic dipping needle, because, as we have seen 
 above, the resultant of the forces which act on the 
 
THEOEIES OF THE POLAE AUEOEA. 165 
 
 electrified molecules is perpendicular to tliis direction. 
 In order to flow towards the earth, following this 
 direction, in a given latitude, the electricity has only 
 to overcome the resistance of the air. Now the 
 quantity of electricity accumulated in the atmosphere, 
 and consequently its tension, increases with the 
 latitude ; at a given moment then, the tension 
 having become very great, the electricity of the 
 upper regions of the atmosphere will flow downwards 
 towards the earth in currents which follow the 
 direction of the magnetic dipping needle; this flow 
 will occur by preference in regions where, as a conse- 
 quence of particular meteorological conditions, tem- 
 perature, humidity, &c., the conductivity of the air is 
 greatest. On the hypothesis of the symmetry of all 
 the phenomena round the geographical pole, this 
 flow of electricity would be produced in a zone of 
 which the centre would be the pole. 
 
 In reality the poles of the terrestrial magnet do 
 not coincide, as we supposed, with the axis on which 
 the earth rotates. The magnetic pole of the northern 
 hemisphere is in latitude 73°, and in longitude 98° 
 (from Paris) ; but this only complicates the calcula- 
 tion a little, and hardly modifies the general con- 
 clusions. The tangential force, which we found to be 
 nil at the geographical pole, is in reality nil neither 
 at the geographical nor at the magnetic pole, but at a 
 point situated between the two. The annular zone 
 in which the auroras most frequently occur is hot a 
 
166 THE POLAR AUEORA. 
 
 circle of which the centre is the geographical pole, 
 but takes an oval form and cuts the meridian which 
 passes through the magnetic pole at a much lower 
 latitude on the side of the Atlantic than on the 
 opposite side. This shows a remarkable agreement 
 with the results of observation of the form and posi- 
 tion of the zone of the maximum frequency of the 
 aurora borealis. 
 
 Omitting the general phenomena of atmospheric 
 electricity, which are also in agreement with Edlund's 
 theory, and concerning ourselves solely with the 
 aurora borealis, it will be seen that this theory 
 explains satisfactorily : 
 
 1. The direction of the rays of the aurora. 
 
 2. The existence, the form, and position of the 
 zone of maximum frequency. 
 
 3. The deviation of the summit of the arc from 
 the magnetic meridian. For, by allowing for the 
 geographical position, and the magnetic declination of 
 a given locality, and also for the form and situation 
 of the maximum of electric density, the theory of 
 Edlund permits us to calculate the deviation of the 
 summit of the arc from the magnetic meridian. Thus 
 at Bossekop and at Abo this deviation should be 
 about ten degrees to the west, while the summit of 
 the auroral arc should approach the magnetic 
 meridian much more nearly in North America and in 
 Siberia. These results are in perfect agreement with 
 the observed facts (see page 124). 
 
THEORIES OF THE POLAR AURORA. 167 
 
 4. The accidental deviations which may be 
 produced if, as a result of particular meteorological 
 conditions, the resistance of the air becomes much 
 less in a direction different to that of the magnetic 
 needle, along which the flow of electricity should 
 normally proceed. 
 
 5. Finally, it will be seen that if this theory does 
 not explain directly the annual and diurnal variations 
 of the aurora, it at least allows us to foresee that the 
 explanation may be connected with this theory, after 
 a study of the periodic changes in the conductivity 
 of the air resulting from the variations of the different 
 meteorological elements. 
 
 We will conclude our review of the theories to 
 which the aurora borealis has given birth by a sketch 
 of the most recent of them all, that of J. Unterweger.' 
 
 The starting point of this theory is purely hypo- 
 thetical, and is not susceptible of verification ; but 
 the results to which it leads appear to agree with a 
 great number of the observed facts ; it deserves 
 mention, therefore, in spite of its hypothetical 
 character, among the other general theories of the 
 aurora borealis. 
 
 It is known that the sun is not fixed in space, but 
 that it moves with a velocity of about thirty-three 
 miles a second towards a point situated in the con- 
 
 ' J. Unterweger, ' Beitrage zur Erklarung der ooamisch-terrestri- 
 Bohen Erscheinung ; fiber das Polarlioht ' (Denksclwiften der Akdd. 
 der Wissenschaften, vol. 1., Vienna, 1885). 
 
168 THE POLAE AUEOEA. 
 
 stellation of Hercules. All the planets are implicated 
 in this movement, so that the earth, instead of 
 describing a closed ellipse, of which the sun occupies 
 one of the foci, really moves on a sort of elliptical 
 helix traced on a cylinder of which the axis is the 
 path of the sun through space. As the plane of the 
 earth's orbit cuts this axis obliquely, the absolute 
 velocity of the earth through space presents a regular 
 annual variation ; it is greatest towards the middle of 
 March (about forty-four miles a second), and least 
 towards the middle of September (about thirty miles 
 a second). 
 
 On the other hand, in order to explain the propa- 
 gation of heat and light, science has been constrained 
 to suppose the existence of an imponderable but 
 elastic medium, ether, which transmits the vibrations 
 of heat and light. This ether fills all the celestial 
 spaces and also material bodies. 
 
 Starting from these data Unterweger supposes 
 that the cosmic ether, that is to say, that which fills 
 the celestial spaces, when it is met by the earth in its 
 movement, of which we have just indicated the nature, 
 is compressed or condensed in front of the earth in 
 the direction of its movement, and dilated or rarefied, 
 on the contrary, behind it. Thus the cosmic ether 
 in advance of the earth would be more condensed 
 than that which our globe bears along with it, and it 
 would be more rarefied behind. If we admit, moreover, 
 that the condensed ether has a positive electric potential 
 
THEOEIES OF THE POLAR AUEOEA. 169 
 
 with regard to rarefied ether, it results that that half 
 of the earth which presents itself first in its movement 
 through space, and which comprehends the greater 
 part of the northern hemisphere, will be negatively 
 electrified with regard to the regions of space towards 
 which it is directed ; in the same way the half of the 
 earth which is behind, and which comprehends the 
 greater part of the southern hemisphere, will be 
 electrified positively with regard to the regions of 
 space which it is leaving. 
 
 By means of his electrical apparatus Lemstroem 
 has shown (see page 116) that in Lapland the terres- 
 trial current at a certain distance from the earth is 
 directed from above downwards, from the upper 
 regions towards the earth ; this fact, on the interpre- 
 tation of which we made certain criticisms, appears 
 to agree with Unterweger's hypothesis. But this 
 same hypothesis indicates that the terrestrial current 
 should show a different direction in the southern 
 hemisphere; experiments similar to those of Lem- 
 stroem repeated in high austral latitudes, at Cape 
 Horn or on Kerguelen Island, for instance, are of 
 capital importance for the confirmation of this theory. 
 
 From calculations based on the rapidity of the move- 
 ment of the earth, and of the inclination of the axis to 
 the plane of the orbit, Unterweger finds that the electri- 
 sation of the northern hemisphere should be at its 
 maximum in September, and at its minimum in March. 
 The sum of the days of aurora and of the days of storm 
 
170 THE POLAR ATJEOEA. 
 
 in many parts of our hemisphere presents this same 
 annual variation, maximum in October, minimum in 
 March, and this appears to Unterweger to be a first 
 confirmation of his theory. It must be remarked that 
 the auroras taken alone and independently of storms 
 do not follow the same law, and that their frequency 
 has each year, at least in most countries, two maxima 
 — in spring and autumn. 
 
 Unterweger explains the diurnal variation of the 
 aurora (p. 80) by adding to his original hypothesis 
 a second, viz. that the sun has a positive electrical 
 potential with regard to the earth. The action of the 
 sun thus modifies the distribution of electricity in the 
 higher regions of the atmosphere. In calculating this 
 action, it is shown that instead of being distributed 
 equally over all parts of a zone of the same latitude, 
 the electricity leaves in part that portion of the zone 
 which is turned towards the sun for that which is in 
 shadow ; in this latter portion the electricity is not 
 distributed uniformly, but is found especially towards 
 the west. The result is that auroras should be more 
 frequent during the first hours of the night, and that 
 over the whole earth, and this law is confirmed by 
 observation. 
 
 The same reasons explain also the displacement of 
 latitude presented in the course of the year by the 
 zone of maximum frequency. We have just seen that 
 under the repelling action of solar electricity the elec- 
 tricity of the upper strata of the atmosphere accumu- 
 
THEOBIES OF THE POLAE AURORA. 171 
 
 lates especially on the side opposed to the sun, in that 
 portion which is in shadow. Now the region of shadow 
 has the widest surface at the equator, and narrows 
 with the increase of latitude ; the tension of the elec- 
 tricity spread over this region increases in proportion 
 as the surface over which it can spread itself dimi- 
 nishes, and is at its maximum near the summit of the 
 region of shadow. In calculating the position of this 
 summit at each season, Unterweger finds that the maxi- 
 mum of electrisation, and consequently the maximum 
 of auroras, is situated in latitude 88° at the winter 
 solstice, in latitude 55° at the summer solstice, and in 
 latitude 78° at the equinoxes. 
 
 The relation of the aurora with the solar spots is 
 explained by the supposition that the appearance of 
 the spots coincides with a variation of the electrical 
 potential of the sun. Finally, the relation of the 
 aurora with terrestrial magnetism is as easy to under- 
 stand on this theory as on any other electrical theory. 
 
 In conclusion, the hypotheses of Unterweger ap- 
 pear to explain better than Edlund's theory the annual 
 variation, and especially the diurnal variation of the 
 aurora ; but on the other hand they render account 
 with much less ease of a number of important phe- 
 nomena, such as the direction of the arcs and of the 
 rays, the oval form of the zone of maximum frequency, 
 the deviation of the arc from the magnetic meridian, &c. 
 
 If Edlund's theory is not established at all points, 
 nor free from objections on physical grounds, that of 
 
172 THE POLAE AUEOEA. 
 
 Unterweger rests on no experimental basis; it is a 
 tissue of hypotheses — admissible, no doubt — but of 
 which none is proved, and probably never will be 
 proved. To be preferred to that of Edlund, it should 
 explain better than it does a greater number of the 
 phenomena, which is not the case — at least, until 
 Unterweger's theory has been further elaborated. 
 
 It seems to us, therefore, that of all the theories 
 which we have set forth the most satisfactory in its 
 general features is that of Edlund. It is that which 
 should be retained, at any rate, for the present, and 
 in its main features, and with certain restrictions. 
 For this theory, which explains in a very simple man- 
 ner the characters proper to the auroras of the polar 
 regions, is less satisfactory with regard to the auroras 
 of immense extent which are seen simultaneously in 
 the two hemispheres over more than two-thirds of the 
 surface of the globe. It is not clear why, on this 
 theory, there should be a coincidence between the two 
 hemispheres. It is well to recall in this connection 
 what we have already said more than once, that it 
 seems to us that the name of aurora is given in com- 
 mon to two very different phenomena. 
 
 According to this view the ordinary aurora of the 
 polar regions, those, for example, which were observed 
 80 continuously by the French Commission at Bossekop 
 and by Nordenskioeld during the wintering of the 
 ' Vega,' constitute a first group of phenomena, which 
 seem to us to be almost completely explained by 
 
THEORIES OF THE POLAR AUEOEA. 173 
 
 Edlund's theory. The auroras of this class are in 
 general limited to the polar regions, and are only 
 exceptionally seen in lower latitudes. They are local 
 phenomena, which have a tendency to appear in oval 
 zones, of which, the centre, as indicated in Edlund's 
 theory, lies between the geographical and magnetic 
 poles. These auroras constitute the regular return 
 to the earth of the electricity which in lower latitudes 
 has been driven by unipolar induction into the higher 
 regions of the atmosphere. It is easy to understand 
 that this regular flow, which is moreover of no great 
 intensity, should have no influence on the needle of 
 the compass. These auroras are seen now at one 
 point, and now at another of the auroral zone, at a 
 lower or a higher latitude, according as the conduc- 
 tivity of the air varies with meteorological conditions, 
 temperature, humidity, &c. If there be a stratum of 
 cloud formed of particles of ice, this stratum will form 
 a conductor, and this explains the intimate relations 
 which we have noted between clouds and auroras 
 (chap. iv. para. 2). Finally, the same theory explains 
 the contrast in the variations of the frequency of the 
 auroras presented by mean and polar latitudes (p. 98). 
 For if the electricity of the upper strata of the 
 atmosphere finds in mean latitudes favourable condi- 
 tions for returning to the earth, it will flow downwards 
 before arriving in high latitudes, and the frequency of 
 the aurora, increasing in mean latitudes, will diminish 
 by just so much in polar latitudes, because the elec- 
 
174 THE POLiVE AUEOEA. 
 
 tricity will have disappeared without reaching them. 
 In order to elucidate completely the conditions in 
 which these auroras are produced, it is necessary to 
 discover whether they present any relation with the 
 vertical movements of the atmosphere, whether, for 
 example, their position has any relation with the 
 centres of high and low pressure. But in these re- 
 searches attention should be directed exclusively to 
 these auroras of the first class, eliminating all the 
 auroras of the second class — of which we will treat 
 presently — and which, as they are seen simultaneously 
 in the two hemispheres, or at least over a wide extent 
 of territory, have clearly no connection with meteoro- 
 logical conditions. It would he of capital importance 
 also to organise regular observations of atmospheric 
 electricity, taken at a large number of stations under 
 conditions which should be strictly comparable, so as 
 to study the variations in the electrical potential of 
 the atmosphere according to the latitude, a phenome- 
 non about which we possess at present no data. 
 
 A second class of auroras, . entirely different, in 
 our opinion, from the first, comprehends the very 
 extensive auroras which are produced simultaneously 
 over a vast space, and often, if not always, in both 
 hemispheres. By far the greater number of auroras 
 seen in mean latitudes belong to this class, and they 
 are always accompanied by marked magnetic dis- 
 turbances and telluric currents. In our view, these 
 auroras do not come under Edlund's theory, but should 
 
THEORIES OF THE POLAR AURORA. 175 
 
 be considered as a phenomenon of induction produced 
 by the telluric currents or by magnetic perturbation. 
 We have already indicated, in the chapter on the rela- 
 tions of the aurora with terrestrial magnetism and 
 telluric currents, the principal reasons on which this 
 opinion is based. It seems very natural to admit that 
 any sudden interruption of the magnetic or electrical 
 equilibrium of the globe should be accompanied by 
 corresponding electrical movements in the electrified 
 strata which form the upper regions of the atmosphere. 
 Laboratory experiments with Geissler's tubes show 
 us, moreover, that these tubes grow suddenly luminous 
 whenever the electric field in which they are placed 
 changes abruptly. Auroras of the second class are, 
 on this theory, but the reflection in the upper regions 
 of the atmosphere of modifications of the magnetic 
 state of the earth; instead of producing these per- 
 turbations, they are, on the contrary, produced by 
 them. Moreover, they would always have their seat 
 at a great altitude, there where the air has a degree 
 of rarefaction comparable to that of Geissler's tubes, 
 that is to say, at a height of thirty or forty miles ; 
 whereas the auroras of the first class may occur much 
 lower, and even quite close to the surface of the earth ; 
 this also accords with the results of observation. 
 
 Magnetic disturbance and telluric currents having 
 a known relation with the spots on the sun, it becomes 
 clear that it will be the same with auroras of the second 
 class, without the need of seeking a direct relation 
 
176 THE POLA^ AUEOEA. 
 
 between this last phenomenon and the spots on the 
 sun. 
 
 In conclusion, the considerations which we have 
 just set forth account satisfactorily for the principal 
 phenomena of the aurora borealis ; and with regard 
 to those which they do not directly explain, such as 
 the diurnal and annual variation, they indicate the 
 direction in which the explanation should be sought. 
 
 Among the capital points in regard to which there 
 is still considerable uncertainty we may mention 
 especially the spectroscopic study of the light of the 
 aurora. Doubtless it may he regarded as more than 
 probable that auroras are produced by electrical dis- 
 charges in very rarefied air ; but laboratory study of 
 the spectra of the electric spark in gases has not 
 hitherto been able to discover all the lines of the 
 aurora, and notably the principal one, that which is 
 most characteristic of the phenomenon. These studies 
 should be renewed, the conditions of the experiment 
 being varied as much as possible. Whenever the 
 spectrum of the aurora boreaHs is artificially repro- 
 duced, not only one of the remaining obscure features 
 in this phenomenon will be elucidated, but we shall 
 obtain at the same time most valuable information as 
 to the composition and properties of the upper regions 
 of the air. 
 
APPENDIX. 
 
 CATALOGUE OF THE AURORAS SEEN IN EUROPE 
 BELOW LAT. 55° FROM 1700 TO 1890. 
 
 This catalogue is taken, as far as the year 1872, from the 
 general catalogue published by Hermann Fritz, ^ which is a 
 summary of all previous catalogues. We have confined ourselves 
 to the appearances of the aurora boreaUs in Europe, and below 
 the 55th degree of latitude. Beyond this limit, especially 
 towards the north of Norway, the aurora is so frequent that, 
 during certain periods, it may be seen every day ; it is then, as 
 a rule, a purely local phenomenon. 
 
 Hermann Fritz's catalogue ends in the early months of 1872 ; 
 we have prolonged it to the end of 1890, using the official pub- 
 lications of the meteorological observatories of the following 
 countries: Spain, Italy, Prance, England, Holland, Belgium, 
 Germany, Bavaria, Saxony, Austria, Hungary, Eussia. We have 
 also searched the weekly or monthly periodicals which are 
 devoted, partially or entirely, to meteorology. 
 
 Fritz gave, in his catalogue, a brief indication of the source 
 of each observation. We have omitted this, for the sake of 
 brevity ; it may be found in the original when required. 
 
 It is probable that, with every care, this catalogue is still 
 incomplete. Many faint auroras altogether escape observation. 
 It is especially after fine auroras, when attention has been 
 directed to this phenomenon, that observers note faint auroral 
 lights, of which the recorded number is at first very great, and 
 then dwindles rapidly as observation tires. The continual 
 increase of street lighting in towns is another cause of the failure 
 to notice the fainter manifestations of the aurora. Besides 
 these sources of error it may be that some few auroras which 
 have reaUy been observed are omitted in this catalogue. We 
 shall be grateful to any one who will supply the omissions. 
 
 ' Verzeichniss heobachteter Polarlichter, Wien, 1873. 
 13 
 
178 THE POLAE AUEOEA. 
 
 In the following catalogue we indicate, after each date, the 
 localities where an aurora borealis has been noticed. Where 
 the name of a country is given instead of that of a town, it 
 signifies that an aurora has really been observed in that country 
 but without precise indication of the place or places. A query 
 after a date, without other indication, signifies that the author 
 responsible for the information has mentioned an aurora borealis 
 under that date, but without naming the country where the 
 observation was made. The query after the name of a country 
 indicates that the observation is doubtful, the phenomenon 
 being undefined. Finally, when an aurora borealis was observed 
 at the same date in different localities, we have grouped these 
 localities according to country, and always, as far as possible, 
 in the same order. A comma separates locaUties belonging to 
 the same region; a semicolon those belonging to different 
 countries. 
 
 1704. Nov. 3. Canton of Zurich. 
 
 1705. April 19. Zurich. 
 
 1706. Sept. or Oct. Upminster (England). 
 
 1707. Mar. 1. Berlin, Schoenberg (Altmark, Saxony).— 6th. 
 
 Berlin, Schoenberg, Schneeberg. 
 
 — Aug. 5. Breslau. — 6th. Breslau. 
 
 — Oct. 19. Schoenberg (traces of an aurora). — 20th. 
 
 Schoenberg -(traces of an aurora). — 21st. 
 Berlin, Schoenberg. — 26th. Schoenberg. — 
 29th. Berlin. 
 
 — Nov. 6. Berhn ; Ireland.— 27th. (?) Upminster. 
 
 1708. Aug. 9. Hereford.— 10th. Hereford.— 20th. London. 
 
 — Sept. 11. Jena, Halle, Leipzig, Naumburg. 
 
 1709. Oct. 18. Durham.— (?) (towards the end of the month.) 
 
 Hoi stein. 
 
 1710. Nov. 26. Giessen, Leipzig. 
 
 1715. Mar. 17. Elbing and district (western Prussia). 
 
 1716. Mar. 15. London (very brilliant aurora) ; Ukraine. — 
 
 16th. Utrecht ; Brandenburg, Dantzig. — 
 17th. A very widely extended aurora, visible 
 throughout Spain, Portugal, Italy, France, 
 England, Switzerland, the Low Countries, 
 Austria, Hungary, Germany, Sweden, Bussia, 
 North America. — 24th. Switzerland ; London, 
 Windsor. 
 
 — April 10. Wittenberg (Saxony). — 11th. Paris, Valincour, 
 
 Dieppe ; London, Dublin. — 12th. Paris ; Lon- 
 don, Dublin, Cotterstock ; Dantzig. — 20th, 
 21st, 22nd, 23rd, 24th. Dantzig. 
 
 — Nov. 16. Neuchatel (Svritzerland). 
 
APPENDIX. 179 
 
 1716. Dec. 15. Paris.— 16th. Paris. 
 
 1717. Jan. 6. 9, 10, 11. Paris. 
 
 — Feb. 2. Berlin.— 16th. Sutton-at-Hone (England). 
 
 — Mar. 30. Eoohester. 
 
 — April 10. London, Sutton-at-Hone ; Wittenberg, Berlin. 
 
 — Aug. 10. Hungary, Silesia ; Poland ; Prussia. — 25th, 
 
 26th, 27th. Milan.— 31st. Berlm. 
 
 — Sept. 8, 20. Berlin. 
 
 — ■ Oct. 15. Paris, Berlin. 
 
 1718. Jan. 25. Silesia, Massel. 
 
 — Feb. 21. Keichstadt ; Bohemia ; Silesia ; County of 
 
 Hereford. 
 
 — Mar. 4. Paris ; Berlin, Breslau.— 10th. Zurich— 19th. 
 
 Berlin. — 22nd. Bohemia. 
 
 — May 1. Berlin. 
 
 — Sept. 16. Paris; Lynn Begis; Berhn. — 17th, 22nd, 
 
 24th. Lynn Eegis. 
 
 — Oct. 22. Keichstadt; Bohemia. — 23rd. Paris. 
 
 — Nov. 23. Paris; Brandenburg. — 25th. Berlin. 
 
 — Dec. 6. Berlin, Glogau, Breslau, Eisenberg. — 18th. 
 
 Paris.— 20th. Germany.— 30th. Berlin ; 
 Mecklenburg ; Hanover ; Hadeln ; Lynn 
 Begis. 
 
 1719. Feb. 11. Berlin.— 12th, 13th. Massel. 
 
 — Mar. 23. South of France ;' Norfolk.- 24th. (?) Mont- 
 
 aaban (perhaps a confusion with the aurora 
 of the 23rd.).— 30th. Paris; Neuchatel 
 (Switzerland) ; London ; France ; Belgium ; 
 England. 
 
 — AprU 7. Paris; Norfolk.— 17th. Paris. 
 
 — Sept. 22, 24. England. — 25th. Lithuania. 
 
 — Oct. 16. Berlin, Beichstadt, Magdeburg. — 18th. Reich- 
 
 stadt.— 22nd. England.— 23rd. Halle. 
 
 — Nov, 3. Breda ; Beichstadt. — 6th. Massel, Lausitz, 
 
 Breda ; Norfolk, Gruwys-Morchard. — 8th. 
 Berlin. — 11th. Magdeburg. — 13th. Berlin, 
 Beichstadt ; the whole of Saxony ; Holland. 
 —14th. Nordhausen.— 16th. (?) —19th. (?) 
 — ^20th. Berhn, Lausitz, Magdeburg;, Lon- 
 don, Norfolk, Cruwys - Morchard. — 21st. 
 Wittenberg ; Utrechli, Breda ; London, 
 Streatham, Dublin, Cruwys-Morchard. — 
 28th. Luzm. 
 
 — Deo. 5. Breda ; Dublui. — 7th. England. — 18th. Guhr. 
 
 —22nd. The whole of Hungary, Bohemia ; 
 Streatham. — 30th. (?) — (?) Auroras were 
 
180 THE POIAE AUEOEA. 
 
 observed in Paris by Maraldi in November and 
 December ; the precise dates are unknown. 
 
 1720. Jan. 2. Berlin.— 3rd. CEdenburg (Hungary). 
 
 — Feb. 6. Paris, Orleans; Brandenburg. — ^lOth. Paris; 
 
 Brandenburg. — 11th. Paris ; Lynn Eegis ; 
 Luzin. — 12th. Eouen. — 15th. Berlin. — 18th. 
 Paris ; Brandenburg. 
 
 — Mar. 9. Paris.— 11th, 23rd. (?) 
 
 — Apr. 7, 11. (?) 
 
 — Sept. 10. Paris. — 28th. London, Lynn Eegis. 
 
 — Oct. 22. (?)— 27th. Niirenberg. 
 
 — Nov. 6, 7, 20, 25. (?)— 29th. Paris ; Marsel. 
 
 — Deo. 2. Corsica. — 3rd. Upminster. — 6th. Saxony. — 
 
 20th. Paris. 
 
 1721. Jan. 1. (?) — 17th. Paris ; Lynn Begis ; Giessen. — 
 
 22nd. Paris. — 23rd. Lynn Eegis. 
 
 — Feb. 11. (?)— 17th. Paris, Saint Malo, Eiom ; Cruwys- 
 
 Morchard ; Switzerland ; throughout Ger- 
 many. — 18th. Warsaw. — 22nd. Paris. — 
 23rd. Paris ; Nuremberg ; Hungary. — 26th. 
 Lehotta ; Paris. — 28th. Augersburg, Dantzig. 
 
 — Mar. 1. Paris, Eennes, Saint Malo; Nimeguen; Zurich; 
 
 throughout Germany ; Warsaw. — 9th. 
 Cracow. — 18th. Stuttgart. 
 
 — May 28. Berlin. 
 
 — Aug. 15. Paris. 
 
 — Sept. 16. Giessen. — 22nd. Paris ; Lynn Eegis ; Nurem- 
 
 berg ; Weimar ; Magdeburg. — 28th. (?) 
 
 — Oct. 12. Luzin ; Dresden ; Poland. — 13th. Luzin ; 
 
 Dresden, Poland. — 20th. Nuremberg. — 21st. 
 Paris ; Magdeburg. 
 
 — Nov. 12. Dresden. — 13th. Luzin. — 28th. Warsaw. 
 
 1722. Jan. 7. Paris. — 8th. Paris. — 9th. Paris. — 11th. 
 
 Nuremberg. — 12th. Paris ; Nuremberg. — 
 14th. Nuremberg, Breslau.— 17th. (?)— 
 23rd. (?)— 31st. Berlin. 
 
 — Feb. 12. Seehausen, near Magdeburg. — 13th, 16th, 
 
 Seehausen. — 20th. Paris. 
 
 — Mar. 1. Dantzig ; Koenigsberg. — 6th. Kcenigsberg, 
 
 Augersburg. — 7th. Nuremberg ; Breslan. 
 — 9th. (?)— 16th. Nuremberg. — 24th, 
 Limbach, near Dresden. — 27th. Berlin. — 
 29th. (?) 
 
 — May 12. Lcebau.— 24th. Janer (Silesia). 
 
 — Sept. 5. Paris; Oschatz (Saxony). — 6th. Paris; Oschatz, 
 
 Striegau, Naumburg; Seehausen. — 7th. 
 
APPENDIX. 181 
 
 Seehausen. — 10th. Paris.— 12th. (?)— 16th. 
 Paris, London, Lynn Begis. — 17th. Berhn. 
 —18th. Berlin.— 22nd. (?) 
 
 1722. Oct. 3. Limbach, Seehausen; Berlin. — 7th. Berlin. 
 
 —8th, 9th, 10th. Seehausen.— 14th. Paris; 
 Lynn Eegia ; Seehausen. — 15th. Lynn ' 
 Eegis; Seehausen. 
 
 — Nov. 3. Seehausen.— 9th. (?)— 11th. Giessen.— 12th, 
 
 13th. Limbach. — 22nd. Dantzig.— 23rd. 
 Loebau. 
 
 — Deo. 1. Limbach. — 4th. Seehausen. — 7th. Berlin. — 
 
 31st. Bologna. 
 
 1723. Jan. 1. Nuremberg. — 3rd. Bologna, Paris, Lynn Begis, 
 
 Seehausen. Twice also during this month 
 auroras were observed at Limbach (near 
 Dresden), but the dates are not given. 
 
 Paris. — :27th. Giessen. 
 
 Lynn Begis. — 3rd. Berlin. — 10th. Breslau. — 
 25th. Paris. — 26th. Lynn Eegis. 
 
 Paris, Berlin. 
 
 Jauer (?). — 31st. Lynn Begis. 
 
 Jauer. — 17th. Jauer. 
 
 Lynn Begis, Lajbau, Lausitz, Saxony. 
 
 Paris, Saxony. — 5th. (?). 
 
 Paris. — 7th. Jauer. 
 
 1724. Jan. 17. Nuremberg. — 29th. Lemberg, Loebau 30th. 
 
 Central Europe. 
 
 Eawicz (Posen). 
 Jauer. — 22nd. Lcebau. 
 Aug. 4, 12, 17, 24, 31. Central Europe. 
 
 — Sept. 9, 22, 23. Central Europe. 
 
 — Dec. 26. Central Europe. 
 
 Auroras were frequently observed Sit Paris by 
 Maraldi durmg the spring and autumn of 
 1724, at micertain dates ; they were fainter 
 than those of the previous year, and showed 
 a uniform light. 
 
 1725. Jan. 8. Silesia, Lausitz, Seehausen. — 9th. Paris, Silesia, 
 
 Lausitz, Seehausen, Berlin. — 12th. Lcebau, 
 Silesia, Lausitz. — 13th. Loebau, Silesia, Lau- 
 sitz, Berlin. 
 
 — Feb. 12. Berlin. 
 
 — Mar. 16. Berhn. 
 
 — April 24. Berlin. 
 
 — Aug. 22. Berlin (traces of an aurora). 
 
 — Sept. 16. (?) 
 
 Feb. 
 
 4. 
 
 Mar. 
 
 2. 
 
 April 
 Aug. 
 Sept. 
 Oct. 
 
 24. 
 
 27. 
 
 1. 
 
 31. 
 
 Nov. 
 
 1. 
 
 Dec. 
 
 2. 
 
 Jan. 
 
 17. 
 
 Mar. 
 
 24. 
 
 May 
 
 4. 
 
182 THE POLAH AURORA. 
 
 1725 Oct. 2. Seehausen. — 5th. Castle Dobbs (Ireland), Si- 
 lesia, Lausitz, Jauer, Lcebau, Seehausen, 
 Berlin. — 6th. Paris, Castle Dobbs. — 7th. 
 Lynn Eegis, Silesia, Lansitz, Loebau, Bres- 
 lau, Berlin, Bawicz, Poland. — 8th. Silesia, 
 Lausitz, Seehausen. — 9th. Silesia, Lausitz, 
 Loebau.— 14th, 15th. (?) 
 
 — Deo. 4. Dantzig. — 5th, 6th, 7th. Dantzig, Silesia, Lau- 
 
 sitz, Germany. — 12th. (?). — 17th. Ksesmark. 
 —25th (?). 
 
 1726. Jan. 8. (?). 
 
 — Feb. 6. Loebau. 
 
 — Mar. 6. Berlin. — 17th. Coasts of Spain. — 24th. Nurem- 
 
 berg.— 28th. Berhn. 
 
 — April 2. Berlin. — 23rd. Upminster. 
 
 — Sept. 5. Loebau.^-26th. Paris, BreuiUepont (Eure). — 
 
 27th. BreuiUepont. — 28th. Jauer. 
 
 — Oct. 9. District of Brandenburg.— 10th. (?).— 14th. 
 
 Paris, Lyim Eegis. — 15th. Lynn Eegis. — 
 19th. Portugal, Cadiz, the whole of Italy ; of 
 Switzerland; of France; of England; Brus- 
 sels, Li^ge ; the whole of Germany. — 20th, 
 21st. Helmstsedt. — 22nd. Dantzig. 
 
 — Nov. 4. Provence. — 6th. Lynn Eegis. 
 
 — Deo. 1. Germany ; Loebau, Eismark, Seehausen, Wit- 
 
 tenberg, &o.— 7th. (?).— 16th. MontpeUier. 
 — 18th, Versailles ; Geneva ; Nuremberg ; 
 Berlin. — 28rd. Berlin. 
 
 1727. Jan. 15. Giessen ; Durkheim (Hardt) ; Petworth. — 16th. 
 
 Neuch&tel (Switzerland), Liverpool, Lanca- 
 shire. — 17th. Paris. 
 
 — Feb. 9, 11. Utrecht.— 13th. Bologna, Utrecht. 
 
 — Mar. 11. Italy.— 13th. France, Petworth.— 14th. Bo- 
 
 logna, Paris, Petworth, Liverpool, Lynn 
 Eegis, Kaesmark. — 15th. Germany.— 16th. 
 Bologna, Lynn Eegis. — 17th, 18th, 19th, 
 20th. Bologna.— 29th. Italy. 
 
 — April 8. Loebau, Nuremberg. — 14th. Frankfurt on the 
 
 Oder. — 14th. Germany. 
 -- May 13. Bologna. 
 
 — Aug. 1. ' Loebau. — 22Dd. Koenigsberg (?), Germany. — 
 
 27th. KcEnigsberg (?), North Germany. 
 
 — Sept. 9. Loebau. 
 
 — Oct. 13. Germany. — 14th. Paris, Loebau. — 17th. Bo- 
 
 logna, Germany. — 18th. Bologna. — 19th. 
 Paris, Wittenberg. — 20th. Wittenberg. 
 
APPENDIX. 183 
 
 1727. Nov. 6. Germany. 
 
 Numerous auroras were observed by Maraldi 
 during the spring, autumn, and winter of 
 1737 ; the most remarkable are given above, 
 under their dates. 
 
 1728. Jan. 3. Bologna.— 19th. (?). 
 
 — Feb. 7. Utrecht — 9th. Utrecht, Loebau.— 11th. Utrecht. 
 
 — 13th. Paris, Utrecht, BerUn.— 21st, 23rd. 
 Utrecht.— 26th, 29th. Loebau. 
 
 — Mar. 1. Utrecht. — 8th. Plymouth. — 20th. Utrecht, 
 
 Kaesmark. — 26th, 27th. England.— 29th. 
 Germany, Loebau.- 30th. Utrecht. — 31st. 
 Bologna. 
 
 — April 2. Bologna, Windsor, Plymouth, Utrecht, Tesohen, 
 
 Dantzig. — 3rd. Plymouth. — 4th. Wittenberg. 
 —9th. Italy, Utrecht.— 12th. Utrecht. 
 
 — May — . (?).— 30th. Bologna. 
 
 — June — . Germany. — 20th. Wittenberg. — 25th. Berlin, 
 
 Wittenberg. — 29th. Paris, Wittenberg. 
 
 — July — . Utrecht. — 13th. Bologna, Plymouth, Berlin. — 
 
 15th. Plymouth.— 16th. Paris, Utrecht.- 
 28th. Plymouth. 
 
 — Aug. 2, 29. Paris, Plymouth.— SOth. Loebau.— 31st. Ply- 
 
 mouth, Utrecht. 
 
 — Sept. 15. Paris, Utrecht.— 17th. Berlin.— 26th. Italy.— 
 
 29th. Germany.— 30th. Utrecht. 
 
 — Oct. 2. Bologna, Breuillepont, Upminster, Utrecht, 
 
 Zurich, Loebau. — ith. Germany. — 7th. 
 Utrecht, Berlin, Loebau, Wittenberg. — 12th. 
 Plymouth, Utrecht.— 14th, 20th. Loebau.— 
 24th. Windsor, Eodbridge (near Southamp- 
 ton).— 25th, 26th. Plymouth,— 29th. Utrecht. 
 —30th. Italy, Utrecht. 
 
 — Nov. 2. Plymouth, Utrecht, Wittenberg. — 4th. Utrecht. 
 
 —8th. Germany.— 11th, 12th. (?).— 13th. 
 Utrecht, Berlin. — 23rd. Windsor, Utrecht. — 
 24th. (?). 
 
 — Dec. 2. Bologna.— 3rd. Plymouth.— 4th, 14th. Ger- 
 
 many. 
 Auroras frec[uently observed in Paris by 
 Maraldi in all seasons of 1728. 
 1729. Jan. 17. Paris, Plymouth, Loebau. — 18th. Luzin, Ka- 
 wicz. — 20th, 24th. Germany. 
 
 — Feb. 3, 11, 16. Loebau.— 17th. Germany.— 18th. (?).— 
 
 25th. Loebau. 
 
 — Mar. 2. Loebau.— 27th. Utrecht, Lceban.— 28th. Utrecht. 
 
184 THE POLAE AUEOEA. 
 
 1729. April 6. Loebau.— 19th. Germany.— 22nd. Plymouth.— 
 
 30th. Loebau. 
 
 — May 1. Loebau. — ^2nd, 17th. Plymouth. — 22nd. Loebau. 
 
 — 29th. Paris, Loebau. — 81st. Helmstsedt. 
 
 — June 15, 26. Paris. 
 
 — July 7. (?). 
 
 — Sept. 15. Paris.— 23rd. Plymouth.— 26th, 29th. (?). 
 
 — Oct. 2. (?).— 11th. Loebau. — 13th. Paris.— 16th. Loebau. 
 
 —21st. Utrecht.— 22nd. (?).-24th Loebau. 
 —25th. Plymouth. 
 
 — Nov. 16. Paris, Plymouth, Utrecht, Nimeguen, Leipzig, 
 
 Wittenberg, Lcebau, Halle, Hehnstaedt, Ber- 
 lin, &c. (nearly all Germany). — 17th. Paris, 
 Loebau, "Warsaw. — 19th. Brussels, Nime- 
 guen, Loebau. 
 
 — Dec. 17, 18. Loebau. 
 
 1730. Jan. 8. Wittenberg.— 9th. Paris —16th. Loebau. 
 
 — Feb. 4. Paris. — 5th, 7th. Loebau. —9th. Loebau.— 11th, 
 
 13th. (?). — 15th. Bome, Florence, Bologna, 
 all the south of France (Provence, Langue- 
 doc), Paris, Utrecht, Zurich, Geneva, Berne, 
 Eperies (Hungary), Loebau, Brieg (Silesia), 
 Warsaw. — 16th. Loebau, Brieg (Silesia), 
 Warsaw.— 17th. Lcebau.— 20th. (?). 
 
 — Mar. 3. Bologna. — 6th. Bologna, B^ziers, Toulouse, 
 
 France, Plymouth, Utrecht, Germany. — 7th. 
 Toulouse. — 8th. (?). — 9th. Loebau, Germany. 
 — 11th. Bologna. — 13th. Eome, Bologna. — • 
 15th. Bome. — 16th. Loebau. — 18th. Bologna. 
 20th. Plymouth.— 21st. Bologna.— 28th. (?). 
 
 — April 12. Loebau. — 13th. Germany. — 16th. Italy, Bel- 
 
 gium, Lausitz. — 20th. Germany, Bologna. 
 
 — May 9. Loebau. 
 
 — June 5. Zurich. — 21st. Bologna, Germany. 
 
 — July 5, 6. Loebau, Germany. — 17th, 19th. Germany. — 
 
 21st. Ksesmark. 
 
 — Sept. 8. Plymouth.— 10th. Utrecht.— 11th. Italy .—28th. 
 
 Loebau, Wittenberg. — 30th. HaUe, Helm- 
 stsedt. 
 
 — Oct. 4. Loebau.— 5th. Wittenberg, Halle.— 6th. Wit- 
 
 tenberg. — 7th. Toulouse, South of France, 
 Paris, Plymouth, Wittenberg, Helmstsedt, 
 HaUe, Lcebau.— 8th. Berlin. — 9th. Poiotiers, 
 Paris, Breuillepont, Picardy, Frankfurt-am- 
 Main, Wittenberg, Berlin. — 11th. Helmstsedt, 
 
APPENDIX. 185 
 
 Germany. — 13th. Berlin. — 20th. Wittenberg, 
 Hebnstaedt, Loebau. — 21st. Loebau. — 22nd. 
 Germany. — 26th. Geneva, Neuchatel, Boetter- 
 kinden, Zurich, Loebau, Germany. 
 
 1730. Nov. 2. Paris, Vienne (Dauphine), Geneva, Neuchatel, 
 
 Zurich, Loebau, Helmstaedt, Berlin, Branden- 
 burg, Dresden. — 3rd. France, Helmstaedt. — 
 4th. Helmstaedt, Loebau. — 5th. Utrecht, 
 Helmstffidt, Loebau. — 6th. Utrecht, Loebau. 
 — 7th, 8th. Helmstffidt. — 19th. Loebau. — 
 25th. (?).— 28th. Germany. 
 Auroras were seen in Hungary towards the end 
 of the month. 
 
 — Dec. 8, 16, 22, 25. Loebau.— 28th. Jaroslaw.— 29th. Lis- 
 
 bon, Elvas, Campo Maior, Evora, and other 
 parts of Portugal. — 31st. Warsaw. 
 
 1731. Feb. 10. Bologna. 
 
 — Mar. 2. Plymouth.— 7tb. Utrecht. 
 
 — April 3, 13. Utrecht.- 27th, 29th. (?). 
 
 — May 7. Plymouth.— 14th. Utrecht. 
 
 — Aug. 22. Plymouth.— 28th, 31st. Wittenberg. 
 
 — Sept. 24. Plymouth.— 26th. BreuiUepont, Berlin.— 27th, 
 
 28th, 29th, 30th. BreuiUepont. 
 
 — Oct. 2. BreuiUepont, Utrecht, Altorf (Bavaria). — 3rd, 
 
 BreuiUepont, Utrecht, Berlin, Helmstaedt, 
 — 4th. BreuUlepont, BerUn, Heknstsedt, Hil 
 desheim, and to the south of the Danube 
 - — 8th. BreuiUepont, Plymouth, Utrecht 
 Nuremberg, Giessen, Helmstaedt, Wittenberg, 
 Hildesheim, Brandenbxirg. — 10th. Witten 
 berg, Helmstaedt.- 24th, 25th, 26th. BreuUle 
 pont. — 29th. Helmstaedt. 
 
 — Nov. 6. Utrecht.— 11th. Helmstaedt.— 30th. Utrecht. 
 
 — Dec. 30. Plymouth. 
 
 1732. Jan. 26. Wittenberg. — 28th. Paris and neighbourhood. 
 
 —29th. Plymouth. 
 
 — Feb. 2, 4, 5. Paris and neighbourhood. — 7th. Witten- 
 
 berg. — 15th. Paris and neighbourhood. — 
 18th. Plymouth.— 20th, 21st. Germany. — 
 26th. Italy.— 29th. Paris ; Wittenberg. 
 
 — Mar. 1. Paris. — 2nd, 10th. Paris and neighbourhood. 
 
 — 14th, 18th. Germany. — 21st. Utrecht, 
 Berlin, Helmstaedt, Wittenberg. — 22Dd. 
 Germany. — 23rd. Paris and neighbourhood. 
 — 24th. Italy. — 26th. Paris and neigh- 
 
186 THE POLAE AUEOBA. 
 
 bourhood. — 27th. Utrecht ; Helmstaedt. — 
 28th. Paris and neighbourhood. 
 
 1732. April 3, 14, 16, 17. Paris and neighbourhood. — 24th. 
 
 Wittenberg, Beriin.— 23rd, 26th, 27th. Paris 
 and neighbourhood. 
 
 — May 12, 14, 19, 20, 23, 25, 26. Paris and neighbourhood. 
 
 —27th, 28th, 30th. Utrecht. 
 
 — June 25. Heknstsedt. — 26th. Paris ;'Helmstasdt. 
 
 — July 12. Meudon (near Paris). — 17th. Paris and neigh- 
 
 bourhood.— 21st. Italy.— 29th, 30th. Paris 
 and neighbourhood. 
 
 — Aug. 12, 14, 15, 16, 19, 21. Paris and neighbourhood. — 
 
 22nd. Paris, Utrecht, Altorf (Bavaria), 
 "Wittenberg, Berlin, Dantzig. — 23rd. Coburg. 
 
 — Sept. 1, Paris. — 5th. Paris and neighbourhood. — 10th. 
 
 Breuillepont, Wittenberg, Berlin. — 11th, 
 16th. Paris and neighbourhood. — 19th, 20th, 
 21st. Paris, BreuiUepont.— 23rd, 24th, 25th. 
 Germany. — 27th. Breuillepont ; Utrecht ; 
 Berlin. 
 
 — Oct. 1, 2, 3. Breuillepont. — 5th. Paris, Breuillepont ; 
 
 Berlin. — 6th. 14th. Breuillepont. — 20th. 
 Breuillepont. — 22nd. Paris ; Utrecht ; Berlin. 
 — 23rd. Paris, Breuillepont ; Utrecht, 
 Helmstsedt ; Wittenberg, Berlin. — 24th, 
 25 th, 26th. Breuillepont. 
 
 — Nov. 4. BreuiUepont. — ^9th. Paris. — 10th. Utrecht. — 
 
 12th. Utrecht, Germany. — 19th. Utrecht. — 
 20th. Italy, Utrecht, Germany. — 21st. 
 Utrecht. 
 
 — Dec. 4, 13. Neighbourhood of Paris. 
 
 1733. Jan. 19. Paris and neighbourhood. 
 
 — Feb. 13. Plymouth.— 14th, 16th. Neighbourhood of 
 
 Paris. 
 
 — Mar. 3. Bremen, Berlin. — 8th, 9th, 13th. 'Neighbour- 
 
 hood of Paris. 
 
 — April 1. Plymouth.— 2nd, 4th, 5th, 6th, 7th, 8th, 9th, 
 
 10th, 12th. Neighbourhood of Paris.— 13th. 
 Neighbourhood of Paris, Landshut (Silesia.) 
 —18th, 19th. Utrecht.— 22nd. (?) 
 
 — May 4. Utrecht. — 6th. Neighbourhood of Paris. — 7th. 
 
 Utrecht. — 9th. Neighboiirhood of Paris, 
 Utrecht, Wittenberg — 17th. Utrecht. 
 
 — June 20. Neighbourhood of Paris. 
 
 — July 7. Italy, Plymouth, Leipzig; Wittenberg, Berlin. 
 
 —8th, 9th, 10th, 11th, 12th, 13th, 14th, 
 
APPENDIX. 187 
 
 15th. Neighbourhood of Paris. — 21st. Paris, 
 Plymouth. — 22iid. Paris. 
 
 1733. Aug. 3, 4. Paris. — 5th, 6th. Neighbourhood of Paris. — 
 
 7th. Paris.— 8th, 9th, 14th. Neighbourhood 
 of Paris.— 17th, 19th, (?).— 29th. Neighbour- 
 hood of Paris. 
 
 — Sept. 2, 3. Neighbourhood of Paris. — 5th. Utrecht. — 6th. 
 
 Neighbourhood of Paris; Utrecht. — 19th. 
 Plymouth. — 27th. Breuillepont. 
 
 — Oct. 2. Breuillepont, — 3rd. Breuillepont ; Berlin. — 4th, 
 
 5th, 6th, 7th, 8th, 9th. BreuiUepont.— 10th. 
 Paris, Breuillepont; Utrecht. — 16th, 28th, 
 30th, 31st. Breuillepont. 
 
 — Nov. 7. Paris ; Plymouth ; Wittenberg, Berlin. — 8th, 
 
 12th, 13th, 23rd, 24th. Paris. 
 
 — Dec. 8. Paris, Plymouth. — 9th. Paris. — 10th. Paris, 
 
 Plymouth.— 22nd. Berlm.— 2Brd. Utrecht. 
 —27th, 30th. Paris. 
 
 1734. Jan. 8. Neighbourhood of Paris (?).-9th. Servian, 
 
 near B^ziers. 
 
 — Feb. 2. Wittenberg. — 3rd. Paris; Utrecht: Berlin, 
 
 Wittenberg. — 18th. Neighbourhood of Paris. 
 — 22nd. Paris, Bayeux. — 26th. Neighbour- 
 hood of Paris. 
 
 — Mar. 1. Berlin. — 8th. Neighbourhood of Paris. — 22nd. 
 
 Utrecht.— 25th, 26th (?).— 28th, 30th, 31st. 
 NeighboTtthood of Paris (it was not possible 
 to determine whether the phenomenon 
 observed v?as an aurora borealis, or the 
 zodiacal light). 
 
 — Apr. 2, 4. Paris (doubtful). — 5th. Neighbourhood of 
 
 Paris. — 7th. Neighbourhood of Paris, 
 Utrecht.— 8th. Paris; Utrecht.— 9th. 
 Utrecht ; Wittenberg. — 10th. Bologna. — 
 22nd. Potsdam. 
 
 — May 1, 4, 5, 6. Utrecht. — 24th. Neighbourhood of Paris ; 
 
 Utrecht.— 25th, 26th. Plymouth; Utrecht. 
 —27th, 28th, 29th, 30th, 31st. Utrecht. 
 
 — June 1, 2, 4, 5, 7, 24. Utrecht. 
 
 — July 2. Paris.— 5th, 6th, 7th, 8th. Utrecht. 
 
 — Aug. 6, 7, 8. Utrecht.— 20th. Wittenberg.— 23rd, 24th, 
 
 25th, 26th, 30th. Paris and neighbourhood. 
 — 31st. Paris. 
 
 — Sept. 5, 10. Utrecht. — 19th. Nointet (near Beaumont), 
 
 Altorf (Bavaria) ; Berlin. — 20th. Paris, 
 Nointet; Plymouth.— 21st. Utrecht.— 28rd. 
 
188 THE POLAE AUEOEA. 
 
 Nointet ; Berlin.— 25th. Utrecht.— 27th. 
 Nointet.— 29th. Paris ; Utrecht. 
 
 1734. Oct. 1, 2, 5, 6. Utrecht.— 10th. Nointet.— 14th. Utrecht. 
 
 —19th, 21st, 23rd, 25th, 26th, 27th, 28th, 
 29th. Neighbourhood of Paris. — 30th. Paris. 
 
 — Nov. 14, 15, 17, 2a. Neighbourhood of Paris. 
 
 — Dec. 19. Utrecht.— 25th. Paris, Bouen; Utrecht.— 27th. 
 
 Berlin. 
 
 1735. Jan. 23. Utrecht.— 25th. Berlin.— 26th. Utrecht; 
 
 Berlin, Wittenberg. 
 
 — Feb. 11. Utrecht.— 21st. Italy.— 22. Italy; Paris; 
 
 Utrecht ; Berlin, Wittenberg.— 23rd. 
 Utrecht. 
 
 — Mar. 1. Utrecht. — 2nd. Utrecht ; Brandenburg. — 13th, 
 
 15th. Berlin.— 16th, 17th, 19th. Utrecht.— 
 20th. Haarlem ; Germany. — 22nd. Utrecht ; 
 Wittenberg. — 23rd. Utrecht, Haarlem ; 
 BerUn. — 24th. England; Utrecht; Witten- 
 berg; BerHn; Brandenburg. — 25th. Italy; 
 Utrecht; Wittenberg.— 26th, 27th, 28th, 
 29th, 30th, 31st. Utrecht 
 
 — Apr. 20. Utrecht. — 22nd. Utrecht ; Potsdam, Verden. — 
 
 23rd. Utrecht, Haarlem ; Berlin, Potsdam, 
 Brandenburg.— 25th (?) 
 
 — May 14, 17, 18, 19, 22. Utrecht. 
 
 — June 9, 10, 11, 13, 14. Utrecht. 
 
 — July 2, 3, 8, 10. Utrecht. — 17th. Utrecht, Haarlem. 
 
 — Aug. 6, 9, 12, 19, 20, 21, 23. Haarlem.— 31st. Plymouth. 
 
 — Sept. 24. Woodford, near London. 
 
 — Oct. 14. Plymouth.— 15th. London, Plymouth.— 22nd. 
 
 London. — 23rd. Plymouth ; Verden. — 24th. 
 Utrecht.— 25th. Wittenberg. 
 
 — Nov. 10,11. Utrecht.— 14th. Utrecht; Wittenberg.— 
 
 18th. Verden. 
 
 — Dec. 8. Verden.— 11th. Utrecht.— 13th, 15th. Verden. 
 
 1736. Jan. 22. London ; Utrecht. — 31st. Utrecht. 
 
 — Feb. 2. Utrecht.- 9th. Brandenburg.— 17th. Ply- 
 
 mouth ; Altorf.— 18th. Plymouth.— 27 ih. 
 Cambridge. 
 
 — Mar. 1. Plymouth.— 3rd. Utrecht,— 15th. Italy; 
 
 Utrecht ; Brandenburg. — 21st. Branden- 
 burg. 
 
 — April 3. Utrecht. — 5th. Utrecht ; Wittenberg, Branden- 
 
 burg. — 11th. Utrecht. — 14th. London ; 
 Utrecht.— 27th. Utrecht. 
 
 — May 4. Bologna.— 6th, 11th, 14th, 15th, 27th. Utrecht. 
 
APPENDIX. 189 
 
 1736. June 1, 2, 23, 24, 29, 30. Utrecht. 
 
 — July 7, 8. Italy.— 25th. Utrecht. 
 
 — Aug. 12. Berlin.— 13th. Utrecht. 
 
 — Sept. 3. Utrecht, Berhn, Wittenberg. — 4th. Berlin, 
 
 Wittenberg. — 5th, 9th. Plymouth ; Utrecht. 
 —17th. Berlin.— 25th. Bologna ; Sheffield ; 
 Utrecht.— 28th. Utrecht.— 29th. Utrecht; 
 Brandenburg. — 30th. Italy. 
 
 — Oct. 1, 4, 6. Utrecht.— 7th. Plymouth ; Utrecht ; Bran- 
 
 denburg. — 8th. Plymouth. — 10th. Utrecht ; 
 Berlin, Wittenberg.— 11th, 12th. Utrecht.— 
 20th. Utrecht ; Brandenburg. — 22nd. Ooburg. 
 —25th. Paris; Utrecht; Berlin. — 26th. 
 Coburg ; Wittenberg ; Brandenburg. — 27th. 
 Sheffield ; Utrecht ; Coburg ; Wittenberg ; 
 Brandenburg. — 28th. Utrecht ; Coburg ; 
 Silesia ; Pomerania. — 29th. Sheffield ; 
 Utrecht ; Coburg. — 80th. Utrecht ; Coburg. 
 —31st. Utrecht. 
 
 — Nov. 1. Utrecht.— 6th. Berlin. — 7th. Plymouth ; 
 
 Utrecht.— 8th. Utrecht ; Berlin.— 9th, (?).— 
 10th, 11th, 12th. Utrecht.— 18th. Plymouth ; 
 Utrecht.— 19th. Plymouth; Berlin.— 20th, 
 21st. Utrecht.— 24th. Plymouth; Utrecht; 
 Coburg. — 25th, 26th. Utrecht. — 29th. 
 Sheffield. 
 
 — Deo. 15, 18. Utrecht.— 22nd. Paris.— 29th, 30th. Utrecht. 
 
 1737. Jan. 1. Italy.— 4th. Utrecht; Berlin.- 19th. Utrecht. 
 
 —20th. Utrecht; Berhn.— 21st. Paris.— 
 24th. Bologna.— 29th, 30th, 31st. Utrecht. 
 
 — Feb. 2, 20, 28. Utrecht. 
 
 — Mar. 1,4, 8. Utrecht.— 18th. Plymouth.— 21st. Shef- 
 
 field. — 28th. Berlui, Wittenberg. — 29th. 
 Plymouth ; Wittenberg. 
 
 — April 7. Wittenberg. 
 
 — May 3. Utrecht. 
 
 — June 1. Bologna.— 4th, 5th, 17th, 18th, 28rd, 24th. 
 
 Utrecht.— 30th. Bologna. 
 
 — July 26. Utrecht. 
 
 — Aug. 20. Berlin, _ Wittenberg; Brandenburg. — 21st. 
 
 Italy'; Plymouth ; Utrecht ; Wittenberg.— 
 22nd. Plymouth; Utrecht; Berlin.— 23rd. 
 Plymouth ; Berlin, Brandenburg. — 24th. 
 Berlin.— 25th. Italy; Berlin.— 26th, 27th, 
 28th. Utrecht. 
 Sept. 13. Sheffield; Bohemia.— 17th, 19th. Utrecht.— 
 
190 THE POLAE AUEOEA. 
 
 22na. Brandenburg; Goslar.— 27th, 28th, 
 30th. Sheffield. 
 
 1737. Oct. 1. Sheffield; Utrecht.— 2nd. Sheffield.— 17th, 
 
 18th. Utrecht. — 23rd. Brandenburg.— 
 24th, 25th. Sheffield.— 30th. Utrecht. 
 
 — Nov. 12. Plymouth; Brandenburg. — 16th. Dantzig. — 
 
 i8th. Plymouth.— 19th, 20th. Utrecht; 
 Berlin.— 26th. Wittenberg. 
 
 — Dec. 5, Utrecht. — 15th. Utrecht ; - Coburg. — 16th. 
 
 Lisbon; Eome, Bologna, Florence, Ravenna, 
 Arimini, Venice, Paris, England, Utrecht, 
 Vienna, Saxe, Meissen, Annaberg, Sohnee- 
 berg, Wittenberg, Helmstaedt, Berlin, Duis- 
 burg, Brandenburg, Dantzig, Pologne. — 18th. 
 Utrecht.— 19th, (?) 21st, 22nd. Italy.— 24t.h, 
 Arimini. — 26th. Utrecht. — 28th. Italy. 
 Utrecht, Coburg. 
 
 1738. Jan. 3. Brandenburg.— 25th. Plymouth; Utreoht.— 
 
 26th. Utrecht. 
 
 — Feb. 8, 12. Utrecht.- 16th. Italy.— 18th, 19th, 24th, 
 
 26th. Utrecht. 
 
 — Mar. 11, 17. Utrecht.— 18th. Sheffield ; Utrecht.— 21st, 
 
 22nd, 23rd, 26th. Utrecht. 
 
 — April 10. Sheffield.— 13th. Utrecht.— 16th. Plymouth. 
 
 —18th, 21st. Utrecht. 
 
 — May 9, 12, 13, 15. Utrecht. 
 
 — June 5, 8, 16, 17, 23. Utrecht. 
 
 — July 10. Utrecht.— 11th. Italy.— 16th, 21st. Utrecht. 
 
 — Aug. 7. Utrecht. — 13th. Bologna. 
 
 — Sept. 16. Utrecht; Berlin. 
 
 — Oct. 6, 12, 17, 18. Utrecht. 
 
 — Nov. 1. Plymouth.— 4th. Plymouth; Utrecht.— 5th. 
 
 Plymouth.— 7th. Plymouth; Utrecht. 
 
 — Dec. 4. Wittenberg.— 31st. Utrecht. 
 
 1739. Jan. 8, (?)— 27th. Helmatsedt. 
 
 — Feb. 1. Utrecht.— 13th or 14th. Helmstaedt.- 15th. 
 
 Sheffield.— 17th. Helmstffidt.— 27th. Helm- 
 staedt ; Brandenburg. 
 
 — Mar. 6. Sheffield, Plymouth.— 7th. Sheffield.- 10th. 
 
 Bologna, Utrecht.— 11th. Utrecht.— 12th. 
 Sheffield, Pljmiouth, Utrecht, Helmstaedt. — 
 13th, 20th. Utrecht.— 22nd. Helmstaedt.— 
 26th. Plymouth.— 28th. Utrecht.— 29th. 
 Bologna, Padua, London, Chelsea, Utrecht, 
 Helmstaedt, Brandenburg. 
 
APPENDIX. 191 
 
 1739 AprU 2. Berlin. — 5th. Utrecht. — 10th. Plymouth; 
 Wittenberg.— 14th, 15th, 19th. Utrecht.- 
 24th. Berlin.— 29th. Utrecht. 
 
 — May 1. Plymouth, Utrecht, Brandenburg. — 2nd, 3rd, 
 
 4th, 5th, 6th, 8th, 9th, 10th, 11th, 12th. 
 Utrecht. 
 
 — June 2. Bologna ; Utrecht. — 5th, 23rd. Utrecht. 
 
 — July 6, 7, 12, 15, 28, 31. Utrecht. 
 
 — Aug. 1, 6, 7, 10, 12, 13, 28. Utrecht. 
 
 — Sept. 1, 8, 10. Utrecht. — 14th, Dantzig. — 23rd, Ply- 
 
 mouth ; Utrecht. — 24th, Sheffield, Plymouth ; 
 Utrecht ; Brandenburg.— 25th, 26th. Shef- 
 field.— 28th. Utrecht; "Wittenberg.— 29th, 
 30th. Sheffield. 
 
 — Oct. 3, 9, 24, 25. Utrecht.— 29th, (?)— 30th, Plymouth. 
 
 — 31st. Wittenberg, Brandenburg. 
 
 — Nov. 2. Sheffield.- 16th. Italy.— 2l8t. Utrecht.— 23rd. 
 
 Sheffield. 
 
 — Deo. 6. Sheffield. 
 
 1740. Jan. 12. (?).— 27th. Eome.— 30th. Utrecht. 
 
 — Feb. 22. Plymouth. 
 
 — Mar. 23. Plymouth; Utrecht. — 24th, 25th. Plymouth. 
 
 — 28th. Hornburg near Halberstadt. 
 
 — June 7. Plymouth. 
 
 — Oct. 17. Sheffield. 
 
 — Nov. 3. Saint-Port.— 18th. (?) 
 
 1741. Jan. 13. Italy. — 20th. Utrecht. — 22nd. Utrecht ; 
 
 Brandenburg. — 23rd. Utrecht ; Schneeberg, 
 Wittenberg. 
 
 — Feb. 3,6. Utrecht. — 21st. Brandenburg. 
 
 — Mar. 4. (?).— 5. Sheffield.— 6th. (?).— 11th, Sheffield; 
 
 Utrecht. — 12th, 18th. Utrecht. — 16th. 
 Plymouth, Sheffield ; Utrecht ; Brandenburg, 
 —17th. Sheffield.— 20th. Sheffield, Ply- 
 mouth.— 21st, (?).— 29th. Utrecht. 
 
 — April 1. Plymouth.— 6th. (?).— 9th, 16th, Utrecht.— 
 
 17th, (?).— 30th. Utrecht. 
 
 — May 7, 8, 9, 10, 12, 15, 18, 30th. Utrecht. 
 
 — July 10, 23. Plymouth. 
 
 — Aug. 10. Utrecht; Brandenburg. — 13th. Utrecht; Wit- 
 
 tenberg.— 20th, 22nd, 31st. Utrecht, 
 
 — Sept. 1, 3, 4, 12, 19, 20. Utrecht. 
 
 — Oct. 1. (?). — 2nd. Plymouth; Utrecht; Brandenburg. 
 
 —3rd, 4th, 5th. (?).— 8th. Bologna; Ply- 
 mouth ; Utrecht ; Brandenburg ; Wolfsburg 
 
192 THE POLAE AUROEA. 
 
 (LimeboTirg). — 9th. Bologna ; Wolfsbiirg. — 
 13th, 14th, 15th, 28th. Utrecht. 
 1741 Nov. 2. Utrecht; Wittenberg.— 8th. (?).— 9th. "Wit- 
 tenberg. — 12th, 28th. Utrecht. 
 
 — Dec. 14. (?). 
 
 1742. Jan. 2. (?).— 13th, 14th, 23rd. Utrecht.— 26th. Bran- 
 
 denburg.— 29th. Utrecht ; Berlin. 
 
 — Feb. 7. Dantzig.— 12th, 13th. Utrecht.— 23rd. Berlin. 
 
 —25th. Wittenberg. 
 
 — Mar. 8. Plymouth; Wittenb6rg.—7th,8th. Delft.— 13th. 
 
 Utrecht. — 16th, 17th. Plymouth. — 26th, 
 27th. Plymouth; Berlin.— 28th. Utrecht. 
 
 — April 2, 3. Utrecht. — 4th. Plymouth.— 8th, 10th, 24th, 
 
 29th, 30th. Utrecht. 
 
 — May 23. Wittenberg. 
 
 — Aug. 26, 30. Wittenberg. 
 
 — Sept. 7. (?).— 10th. Wittenberg. 
 
 — Oct. 9, 22, 23. (?).— 27th. Utrecht. 
 
 — Dec. 22, 26. Wittenberg.— 28th. Utrecht. 
 
 1743. Jan. 1, 3. Utrecht.— 23rd. Plymouth.— 30th. Witten- 
 
 berg. 
 
 — Feb. 19. Berlin. 
 
 — Mar. 7. Gorlitz, Berlin, Breslau, and probably Dantzig. 
 
 —16th. Wittenberg. — 19th. Plymouth ; 
 Utrecht; Berlin, Dantzig, Zwanenburg. — 
 20th. Utrecht; Wittenberg.— 24th. Italy; 
 Utrecht.— 26th. Utrecht ; Wittenberg.— 
 30th. Utrecht. 
 
 — April 12. Plymouth. 
 
 — July 9. Plymouth. 
 
 — Aug. 9. Utrecht; Zwanenburg.— 12th. Utrecht. 
 
 — Sept. 2. (?).— 8th, 9th, 18th. Utrecht.— 19th. Witten- 
 
 berg.— 29th. (?). 
 
 — Oct. 7. Utrecht.— 8th. Wittenberg.— 25th. Zwanen- 
 
 burg; (?).— 29th, 31st. (?). 
 
 1744. Mar. 4. Berhn.— 19th. The whole of Lithuania. 
 
 — April 2. Plymouth; Utrecht; Wittenberg, Berlin, Dant- 
 
 zig, Zwanenburg. — 5th, 13th, 17th. Utrecht. 
 
 — May 5, 16, 27. Utrecht. 
 
 — July 16, 17. Utrecht. 
 
 — Oct. 3. Bologna. 
 
 — Nov. 11. (?).— 25th. Tubingen. 
 
 — Dec. 3. Glarus.— 25th. Plymouth.— 29th. Tubingen. 
 
 1745. Jan. 4. Plymouth.— 10th. Utrecht.— 18th. Stuttgart, 
 
 Tubingen. — 21st. Wittenberg ; Berlin. 
 
 — Feb. 4, 8. Utrecht.— 17th. Stiiblau, Fiirstenwerder.— 
 
APPENDIX 193 
 
 lath. (?).— 20th. Plymouth.— (?). Ply. 
 mouth (date not given). 
 1745 April 18, 19, 28. Utrecht. 
 
 — May 19, 30. Utrecht. 
 
 — Aug. 2. Utrecht. 
 
 — Oct. 9, 17. Italy.— 31st. Berlin. 
 
 1746. Jan. 12. Zwanenburg.— 26th. Utrecht.— 31st. Tu- 
 
 bingen. 
 
 — Feb. 4. Tiibingen.— 20th. Plymouth.— 23rd. Berg am 
 
 Irchel (canton of Zurich). — 26th. Utrecht. 
 
 — Mar. 10. Plymouth.— 19th. Utrecht.— 25th. Plymouth, 
 
 Utrecht, Zwanenburg. — 26th. Utrecht. 
 
 — April 20, 21. Utrecht. 
 
 — May 7, 12, 16, 17, 26. Utrecht. 
 
 — July 14, 20, 22. Utrecht. 
 
 — Aug. 20, 21, 25. Utrecht. 
 
 — Sept. 21. Berlin (?). 
 
 — Oct. 13. Schneeburg.— 18th. Plymouth.— 19th. Dantzig. 
 
 — 22nd. Utrecht, Tiibmgen.— 23rd, 24th. 
 Tiibingen.— 26th, 28th. Tubingen, Bern- 
 hausen. 
 
 — Nov. 10. Tubingen, Bernhausen. — 17th. Wittenberg. — 
 
 20th. Tubingen, Bernhausen. 
 
 — Dec. 7, 18, 24. Tubingen, Bernhausen. 
 
 1747. Jan. 6. Utrecht, Zwanenburg. — 8th. Plymouth, 
 
 Utrecht.- 9th, 10th, 11th. Utrecht.— 13th. 
 Plymouth. — 22nd. Tubingen. 
 
 — Feb. 1,7. Utrecht.— 13th. Ttibrngen.- 16th. Utrecht. 
 
 — Mar. 10. Zwanenburg.— 17th. Zwanenburg, Berlin. — 
 
 26th. Tubingen. 
 
 — April 2. Plymouth, Utrecht.— 3rd, 5th. Utrecht.— 8th. 
 
 Tubingen.— 9th, 10th, 18th, 29th, 30th. 
 Utrecht. 
 
 — May 2. Utrecht. 
 
 — July 18. Utrecht. 
 
 — Aug. 4, 8. Utrecht. — 31st. Italy, Zwanenburg. 
 
 — Sept. 6. Berlin.— 6th. Utrecht.— 10th. Utrecht, "Wit- 
 
 tenberg. — 13th, 14th. Utrecht. — 27th. 
 Bologna, Utrecht, Zwanenburg, Schneeberg. 
 —29th, (?). 
 
 — Oct. 1. Utrecht, Zwanenburg, — 2nd. Utrecht, Got- 
 
 tingen. — 3rd, 5th. Utrecht. — 9th. Utrecht, 
 GottiQgen.- 19th. Portugal.— 23rd. Tu- 
 bingen. 
 
 — Nov. 23, 24, 27. Steinbronnen.— 28th. Utrecht. 
 
 — Dec. 2. Plymouth, Steinbronnen. — 3rd. Utrecht, 
 
 14 
 
194 THE POLAB AURORA, 
 
 Wittenberg, Berlin. — 17th. Plymouth, 
 Utrecht, Zwanenburg. — 18th. Paris, Utrecht, 
 Dantzig. — 21st. Steinbronnen. — 22nd. 
 Utrecht. — 23rd. Steinbronnen. — 24th. Italy, 
 Berlin. — 26th. Steinbronnen. — 27th. 
 Utrecht. — 29th, 31st. Steinbronnen. 
 
 1748. Jan. 2. Steinbronnen.— 6th, 7th, 20th. Utrecht.— 
 
 25th, 28th. Steinbronnen.— 29th. Utrecht. 
 
 — Feb. 2. Plymouth.— 3rd. Utrecht.— 24th. Stuttgart. 
 
 — 27th. Utrecht, Zwanenburg, Berlin, 
 Wittenberg. — 28th, 29th. Zwanenburg. 
 
 — Mar. 1. Steinbronnen. — 3rd, 5th. Utrecht. — 28th, 
 
 29th. Stuttgart. 
 
 — April 1. Tiibingen.— 20th. Steinbronnen.- 24th, 26th. 
 
 Utrecht.— 27th. Stuttgart. 
 
 — May 1, 2, 12, 21. Utrecht. 
 
 — June 3. Utrecht, Tiibingen, Gottingen. — 4th. Zwanen- 
 
 burg. 
 
 — July 17, 22. Utrecht.— 27th. Berlin. 
 
 — Aug. 1. Utrecht. — 29th. Gottingen. 
 
 — Sept. 6. Gottingen. — 8th. Plymouth. — 11th, 23rd. 
 
 Utrecht. — 27th. Steinbronnen. 
 
 — Oct. 12. Utrecht. — 18th. Steinbronnen. — 22nd, 
 
 Bologna. 
 
 — Nov. 12. Berlin. — 17th. Steinbronnen. — 28th. Dantzig. 
 
 — Dec. 8. DenainviUiers, near Pithiviers. — 14th. Dres- 
 
 den. — 15th. Plymouth. — 16th. Utrecht, 
 Stuttgart.— 18th. Utrecht, Berlin.— 24th. 
 Utrecht, Stuttgart, Berlin, Wittenberg. 
 
 1749. Jan. 10, 18. Utrecht. — 20th, 21st. Stuttgart. — 23rd. 
 
 Utrecht. 
 
 — Feb. 2. Stuttgart. — 9th. Zwanenburg, Berlin. — 11th. 
 
 Utrecht.— 16th. Stuttgart.— 28th (?). 
 
 — Mar. 6, 7. Utrecht.- 10th. Stuttgart, Steinbronnen. — 
 
 11th. Utrecht.— 17th. Stuttgart.— 18th. 
 Plymouth, Stuttgart.— 19th. Berlin.— 21st, 
 23rd. Stuttgart.— 28th. Utrecht.— 31st. 
 Stuttgart. 
 
 — April 2. Utrecht. — 5th. Plymouth, Zwanenburg, 
 
 Berlin.— 7th. Plymouth, Stuttgart.— 9th. 
 Stuttgart.— 10th, 12th. Gottingen.— 14th, 
 16th. Stuttgart.— 17th, 18th. Plymouth. 
 —22nd. Stuttgart. 
 
 — May 3. Stuttgart.— 9th. Plymouth.— lOth. Utrecht, 
 
 Gottingen 12th. Plymouth. 
 
 — July 7. Plymouth.— 8th, 9th, 11th, 12th. Utrecht. 
 
APPENDIX. 195 
 
 1749. Aug. 15, 20. Utrecht. 
 
 — Sept. 17. Bologna.— 22nd. Eome, Bologna, Utrecht, 
 
 Zurich, Tubingen, Steinbronnen, Leipzig. 
 
 — Oct. 8. Bologna, Parma. 
 
 — Nov. 16. Utrecht. 
 
 — Dee. 4. Stoke (Gloucestershire). 
 
 1750. Jan. 1. Zwanenburg. — 3rd. Utrecht. — 5th. Zwanen- 
 
 burg. — 6th. Denainvillers, Utrecht, Leipzig, 
 Berlin, Wittenberg. — 23rd. Tooting. 
 
 — Feb. 3. Naples, Bologna; Toulouse, Paris; Chelsea, 
 
 London, Cambridge, Norfolk, Norwich; 
 Utrecht ; Geneva, Boetterkinden, Zurich ; 
 Zwanenburg, Cologne, Hamburg, Hanover ; 
 Tubingen, Steinbronnen, Leipzig, Witten- 
 berg, Berlin, Dantzig, Wotzlaw near Dantzig. 
 — 4th. Hamburg, Wittenberg, Berlio, Dant- 
 zig. — 6th. Breslau. — 7th. Italy ; Utrecht. — 
 9th. Zwanenburg. — 10th. Gottingen.— 26th. 
 Plymouth.— 27th. . Paris ; Chelsea, Ply- 
 mouth ; The Hague, Utrecht ; Zwanen- 
 burg, Wittenberg, Dantzig. 
 
 — Mar. 4. Utrecht ; Zwanenburg, Tubingen, Stein- 
 
 bronnen, Berlin. — 9th. Utrecht. — 11th. 
 Utrecht; Leipzig. — 12th. Saxony. 
 
 — April 3 Bologna. — 5th. Utrecht. — 8th. Utrecht ; 
 
 Zwanenburg. — 13th. Hamburg, Zwanen- 
 burg, BerHn.— 15th. Plymouth.— 25th, 26th, 
 28th. Utrecht. 
 
 — May 1 Utrecht ; Tubingen, Steinbronnen, Berlin. — 
 
 2nd. Utrecht ; Wittenberg. — 3rd. Utrecht ; 
 Berlin.— 4th, 6th, 7th, 8th, 22nd, 23rd. 
 Utrecht. 
 
 — June 2 Utrecht. 
 
 — July 26 Utrecht ; Zwanenburg, Leipzig. — 27th. 
 
 Utrecht. 
 
 — Aug. 4, 5. Utrecht. — 24th. Paris; Zwanenburg, Witten- 
 
 berg, Berlin. — 26th. Bologna, London, 
 Utrecht ; Zwanenburg, Tubingen, Dresden, 
 Berlin, Dantzig. — 27th. Bologna, Heilbronn. 
 
 — Sept. 2. Utrecht.- 4th. Berlin.— 7th. Utrecht.— 8th. 
 
 Utrecht; Zwanenburg. — 9th. Utrecht. — 
 18th, 19th. Zwanenburg. — 22nd. Plymouth, 
 Leipzig.— 23rd. Plymouth.— 29th. (?). 
 
 — Oct. 12. Northampton. — 13th. Plymouth, Northamp- 
 
 ton.— 21st, 22nd, 26th. Plymouth. 
 
 — Nov. 2. Zwanenburg. — 4th. Plymouth. — 9th. Tubingen. 
 
196 THE POLAE AUEOEA. 
 
 1750. Dec. 14. Bologna, Utrecht.— 19th. Gottingen.— 26th. 
 
 Utrecht. — 28th. Zwanenburg, Tiibingen, 
 Steinbronnen, Grottingen. — 31st. Tubingen. 
 
 1751. Jan. 3, 4. Utrecht.— 19th. Plymouth.— 24th. Utrecht. 
 
 — Feb. 3. Sheffield, Tootmg.— 11th. Tubuigen, Stein- 
 
 bronnen, Gottingen. — 19th. Paris, Witten- 
 berg, Berlin. 
 
 — Mar. 1, 2, 9, 15, 16, 17, 19, 21, 81. Utrecht. 
 
 — April 2. Utrecht.— 17th. Berlin.— 19th, 21st. Utrecht. 
 
 —25th, 26th. Berlin. 
 
 — May 18. Berlin.— 22nd. Utrecht.— 30th. Tubingen. 
 
 — July 28. Berlin. 
 
 — Aug. 19. Bologna, Plymouth, Zwanenburg. 
 
 — Sept. 3. Tubingen.- 11th, 15th. Utrecht.— 19th. Tu- 
 
 bingen.— 28th. Utrecht.— 29th. (?). 
 
 — Oct. 19. Utrecht, — 23rd. Plymouth, Zwanenburg, Tii- 
 
 bingen, Steinbronnen. 
 
 — Nov. 30. Tubingen. 
 
 — Dec. 4. Berlin.— 11th. Plymouth.— 24th. Utrecht. 
 
 1752. Jan. 9. Utrecht.— 18th. Tubingen. 
 
 — Feb. 26, 29. Tubingen. 
 
 — Mar. 2. Utrecht. — 3rd. Utrecht, Zwanenburg. — 6th. 
 
 Tubingen. — 7th. Utrecht. — 8th. Gottingen. 
 —18th, 21st, 22nd, 31st. Utrecht. 
 
 — April 2. Utrecht.— 14th. Zwanenburg. — 19th, 21st. 
 
 Utrecht. 
 
 — May 6, 13. Tubingen.— 17th. Stuttgart.— 22nd. Utrecht. 
 
 — July 16. Tiibingen.- 21st. Stuttgart.— 31st. Tiibingen. 
 
 — Aug. 2. Tubingen.— 4th. Stuttgart.— 23rd. Tiibingen. 
 
 — Sept. 11, 15, 28. Utrecht.- 29th. (?). 
 
 — Oct. 2. Plymouth. — 3rd, 4th, 5th. Zwanenburg. — 12th. 
 
 Denainvilliers, Zwanenburg, Berlin. — 13th. 
 Denainvilliers, Stuttgart, Berlin, Zwanen- 
 burg. — 14th. Plymouth, Zwanenburg. — 19th. 
 Utrecht. — 20th. Zwanenburg. 
 
 — Nov. 8. Zwanenburg. — 17th. Tubingen.— 30th. Ply- 
 
 mouth. 
 
 — Deo. 5. Zwanenburg, Dantzig. — 14th. Tiibingen. 
 
 1753. Jan. 2. Utrecht.— 23rd, 2Jth. Zwanenburg.. 
 
 — April 7. Utrecht. — 20th. Gottingen, Brocken (Harz). — 
 
 24th, 27th. Utrecht. 
 
 — Aug. 27, 31. Utrecht. 
 
 — Sept. 3. Gottingen.— 13th, 17th. Zwanenburg.— 22nd. 
 
 Utrecht. 
 
 — Oct. 11. Zwanenburg. 
 
 — Nov. 28. Utrecht. 
 
APPENDIX, 197 
 
 1753. Deo. 30, 31. Utrecht. 
 
 1754. Jan. 11, 19, 22, 26, 27, 31. Utrecht. 
 
 — Feb. 1. Zwanenburg.— 14th, 15th, 19th, 21st, 23rd, 
 
 27th. Utrecht. 
 
 — Mar. 18. Utrecht, Zwanenburg.— 21st, 24th, 25th, 26th. 
 
 Utrecht. 
 
 — April 12, 15, 16, 18, 19, 23. Utrecht.— 27th. Zwanenburg. 
 
 —28th. Utrecht. 
 
 — May 4. Zwanenburg.— 8th, 9th, 16th, 17th. Utrecht. 
 
 — July 23. Utrecht. 
 
 — Aug. 14, 17, 19, 22, 23. Utrecht. 
 
 — Sept. 21, 24. Utrecht. 
 
 — Oct. 12, 16. Utrecht.— 27th. The Hague. 
 
 — Nov. 14. Utrecht. 
 
 — Dec. 14, 18, 19. Utrecht. 
 
 1755. Jan. 6, 7. Venice.— 15th. Utrecht. 
 
 — April 11, 12, 13, 14, 15. Utrecht. 
 
 — May 4, 5, 7, 15. Utrecht. 
 
 — July 15. Utrecht. 
 
 — Aug. 15, 17. Utrecht. 
 
 — Oct. 3, 10, 14. Utrecht. 
 
 — Dec. 20, 29. Utrecht. 
 
 1756. Jan. 20. Utrecht. 
 
 — Feb. 5. Utrecht.— 15th. Berlin. 
 
 — Mar. 24. Utrecht. 
 
 — April 2. Utrecht. 
 
 — May 4, 7, 20. Utrecht. 
 
 — July 17. Utrecht. 
 
 — Aug. 1. Utrecht. 
 
 — Sept. 14, 17, 24. Utrecht.- 25th. Berlin.— 29th. Utrecht. 
 
 — Oct. 12. Utrecht.- 25th. Berlin.— 26th, 80th. Utreoht. 
 
 — Nov. 18, 20. Utrecht. 
 
 — Deo. 1, 24, 25. Utrecht. 
 
 1757. Feb. 20, 23. Utrecht. 
 
 — Mar. 10, 11, 17, 20, 25, 26, 27, 28. Utrecht.— 31st. 
 
 Eouen. 
 
 — April 1. Bouen.— 14th, 18th, 21st, 23ra, 30th. Utreoht. 
 
 — May 13, 15, 16. Utrecht. 
 
 — Aug. 9, 12, 15, 16, 19. Utreoht.— 26th. Dantzig. 
 
 — Sept. 1, 2. Utrecht.— 16th. Utreoht, The Hague ; Berlin. 
 
 —18th. Utrecht. 
 
 — Nov. 12. London ; Berlin.— 17th. Utrecht. 
 
 — Dec. 6. Berlin (?). 
 
 1758. Jan. 7, 8, 9, 10. Utrecht. 
 
 — Feb. 2. Utrecht; Berlin.— 12th, 13th, 14th, 25th. 
 
 Utrecht. 
 
198 THE POLAR ATJEOllA. 
 
 1758. Mar. 13, 14, 29, 30. Utrecht. 
 
 — April 2. Berlin.— ISth. Utrecht. 
 
 — May 2, 9, 10, ll. Utrecht.— 28th. Zwanenburg. 
 
 — July 27, 28, 99, 80. Utrecht. 
 
 1759. Jan. 20. Zwanenburg. 
 
 — Feb. 4. London ; Berlin. — 5th. London. — 8th. Paris.^ 
 
 20th. Bouen. 
 
 — Mar. 23. London ; Zwanenburg. 
 
 — April 5. Zurich, Woedensweil. — 25th. Zwanenburg. 
 
 — May 11. London. 
 
 — July 28. Zwanenburg. 
 
 — Sept. 16. Bouen, Yvetot ; London ; Hanover, Gottingen, 
 
 Zwanenburg. — 28th. London. 
 
 — Oct. 2, 8, 31. London. 
 
 — Nov. 23. Zwanenburg. — 26th. London ; Zwanenburg. 
 
 — Dec. 23. London. 
 
 1760. July 20. 
 
 Hanover. 
 
 — Aug. 26. 
 
 Zurich. 
 
 1761. Feb. 21. 
 
 Vienna. — 28th. Erlangen; Tymau (Hungary). 
 
 — Nov. 18. 
 
 Berlin. — 19th. Zurich ; Beilin. 
 
 1762. Mar. 21. 
 
 Paris. 
 
 — May 21. 
 
 Paris. 
 
 1763. Jan. 14. 
 
 {') 
 
 — Mar. 23. 
 
 Lausanne. 
 
 — Oct. 12. 
 
 Warsaw.— 16th. Eisenach, Gotha, Erfurt; 
 
 
 Warsaw. — 17th. England ; Eisenach, 
 
 
 Gotha, Erfilrt, Berlin ; Warsaw. 
 
 1764. Mar. 4. 
 
 London. — 6th. Lisbon ; Oxford. 
 
 — April 17. 
 
 Berlin.— 23rd. Oxford. 
 
 — Sept. 29, 
 
 30. Posen. 
 
 1765. Jan. 11. 
 
 Denainvilliers. 
 
 — Mar. 19. 
 
 DenainviUiers. 
 
 — Sept. 2. 
 
 Denainvilliers. 
 
 — Oct. 9. 
 
 Denainvilliers. — 12th. Paris. — 18th. Denain- 
 
 
 villiers. 
 
 1766. Oct. 12. 
 
 Oxford. 
 
 1767. Feb. 6. 
 
 Kiel. 
 
 — Mar. 11. 
 
 Kiel. 
 
 — April 18. 
 
 Environs of Paris. 
 
 — Aug. 5. 
 
 Kiel. 
 
 — Deo. 13. 
 
 Lucqnes. 
 
 1768. Feb. 15, 18. Biel. 
 
 — May. 3. 
 
 Plymouth. — 4th. Plymouth, Bridgwater ; 
 
 
 Kiel.— 5th. Plymouth, Bridgwater.— 24th. 
 Plymouth. 
 Paris; Kiel. 
 
 — Aug, 6. 
 
APPENDIX. 199 
 
 1768. Oct. 28. Rome ; Gurzelen ; Vienna ; Boeringen (Wur- 
 
 temberg) ; Berlin. 
 
 — Dec. 5. Paris, Denainvilliers, NanteuU ; Gurzelen ; 
 
 Vienna ; Boeringen, Gottingen, Berlin. — 6th. 
 Normandy. — 10th. Kiel. 
 
 1769. Jan. 2. Berlin. — 5th. Paris, Montmorency. — 17th, 
 
 18th. Berlin. 
 
 — Feb. 1, 12, 15, 18. Berlin— 24th. Chateau de Broglie 
 
 (Normandy).— 25th. Berlin.— 26th. Cour- 
 lain (Beauce) ; Oxford. 
 
 — Mar. 4. Havre.— 14th, 18th, 26th, 27th. Berlin. 
 
 — April 13, 14, 17, 19, 20. BerHn. 
 
 — May 27. Berlin. 
 
 — Sept. 2. Between Paris and Bayeux. — 9th. Oxford; 
 
 BerHn.— 2l8t. Oxford.— 26th. Burgundy ; 
 Gurzelen ; Vienna ; Boeringen. 
 
 — Oct. 2. Oxford. — 24th. Beziers, Auch, Paris, Rheims, 
 
 Havre ; Vienna, Gruz ; Liibeck, Kiel, 
 Berlin. — 25th. Paris, Havre ; Kiel, Liibeck ; 
 lena, Franecker. — 26th. Paris. — 27th. 
 Havre. 
 
 — Nov. 3. Berlin.— 17th. lena. 
 
 — Deo. 20. DenainviUiers. 
 
 1770. Jan. 17. Hanover, Kiel, Berlin. — 18th. Cadiz, Spain ; 
 
 Naples, Borne, Genoa ; Beziers, Burgundy ; 
 London ; Debreczin, Vienne, Tyrnau ; Aus- 
 pach, Boeringen, lena, Ltibeck, Kiel, Berlin. 
 • — 24th. Kriegsheim (Rhenish Hesse). — 27th. 
 Denainvilliers. 
 
 — Feb. 1. Berlm.— 12th. Gurzelen ; Berlin.— 15th, 18th, 
 
 25th. Berlin. 
 
 — Mar. 14, 18, 23, 26, 27. Berlin.— 29th. lena. 
 
 — AprU 13, 14, 17, 19, 20. Berlin. 
 
 — May 27. (?) 
 
 — July 31. (?) 
 
 — Aug. 1. Liibeck.— 8th, 10th. lena.— 11th. (?).— 28th. 
 
 Paris, Honfleur. — 30tb. Beziers, Normandy. 
 — 31st. Conteville (Normandy) ; Gottingen, 
 Berlin, lena. 
 
 — Sept. 9. Berlin. — 17th. Burgundy, Paris, Montmorency; 
 
 Gurzelen ; Vienna ; Boeringen, Liibeck. — 
 20th. Boeringen. 
 
 — Nov. 8. Liibeck. — 17th. Environs de Paris. — 26th. 
 
 Liibeck. 
 
 — Deo. 17, 24. lena. 
 
 1771. Jan. 6, 15, 18, 20. Berlin. 
 
200 THE POLjtR AUEOEA. 
 
 1771. Feb. 9, 10, 15. Berlin. — 18th. Sparendam. — 19th. 
 
 Montmorency ; Franeoker, Berlin. — 20th. 
 Montmorency. 
 
 — Mar. 6. Montmorency. — 13th. Montmorency ; Fra/- 
 
 necker ; Gurzelen, Berlin. 
 
 — April 4. Berlin. — 5th. Montmorency; Boeringen; Ber- 
 
 lin. — 15th. Montmorency, Berlin. 
 
 — May 2, 3, 6, 7, 8. Berlin.— 12th. lena ; Franecker.— 13th. 
 
 Gurzelen, Franecker. — 28th. Franecker (?). 
 
 — June 2. Ltibeck. 
 
 — July 12. Berlin. 
 
 — Aug. 3. Berlin.— 5th. (?).— 29th. Franecker. 
 
 — Oct. 5, 6. Berlin. — 9th. Berlin, Franecker. 
 
 — Nov. 1. Franecker. — 12th. Berlin. — 13th. Denainvil- 
 
 liers. — 14th. Franecker. — 18th. Berlin. 
 
 — Dec. 5. Franecker. 
 
 1772. Jan. 1, 3. Berlin. 
 
 — Feb. 6. Berlin, Franecker. — 18th. Marseilles. 
 
 — Mar. 2, 3. Franecker.— 5th. Wittenberg, Berlin.— 6th. 
 
 Montmorency. — 7th, 8th, 9th. Franecker. 
 — 22nd. Berlin. — 28th. Berlin, Franecker. 
 —30th. BerUn. 
 
 — April 3. Berlin, Franecker.— 20th, 25th. Berhn.— 29th. 
 
 Franecker. 
 
 — June 14. Marseilles. — 21st, 22nd. Franecker. — (?) two 
 
 auroras seen in June in the south of England. 
 Dates not given. 
 
 — July 18. (?) 
 
 — Aug. 6. (?). — 11th. Franecker. — 31st. Montmorency; 
 
 Berlin. 
 
 — Sept. 1. Franecker.— 20th. Berlin.— 25th, 27th. Fra- 
 
 necker. 
 
 — Oct. 2. Montmorency ; Brussels ; Franecker. — 5th. 
 
 Marseilles. — 6th. Brussels. — 14th. Mar- 
 seilles ; Franecker. — 16th, 20th. Franecker. — 
 23rd. Marseilles; Franecker. — ^26th. Mont- 
 morency. — 27th. Ancona, Padua, Piec^- 
 mont ; Marseilles, Montmorency ; Gurzelen, 
 Vienna ; Boeringen ; lena, Berlin. — 29th, 
 30th. Franecker.- 31st. (?). 
 
 — Nov. 10. (?). — 15th. Marseilles. — 24th. Boeringen; 
 
 Berlin. — ^27th. Berlui. 
 
 — Dec. 3. Marseilles.- 18th. Berlin. — 20th. Marseilles. 
 
 — 24th. Montmorency. 
 1773. Jan. 16. Boeringen, Zutphen.— 17th. Boeringen; Berlin. 
 — 18th. Franecker; Berlin.— 19th. Berhn. 
 
APPENDIX. 201 
 
 —21st. Praneoker; Berlin.— 23ra. (?).— 
 24th. Gurzelen. 
 
 1773. Feb. 1. Franecker.— 18th, 20th, 21st. Franecker, Ber- 
 
 lin. — 22nd. Berlin. — 27th. Boeringen. 
 
 — Mar. 12. Berlin, Franecker. — 13th. Boeringen, Fra- 
 
 necker. — 14th. BerUn, Franecker. — 15th. 
 Paris. — 16th. Franecker. — 21 st. Berhn. 
 — 28rd. Franecker. — 26th. Montmorency ; 
 Franecker, Berlin. 
 
 — April 17. Franecker — 20th. Brussels ; Franecker. — 27th. 
 
 Franecker. 
 
 — May 9. Boeringen. — 11th. Marseilles.— 13th, 17th, 
 
 18th, 19th. Berlin.— 24th, 26th. Marseilles. 
 
 — June 24, 29. Franecker. 
 
 — July 17, 25. Franecker. 
 
 — Aug. 13. Lemgo (Lippe). — 15th, 16th. Breslau. — 18th. 
 
 BerUn. 
 
 — Sept. 1. Marseilles. — 11th. Montmorency ; Franecker. 
 
 —12th. Franecker.- 15th. Berlin.— 22nd, 
 24th. Marseilles. — 27th. DenainviUiers ; 
 Franecker, 
 
 — Oct. 7. Berlin, Franecker.— 8th, 15th. Berlin.— 19th. 
 
 Brussels, Franecker. — 20th. Montmorency ; 
 Brussels ; Boeringen ; Franecker. — 21st. 
 Franecker, Boeringen. — 27th, 28th. Fra- 
 necker. 
 
 — Nov. 7. (?). — 8th. Boeringen. — 17th. Franecker. 
 
 — Dec. 13. Franecker. — 15th. Marseilles ; Boeringen, 
 
 Franecker. 
 
 1774. Jan. 10. Franecker. — 11th. Boeringen, Franecker. — 
 
 12th. Franecker.— 16th, 30th. Boeringen. 
 
 — Mar. 2. Berlin, Franecker. — 3rd. Montmorency ; Brus- 
 
 sels; Franecker; Berlin. — 13th. Franecker; 
 Berlin. — 14th. Montmorency; Buxton, Ken- 
 sington ; Brussels ; Franecker ; Berlin.— 
 15th. Miontmorency ; Brussels; Franecker. 
 —17th. Franecker ; Berlin.— 18th, 20th, 
 * 26th. Franecker. — 30th. Berlin. — 31st. 
 
 Franecker; Berlin. 
 
 — April 1. Berlin. — 4th. Franecker ; Berlin. — 6th, 7th. 
 
 Berlin. — 23rd. Brussels. 
 
 — May 1, 2. Marseilles. — 3rd. Brussels ; Franecker.— 5th. 
 
 Marseilles ; Franecker. — 10th. Franecker. 
 —14th. Cologne.- 16th. Brussels.— 23rd, 
 30th. Franecker. 
 June 6, 7, 12. Liibeck. — 13th. Marseilles.- 15th. Liibeck. 
 
202 THE POLAR AUEOEA. 
 
 1774. July 10. Marseilles.— 13th. Franecker.— 14th. Mar- 
 
 seilles. — 24th, 25th, Franecker. 
 
 — Aug. 1, 2, 3. Franecker.— 21st. Ltibeck ; Franecker. — 
 
 22Qd. Marseilles; Franecker.— 27th, 28th. 
 Marseilles. — 29th. Franecker. 
 
 — Sept. 3, 19. Franecker.— 25th, 26th, 30th. Montmorency. 
 
 — Oct. 1. Berlin. — 6th. The Hague.— 8th. Sparendam. 
 
 —12th. Berlin.— 21st. Franecker.— 27th. 
 Berlin.— 28th, 29th. Franecker. 
 
 — Nov. 3, 5, 11, 30. Franecker. 
 
 — Deo. 1. Marseilles ; Boeringen, Berlin. — 2nd. Boerin- 
 
 gen.— 4th. Marseilles. — 26th, Sparendam. 
 
 1775. Jan. 2. Montmorency.— 3rd, 4th. (?).— 6th. Franecker. 
 
 — 20th, 21st. Montmorency ; Franecker. — 
 23rd, 24th. Franecker; Berlin. — 25th. 
 Franecker. — 28th. Montmorency; Fra- 
 necker. — 30th. Berlin. 
 
 — Feb. 1, 4. Brussels. — 19th. Franecker. — 20th. Bordeaux. 
 
 —21st, 28th. Franecker. 
 
 — Mar. 1, 19, 20, 21, 26, 27, 28, 29, 30. Franecker. Two 
 
 auroras were seen this month at Berlin; 
 dates unknown. 
 
 — April 4, 13, 15, 17, 18. Franecker.- 19th. Louvain; 
 
 Franecker. 
 
 — May 1. Berhn (?).— 2ad, 15th. Franecker.— 19th. The 
 
 Hague. — 20th. Franecker. 
 
 — July 20, 21. Franecker. 
 
 — Aug. 4, 20. Franecker. 
 
 — Sept. 5. Sparendam. — 14th, 15th, 16th. Franecker. — 
 
 17th. Montmorency, Franecker. — 19th. 
 Vu-e.— 22nd, 28rd, 27th. Franecker. 
 
 — Oct. 18. Brussels; Boeringen.— 19th, 20th. BerUn (?). 
 
 — 21st. Vienna ; Sparendam. — 24th, 25th. 
 Franecker. — (?). Leeds. 
 
 — Nov. 6. (?).— 23rd. Franecker. 
 
 — Dee. 15. Franecker, Berlin.— 22nd. Berlin (?).— 23rd. 
 
 Hanover. — 25th. (?). — 26th. Sparendam, 
 Hanover.— 27th. Berlm (?). 
 1776. Jan. 18. Berlin.— 20th. Hanover ; Franecker.- 21st. 
 Franecker; Berhn. — 23rd. (?). 
 
 — Feb. 11, 17, 18, 19, 20. Franecker. 
 
 — Mar. 12, 13. Montmorency.— 26th. Holland— 28th. Mont- 
 
 morency. 
 
 — April 8. Montmorency ; Brussels ; Franecker ; Berlin 
 
 (?).— 10th. Brussels.— 14th. The Hague. 
 — 19th. Franecker. 
 
APPENDIX. 203 
 
 1776. May 3. Brussels. — 21st. Franecker. — 23ra, 25th. 
 
 Brussels. 
 
 — June 6, 7. Brussels. 
 
 — July 7.- Franecker. 
 
 — ■ Aug. 14. Montmorency ; The Hague, Sparendam ; Fra- 
 necker.— 19th, 20th. Berhn (?).— 26th. 
 Franecker. 
 
 — Sept. 3, 4. Franecker. — 5th. Montmorency ; Franecker ; 
 
 Berlin.— 6th, 12th. Franecker.— 16th. Bor- 
 deaux, Montmorency ; Brussels ; Franecker ; 
 Boeringen.— 17th. Berlin (?).— 22nd. Mont- 
 morency; Brussels, Breda, The Hague. — 
 23rd. Montmorency; Brussels; Franecker. 
 — 24th. Franecker. — 25th. Brussels. 
 
 — Oct. 3. Franecker. — 17th. Sparendam.— 27th. Fra- 
 
 necker. 
 
 — Nov. 16. Franecker; Berlin. 
 
 — Deo. 16. Franecker. 
 
 1777. Jan. 13. Montmorency. — 28th. Sparendam, Franecker. 
 
 — 30th. Sparendam. 
 
 — Feb. 5. Montmorency; Sparendam. — 6th. Sparendam. 
 
 — 7th. Montmorency ; Sparendam. — 17th. 
 Sparendam. — 26th. Limoges, DenainyUliers, 
 Paris, Montmorency, Neufmoutiers en Brie, 
 Caen, Havre, Montdidier, Nancy, E^thel, 
 Mazarin, Cambrai, &c. : Breda, Amster- 
 dam, Dordrecht, Middelburg, The Hague ; 
 lena ; Franecker ; Berlin. — 27th. Montmo- 
 rency. 
 
 — Mar. 1. Berlin. — 5th. Montmorency. — 6th. Brussels, 
 
 Breda, Sparendam; Franecker. — 10th, 11th, 
 12th. Franecker.— 13th. Berlin (?).— 17th. 
 (?). — 22nd. Breda, Amsterdam ; Franecker. 
 —25th. Berlin (?).— 28th. Berlin.— 29th. 
 Breda, Sparendam, Franecker; Berlin. — 
 31st. Sparendam. 
 
 — April 1. Brussels. — 4th, 5th. Brussels ; Sparendam, 
 
 Franecker, Berhn. — 6th. Montmorency. — - 
 - 7th, 8th. Brussels ; Franecker. — 9th. Brus- 
 sels, The Hague, Franecker ; Berlin. 
 
 — May 4. Sparendam. — 5th. Breda, Amsterdam, Spa- 
 
 rendam, Leeuwarden, Franecker. — 21st. 
 Leeuwarden. — 30th, 31st. Franecker. 
 
 — June 28. Franecker. 
 
 — Aug. 6. Franecker. — 17th. Berlin. — 24th. Breda, 
 
 Franecker. — 20th. Montmorency; Spa- 
 
204 THE POLAE AUEOEA. 
 
 rendam. — 27th. Montmorency; Sparen. 
 dam, Pranecker, Boeringen. 
 
 1777. Sept. 4. Berlin.— 7tli. He d'Ol^ron, Chinon, Brest, 
 
 Saint- Male, Montmorency; Breda, Pra- 
 necker. — 24th. Montmorency ; Sparendam, 
 Pranecker; Berlin. — 20th. Perpignan. — 
 28th. Pranecker. 
 
 — Oct. 3. Geneva. — 8th, 10th. Pranecker. — 22nd. 
 
 Sparendam, Pranecker. — 24th. Montmo- 
 rency ; Pranecker. — 25th. Pranecker. 
 
 — Nov. 8. Bordeaux, Sarlat, Viviers, Montargis, Denain- 
 
 villiers, Paris, Montmorency ; Breda, Leeu- 
 ■warden, Pranecker ; Vienna ; Boeringen, 
 lena, Berlin. — 6th. Sparendam. — 7th. 
 Sparendam, Pranecker. — 9th. Sparendam. — 
 21st. Breda, Sparendam, Pranecker. — 23rd. 
 Sparendam. — 27th. Bordeaux, Dijon, Mont- 
 argis, Chinon, Montmorency, Strasbourg; 
 Sparendam, Pranecker ; Boeringen, lena. 
 
 — Dec. 1. Sparendam; Berlin (?). — 2nd. Sparendam. 
 
 — 8rd. Perpignan, Limoux, Toulon, Beziers, 
 Viviers, Tarascon, Saint-Gahnier, Dijon, 
 Chinon, Paris, Montmorency, Strasbourg. 
 Lucerne and almost all Switzerland; 
 Vienna; Batisbon, Nuremberg; Boeringen, 
 lena, Berlin, Koenigsberg. — 4th. Berlin. — 
 5th. Montmorency, Berlin. — 6th. Mont- 
 morency; Breda, Sparendam, Pranecker; 
 Vienna. — 17th. Sparendam. — 18th. Spa- 
 rendam, P"ranecker. — 27th. Mannheim. — 
 31st. Chinon. 
 
 1778. Jan. 18. Pranecker.— 19th. Sparendam.— 20th. Pra- 
 
 necker, Sparendam. — 21st. Montmorency, 
 Pranecker, Sparendam. — 25th. Havre ; 
 Vienna; Ulm, lena. — 26th. Pranecker, 
 Sparendam. — 27th. Sparendam. 
 
 — Feb. 16. Chinon, Saint- Malo ; Pranecker. — 17th. 
 
 Chinon, Saint-Malo. — 19th. The Hague. — 
 25th. Marseilles, Bordeaux, Tremblade, 
 Poitiers, Montmorency, Havre ; Breda, 
 Sparendam ; Boeringen ; Vienna. — 26th. 
 Chinon; The Hague, Sparendam. — 28th. 
 Saint-Malo. 
 
 — Mar. 10. Perpignan. — 15th. Gurzelen. — 17th. Beziers, 
 
 Denainvilliers, Montmorency ; Pranecker, 
 Sparendam ; Bceringen. — 18th. Montmo- 
 
APPENDIX. 205 
 
 renoy — 19th. Sparendam. — 22nd. Breda, 
 Franeoker, Sparendam; Berlin. — 25th. 
 Berlin. — 26th. Bordeaux, Chinon, Mont- 
 morency, Eouen, Cambrai ; Breda, Fra- 
 necker; BerUn. — 27th. Franecker. Spa- 
 rendam. — 31st. Berhn. 
 1778. April 14. Switzerland; lena.— 17th. Berlin. — 18th. 
 Lucerne. — 19th. Berlin. — 21st. Breda, 
 Sparendam. — 23rd. Saint- Saturnin (Pro- 
 vence).— 25th. He d'Ol^ron.— 26th. Boe- 
 ringen, Berlin. 
 
 — May 14. Franeoker, Sparendam. — 20th. Brussels. — 
 
 22nd. The Hague. 
 June 8. The Hague.— 10th, 11th, 12th. Franecker.— 
 26th. Havre. — 28th. Cadiz ; Senegal ; 
 B^ziers, Paris, Montmorency, Dieppe ; Fra- 
 necker. 
 
 — July 8. Perpignan.— 7th. Berlin (?).— 9th. Padua; 
 
 Bordeaux; Brussels, The Hague. — 15th. 
 Franecker. 
 
 — Aug. 12. Franecker. — 18th. Berlin. — 22nd. Brussels, 
 
 Breda ; Sparendam, Franecker. — 28th. 
 Brussels, Breda; Berlin. 
 
 — Sept. 15. Franecker. — 17th. Montmorency; Fra- 
 
 necker. — 18th. Sparendam; Berlin. — 19th 
 Viviers, Mur-de-Barrez, Eouergue. — 20th 
 Mur-de-Barrez. — 21st. Bordeaux, Mur-de- 
 Barrez, Viviers, Dijon, Saint-Malo, Mont- 
 morency, Eouen ; Sparendam ; Boeringen, 
 lena. — 22nd. Bordeaux, Tremblade, Chatel- 
 lerault. He d'Oleron, Lu^on, Dijon, Saint- 
 Brieuc, Saint-Malo, Montmorency; Fra- 
 neoker; Vienna; Ukn; lena. — 23rd. Berlin 
 (?).— 24th. Viviers, Dijon, Boeringen.— 27th. 
 Sparendam. — 28th, 29th. Franecker. — 30th. 
 Berlin. 
 
 — Oct. 9. Sparendam.— 18th. Berlin (?).— 14th. He 
 
 d'Oleron, Montmorency, Eouen, Dieppe ; 
 Franecker, Sparendam ; Berlin. — 15th, 19th. 
 Sparendam. — 23rd. Franecker.— 26th, 27th. 
 Sparendam. 
 
 — Nov. 20. Franeoker. — 24th. Sparendam. 
 
 — Deo. 2. Montpellier. — 7th. Sparendam.— 8th. Fra- 
 
 neoker. — 13th. lena. — 14th. Troyes, Mont- 
 morency. — 15th. Sparendam.-^17th. Fra- 
 necker. — 26th. Montmorency. 
 
206 THE POLAR AURORA. 
 
 1779. Jan. 3. Breda.— 6th. Brussels.— 7th. Breda, The 
 Hague, Boeringen. — 9th. Franecker. — 10th. 
 Brussels, Sparendam. — 12th. Sparendam. 
 — 13th. Franecker, Sparendam. — 14th. 
 Sauit-Satumm.— 19th. The Hague, Boe- 
 ringen.— 2l8t. Ingolstadt. 
 
 — Feb. 4, 6. Leeuwarden, Franecker, Sparendam. — 7th. 
 
 Boeringen. — 9th. Spain ; Nancy, Bethel, 
 Cambrai ; Brussels, Breda ; Leyden, The 
 Hague, Amsterdam, Sparendam, Franecker ; 
 Boeringen. — 10th. Spain; Bordeaux, Vienna 
 (Dauphin^), Ohinon, DenainviUiers, Bethel ; 
 Glarus ; Boeringen, Ingolstadt ; lena, Berlin. 
 ■ — nth. Viviers, Vienna, Montmorency; 
 Franecker, Sparendam, Gurzelen ; Boerin- 
 gen; Berlin. — 12th. Vienna, DenainviUiers; 
 Breda, Amsterdam, Sparendam, Franecker. 
 • — 13th. B^ziers, Tarascon, Rodez, Vienna, 
 Nancy ; Gurzelen, Basle ; Vienna ; Boe- 
 ringen, lena, Berlin. — 14th. Beziers, Mar- 
 seilles.^ — 15th. Perpignan, Beziers, Mar- 
 seUles, Tarascon, Viviers, Eodez, Bordeaux, 
 He d'Ol&on, Chinon, Essarts, Montmorency, 
 Eouen ; Brussels, Franecker ; all Switzer- 
 land, Boeringen, lena, Berlin. — 16th. Berlin. 
 — 18th. Nancy. — 19th. Dieppe. 
 
 — Mar. 1. Ingolstadt. — 2nd. Franecker ; Ploskow (Kiev). 
 
 — 14th. Spain; Mur-de-Barrez, Cusset, 
 Nancy, Bethel ; Gurzelen, Boeringen 
 Vienna. — 15th. Batisbon. — 20th. An[ister 
 dam. — 22nd. Boeringen. — 24th. Brussels 
 Franecker. — 25th. He d'Ol&on, Chinon 
 Montmorency, Eouen, Nancy, E^thel 
 Brussels ; Breda, The Hague, Leyden, Am 
 sterdam, Leeuwarden, Franecker ; Boeringen 
 lena. — 26th. Amsterdam.— 30th. Mont- 
 morency; Amsterdam. — 31st. Eodez, Mont 
 morenoy. 
 
 — April 2. Nancy; The Hague. — 3rd. The Hague 
 
 Berlin. — 4th. Franecker. — 6th. Berlin.— 
 7th. Montmorency, Berlin. — 8th. Brussels 
 BerUn. — 9th. Brussels, Breda; Franecker, 
 Sparendam ; Berlin. — 10th. Nancy ; Bob 
 ringen ; Berlin. — 11th. Essarts; Eatis 
 bon. — 13th. Viviers. — 17th. Berlin. — 
 18th. Brussels : Breda, Franecker ; Bee- 
 
APPENDIX. 207 
 
 ringen. — 19th. The Hague. — 20th. Eome ; 
 Brussels, Breda, The Hague, Amsterdam, 
 Sparendam, Praneoker. — 21st. B^ziers, 
 Montmorency; Brussels, Breda, The Hague, 
 Amsterdam, Sparendam, Franecker. — 22nd. 
 Nancy ; Boeringen. — 28th. Brussels, Breda. 
 1779. May 2. Brussels.^th, 6th, 7th, 8th, 10th. Berlin.— 
 11th. Montmorency; Berlin.— 12th, 13th, 
 15th, 17th. Berlin.— 20th. Denainvilliers, 
 Brussels. — 24th. Eodez, Ohinon, Denain- 
 villiers, Nancy, Dieppe ; Breda, The Hague, 
 Leyden, Franecker, Sparendam. 
 
 — June 3, 5. Brussels. —6th. The Hague.— 8th. Padua ; 
 
 The Hague.— 14th, 15th. He d'OWron.— 
 20th. Montmorency.— 24th. He d'OMron. 
 
 — July 9. Bordeaux; Brussels, The Hague. — 15th. Bor- 
 
 deaux ; Brussels. — 17th. Brussels. — 20th. 
 Bordeaux. — 27th. Brussels. 
 
 — Aug. 1. The Hague.— 3rd. The Hague, Franecker. — 
 
 4th. Leyden.— 14th. Eouen.— 17th. Fra- 
 necker. — 29th. Brussels. — 28th. Franecker. 
 — 29th. Montmorency; Sparendam, Fra- 
 necker. — 30th. Nancy. 
 
 — Sept. 8. Sparendam. — 10th. Franecker. — 11th. Spa- 
 
 rendam. — 17th. Saint- Saturnin, Vienna, 
 Cusset ; Brussels. — 18th. Padua ; B^ziers, 
 Marseilles, Tarascon, Viviers, Villefranche, 
 Vienna, He d'Oleron, Pontarlier, Nancy, 
 Montmorency ; Franecker ; all Switzerland, 
 Bceringen ; lena, Berlin, Koenigsherg. — 19th. 
 Mezin (Guienne) ; lena. — 22nd. Agde, 
 Strashourg. — 28th. Franecker. — 29th. 
 Nancy. 
 
 — Oct. 3. Montmorency; Brussels, Breda, Sparendam. 
 
 — 4th. The Hague, Franecker. — 14th. 
 Cusset, Nancy, Montmorency; Brussels, 
 Breda ; The Hague, Leyden, Amsterdam, 
 Sparendam, Franecker, Leeuwarden; Bce- 
 ringen. — 17th. Nancy ; Brussels, Breda, 
 The Hague, Franecker. — 19th. Perpignan. 
 — 20th. Brussels. — 22nd. Sparendam. 
 
 — Nov. 7. Saint-Saturnin.— 8th. He d'Oleron. — 9th. 
 
 Perpignan, Saint-Saturnin, B^ziers, Nantes, 
 Denainvilliers, Montmorency, Nancy; Brus- 
 sels ; Breda, The Hague, Leyden, Amster- 
 dam, Sparendam, Franecker ; Boeringen ; 
 
208 THE POLAR AUEOEA. 
 
 Vienna; Berlin. — 10th. Leeuwarden. — 12th. 
 Lu^on. — 13th. Marseilles, He d'Oleron, 
 Montmorency, Nancy ; Brussels ; Sparen- 
 dam, Leeuwarden. — 14th. Brussels, Berlin. 
 — 15th. The Hague, Leyden, Sparendam. 
 —18th. Nancy. 
 
 1779. Dec. 5. Montmorency, Nancy ; Brussels, Breda ; Am- 
 
 sterdam, Sparendam, Franecker ; Boeringen ; 
 Vienna. — 6th. Montmorency, Nancy ; Brus- 
 sels, Breda; The Hague, Leyden, Amster- 
 dam. Sparendam, Leeuwarden, Franecker ; 
 Gurzelen. — 8th. The Hague ; Franecker. 
 —9th. lena.— 10th. Brussels.— 11th. The 
 Hague, Franecker, Sparendam.— 80th. The 
 Hague. 
 
 1780. Feb. 11. Franecker, Sparendam.— 22nd. Montmorency. 
 
 — 28th. Franecker. — 29th. Spain; Padua, 
 Turin; B^ziers, Montmorency; Franecker; 
 Gurzelen, Geneva, Berne, Lucerne ; Boerin- 
 gen ; Vienna ; lena ; Konigsberg. 
 
 — Mar. 1. Perpignan. — 2nd. London ; Franecker ; Mann- 
 
 heim; Koenigsberg; Pleskov. — 17th. Ber- 
 lin (?).— 29th. Montmorency.— 30th, 31st. 
 Chinon. 
 
 — Apra 2. Berlin (?).— 4th. Berlin.— 6th. lena.— 9th. 
 
 Berlin.— 12th. (?). 
 
 — May 5. Boeringen. — 7th, 8th. (?).— 17th. Lucerne.— 
 
 19th. (?). 
 
 — June 15. Montmorency. 
 
 — July 18. Montmorency. — 20th. Lucerne. — 25th. Boerin- 
 
 gen. — 27th. The Hague. — 28th. Como, 
 Italy ; Montmorency ; Franecker ; Geneva, 
 Gurzelen, Berne ; Boeringen, Frankfort-am- 
 Main, Karlsruhe, Goettingen, lena, Berlin. 
 — 29th. Paris, Montmorency ; Franecker. 
 
 — Aug. 15. Batisbon. — 26th. Franecker. 
 
 — Sept. 4. Franecker ; Berhn. — 3rd. Boeringen. — 4th, 5th. 
 
 Franecker. — 17th. Dantzig. — 22nd, 27th. 
 Montmorency. 
 
 — Oct. 6. lena.— 10th. Berlin.— 30th. EocheUe, Viviers ; 
 
 Geneva ; Franecker. 
 
 — Nov. 3. Montmorency. — 4th. Berlin. — 21st. Eochelle, 
 
 Girard, Saint- Mauritz, Troyes, Franecker. — 
 22nd. Sparendam. — 24th. Boeringen. — 25th. 
 Viviers, Eochelle, Girard, Saint-Mauritz, 
 Troyes, Franecker ; Geneva Gurzelen, 
 
APPENDIX. 209 
 
 Berne; Vienna; Boeringen. — 26th. Eoohelle; 
 Franeoker. — 27th. Montmorency. 
 
 1780. Deo. 3, 5. Montmorency. — 7th. Lucerne ; Berlin.— 19th. 
 
 Denainvilliers ; Berlin. — 30th, 31st. Trieste. 
 
 1781. Jan. 16. Franecker.— 18'h. Padua.— 21st. Abtei St. 
 
 Zenonis. — 28th. Mannheim.^ — 30th. Padua, 
 Beziers, Montmorency; Lucerne; Vienna; 
 Munich, Peissenberg, Kloster Bott, Eatisbon ; 
 Berlin; Sagan. — 31st. Peissenberg. 
 
 — Feb. 5. Montmorency. — 12th. Berne. — 15th. Padua; 
 
 Beziers, Montmorency ; Batisbon ; Berlin. 
 —16th. Mannheim. — 18th. Berlin. 
 
 — Mar. 14. Franeoker; Mannheim; Boeringen, Kloster 
 
 Bott, Wurtemberg. — 19th. Mannheim, Ber- 
 Un. — 20th. Mannheim ; Erfort. — 2Srd. 
 Padua. — 27th. Montmorency ; London ; 
 Franeoker ; Mannheim, Boeringen, Batisbon, 
 Brfilrt. — 28th. Montmorency ; Mannheim, 
 Berlin. — 29th. Montmorency ; Mannheim, 
 Erfiirt; Berhn; Sagan. 
 
 — April 1. Berlin. — 4th. London. — 14th. Mannheim. — 
 
 15th. Montmorency; Erfurt. — 24th. Mann- 
 heim. — 25th. Montmorency. 
 
 — May 4. Batisbon.— 11th, 14th, 16th, 18th. Berlin. 
 
 — June 6. Florence, Eatisbon. — 8th. Mannheim ; Eatis- 
 
 bon; lena. — 19th. Mannheim. — 28th, 29th. 
 Eatisbon. 
 
 — July 6. Franeoker. — 8th. Mannheim. — 17th. Sparen- 
 
 dam. — 20th. Berlin. — 22ud. Montmorency. 
 
 — Aug. 6. Franeoker. — 16th. Wurzburg. — 21st. Mont- 
 
 morency; Mannheim. — 23rd. Sagan. — 25th. 
 Montmorency. — ^26th. Eatisbon, Mannheim. 
 
 — Sept. 2. Mannheim. — 7th. Wm'zburg. — 8th. Mont- 
 
 morency. — 9th. Wurzburg. — 18th. Breda ; 
 Erfurt, Berlin.— 19th. Sagan, Berlin.— 22nd. 
 Prague. — 23rd. Paris, Montmorency ; Boerin- 
 gen, lena, Erfiirt. — 24th. Montmorency ; 
 Maimheim,Iena, Erfiirt, Berlin. — 25th. Mont- 
 morency ; Slough ; Breda, Amsterdam ; Boe- 
 ringen ; Berg St-Ajidex. — 26th. Kloster Bott. 
 
 Oct. 4. Mannheim. — 14th. Prague. — 15th. Padua; 
 
 Montmorency ; The Hague, Franeoker ; 
 Boeringen, Peissenberg, Eatisbon, Kloster 
 Bott ; Sagan. — 16th. Prague ; Erfurt, Sagan. 
 — 19th. Mannheim; Berlin; Sagan. — 21st. 
 Sagan. — 23rd. Padua. 
 
 15 
 
210 THE POLAK AUROEA. 
 
 1781. Nov. 8, 13. Sagan.— 14th. Berlin.— 15th. Erfiirt, Berlin. 
 
 —16th. Boeringen. — 18th. Sagan.— 19th. 
 Mannheim. — 20th. Boeriagen. 
 
 — Dec. 10. Prague. — 11th. Padua; Mannheim, Boeringen ; 
 
 lena ; Berlin ; Sagan. — 12th. Wurzburg ; 
 Berlin.— 13th. Berlin.— 16th, 19th, 22nd. 
 Erfurt. 
 
 1782. Jan. 4. Prague. — 5th. Mannheim. — 7th, 8th. TScerin- 
 
 gen. — 9th. Mannheim ; Sagan. — 10th, 12th. 
 Mannheim. — 17th. Berlin (?). 
 
 — Feb. 2. Berlin (?).— 3rd. Erfiirt, Berlin.— 14th. (?). 
 
 — 15th. Tegernsee. — 16th. Tegemsee ; 
 Prague.— 17th. Tegernsee. — 18th. Era- 
 necker. — 21st. Franecker ; Tegemsee. — ■ 
 22nd. Tegernsee. — 25th. Bologne; B^ziers; 
 Amsterdam ; Prague. — 26th. The Hague. 
 
 — Mar. 5. Franecker.— 6th. Berlin (?).— 9th. The Hague; 
 
 Mannheim ; Sagan. — 10th. Prague, Sagan ; 
 BerUn. — 15th. Montmorency ; Mannheim ; 
 Sagan ; Berlin.- — 17th. Boeringen ; Berlin. 
 —27th. Berlin (?).— 81st. Ratisbon. 
 
 — April 1. Berlin (?). — 4th. Franecker. — 6th. Boeringen. 
 
 ■ — 9th. Lucerne. — 10th. Boeringen. — 13th. 
 Berlin (?).— 22nd. Franecker.— 27th. Mont- 
 morenoy.— 29th, 30th. Berlin (?). 
 
 — May 5. Mannheim. — 7th. Padua; Montmorency. — 8th. 
 
 Berlin (?).— 8th. Mannheim.— 16th, 18th. 
 Vienna,— 20th. Berlin.— 23rd. Berne. 
 
 — June 4. Padua. — 6th, 13th. Mannheim. 
 
 — July 20. Mannheim. — 31st. Padua. 
 
 — Aug. 2. Berlin (?).— 30th. Slough. 
 
 — Sept. 2. Brussels, The Hague. — 6th. The Hague ; 
 
 Sagan. — 10th. Mannheim.— 12th. Padua ; 
 The Hague ; Mannheim ; Berlin. — 18th. 
 The Hague ; Mannheim ; Eatisbon ; Prague. 
 ^15th. Brussels. — 30th. Eochelle, Mont- 
 morency ; Brussels ; Mannheim. 
 
 — Oct. 1. Montmorency; Brussels; Ingolstadt; Sagan, 
 
 Erfurt ; Berlin.— 2nd. Berlin (?).— 3rd. 
 Montmorency ; Sagan. — 8th. Eochelle ; 
 Brussels, Franecker ; Mannheim ; Peissen- 
 berg ; Buda ; Berlin. — 9th. Montmorency ; 
 Middelburg; Eatisbon; Berlin. — 12th. The 
 Hague. — 17th. Berlin. 
 
 — Nov. 7. Eochelle. — 20th. Franecker. 
 
 — Dec. 31. Sagan. 
 
APPENDIX. 211 
 
 1783. Jan. 9. Dijon — 13th. Franecker; Mannheim.— 30th. 
 Erfiirt. 
 
 — Feb. 12. Tegernsee.— 19th. Breslau.— 28th. Liibeck. 
 
 — Mar. 4. Franecker ; Liibeck ; Erfiirt, Sagan. — 16th. 
 
 Berlin.— 18th. Padua.— 20th. lena.— 21st. 
 Leeds ; Sagan. — 22nd. Prague. — 24th. 
 Padua.— 25th. Sagan.— 26th. Slough; Fra- 
 necker.— 27th, 28th. North Germany.— 29th. 
 Montmorency ; Franecker ; Mannheim, Fur- 
 stenfeld, Bavaria ; Sagan, North Germany. 
 — 30th. Eochelle ; Gurzelen ; Mannheim, 
 Diisseldorf ; Sagan, Erfurt ; Berlin ; North 
 Germany. — 31st. Eochelle ; Franecker ; 
 North Germany. 
 
 — April 2. Amsterdam ; Mannheim. — 3rd. Sagan. — 7th. 
 
 Padua ; Franecker ; Middelburg ; Mann- 
 heim. — 9th Brussels; Berlin. — 12th. Leeds; 
 Prague; lena, Berlin. — 14th. Erfurt. — 18th. 
 Berlin. — 20th. Ftirstenfeld. — 21st. Fra- 
 necker ; Fiirstenfeld ; Sagan. — 22nd. Mann- 
 heim. — 25th. Brussels ; Franecker ; Sagan. 
 — 26th. Montmorency; Leeds; Middelburg; 
 Mannheim ; Erfurt ; Sagan. — 27th. Padua ; 
 Eochelle, Dijon, Paris, Montmorency ; Fra- 
 necker, Middelburg ; Dusseldorf, Mannheim, 
 Eatisbon ; Prague ; Goettingen, Erfurt ; 
 Berlin, Sagan. — 28th. Middelburg; Eatis- 
 bon ; Prague. — 29th. Paris, Montmorency ; 
 Franecker, Middelburg; Mannheim; Prague; 
 Goettingen, lena, Erfiirt ; Berlin, Sagan. — 
 30th. The Hague ; Mannheim, Fiirstenfeld 
 (Bavaria). 
 
 — May 1. lena ; Sagan. — 3rd. Prague ; Sagan, Berlin. 
 
 — 4th. Mannheim. — 5th. Mannheim ; 
 Prague. — 12th. Montmorency ; Brusse'- 
 Mannheim. — 16th. Montmorency ; Manu 
 helm. — 17th. Brussels. — 21st. Berlin. — 
 22nd. Montmorency, Laon. — 29th. Mann- 
 heim; Eatisbon. 
 
 — June 1. Padua.— 2nd. (?).— 3rd. Erfiirt.— 19th. Lau- 
 
 sanne. 
 
 July 2. Eatisbon. — 28th. Karlsruhe ; Goettingen. — 
 
 30th. Mannheim. 
 
 — Aug. 1. Franecker ; Mannheim ; Eatisbon. — 8th. 
 
 Prague. — 9th. Eatisbon. — 19th. Berlin. — 
 28th. Northampton. 
 
212 THE POLAE AUEOEA. 
 
 1783. Sept. 4. Mannheim. — 15th. Montmorency, Laon.— 
 
 25th. Mid'delburg ; Prague.— 26th. Fra- 
 necker ; Middelburg. 
 
 — Oct. 22. Montmorency, Laon ; Middelburg ; Buda ; 
 
 Peissenberg ; Sagan, Erfurt ; Berlin. — 23rd. 
 Montmorency, Laon. — 24th. Bochelle. — 
 26th. Dijon.— 27th. Berlin.— 29th. Montmo- 
 rency, Laon ; Prague. — 81st. Montmorency, 
 Laon. 
 
 — Nov. 3. Mannheim. — 11th. Andex. — 13th. Mannheim. 
 
 — 14th. Montmorency, Laon. — 15th. Dijon. 
 —26th. lena. 
 
 — Deo. 3. Berlin (?).— 4th. Mannheim.— 17th. Berlm.— 
 
 18th. Prague. 
 
 1784. Jan. 10. Prague.- 11th. Padua.— 20th, 21st. Bochelle. 
 
 — Feb. 23. London, Kimbolton, Cambridge, Kensington. 
 
 —25th, 26th. HUdesheim. 
 
 — Mar. 5. Mannheim. — 12th. Eatisbon. — 13th, 14th. 
 
 Mannheim. — 15th, 18th. Sagan. 
 
 — April 9. Eatisbon. — 10th. Mannheim. — 16th, 18th. Ber- 
 
 lin. — 21st. Padua. 
 
 — May 6. Peissenberg. — 9th. Laon. — 12th. Paris ; Mann- 
 
 heim. — 17th. Paris ; Delft ; Erfurt, lena. — 
 22nd. Paris. 
 -^ June 16, 17. Rochelle.— 21st. Eatisbon. — 30th. Saint- 
 Veran. 
 
 — July 1. Saint- V^ran.— 3rd. Delft.— 16th. Mannheim. 
 
 — 24th. Berlin. — 25th. Padua ; Paris ; Mann- 
 heim ; Geneva. — 26th. Mannheim. 
 
 — Aug. 4. Prague. — 5th, 15th. Berlin. 
 
 — Sept. 6. Sagan. — 8th. Mannheim. — 11th, 12th. Sagan. 
 
 — 15th. Middelburg, Delft; Mannheim; 
 Furstenfeld, Bavaria ; Prague ; lena, Sagan. 
 —18th. Berlin {?). 
 
 — Oct. 4. Eochelle. 
 
 — Nov. 15. Padua; Dijon, Paris, Laon; Dusseldorf; 
 
 Mannheim ; all Bavaria ; Prague ; Sagan, 
 Erfurt, Berlin. 
 
 — Deo. 31. Sagan. 
 
 1785. Jan. 17. Berlin.— 26th, 28th. Tegernsee. 
 
 — Feb. 3. Tegernsee.— 16th, 17th, 22nd. Mannheim. 
 
 — - Mar. 3. Vienna.— 6th. Sagan.— 22nd. Paris. 
 
 -— April 3. Brussels.- 12th, 27th. Mannheim.— 29th. Eo- 
 chelle ; Berlin. 
 
 — May 1, 15. Brussels. — 23rd. Paris. 
 
 — June 28. Mannheim. 
 
 — July 3, 17. Brussels. — 24th. Mannheim. 
 
APPENDIX. 213 
 
 1785. Aug. 3. Brussels. — 9th. Padua; Berlin. — llth. Brussels. 
 
 —30th. Mannheim.— 31st. Middelburg. 
 
 — Sept. 13. Brussels. — 20th. Berlin. — 23rd. Mannheim. 
 
 — Oct. 4. Sagan ; Berlin. — 5th. Mannheim ; lena. — 6th. 
 
 Middelburg.— 7th. Sagan.— 12th. Berlin.— 
 22nd. La Eochelle. 
 
 — Nov. 2. Laon ; Brussels ; Sagan, Erfiirt ; Berlin — 5th. 
 
 Brussels ; Mannheim ; Berlin. — 6th. Sagan. 
 — 29th. Mannheim ; Sagan ; Berlin. — 30th. 
 Sagan. 
 
 — Deo. 13. Mannheim. — 19th. Berlin. 
 
 1786. Jan. 4. Prague. — 14th. Mannheim. — 18th. Brussels. — 
 
 30th. Tegernsee. 
 
 — Feb. 17. Sagan ; Berlui.— 20th. Berlin.— 28th. Brussels ; 
 
 Berlin. 
 
 — Mar. 19. Paris; Vienna; Prague. — 20th. Erfurt. — 21st. 
 
 Vienna ; Sagan. — 2-2nd. Eome ; Padua ; 
 Marseilles ; Brussels ; Berne, Sutz, Zurich ; 
 Buda ; Munich, Berg Sankt-Andex, Peissen- 
 berg, Tegernsee, Eatisbon ; Prague ; 
 Sagan. — 23rd. Buda ; Sagan. — 25th. Mar- 
 seilles; Mannheim; Berlin. — 26th. Sagan. — 
 28th. Marseilles.— 29th. Marseilles ; Berne ; 
 Sagan. — 31st. Sagan. 
 
 — April 2. Sagan ; Berlin. — 3rd. Brussels. — 18th. Padua ; 
 
 Brussels, Delft ; Eatisbon ; Sagan, Erfurt, 
 lena ; Berlin. — 19th. Sagan. — 20th. Brus- 
 sels ; Mannheim ; Sagan. — 21st. Sagan. — 
 22ijd. Mannheim; Eatisbon, Wurzburg; 
 Sagan, Berlin. — 23rd. Brussels ; Mannheim ; 
 Sagan.— 24th, 25th. Sagan; Berlin.— 26th. 
 Peissenberg ; Prague ; Sagan ; Berlin. — 
 27th. Sagan. — 29th. Brussels, Delft ; Eatis- 
 bon ; Prague ; Sagan. — 30th. Delft. 
 
 — May 1. Paris ; Kendal ; Brussels ; Berlin. — 2nd. Brus- 
 
 sels, Delft ; Berlin. — 3rd. Brussels ; Berlin. 
 — 4th. Berlin. — 5th. Brussels. — 8th. Berlin. 
 — llth. Kendal ; Berlin. — 12th. Brussels. — 
 14th. Paris ; Berlin. — 15th. Brussels ; 
 Prague ; Berlin. — 16th, 17th. Brussels. — 
 18th. Brussels; Berlin.— 19th, 20th. Brus- 
 sels. — 22nd. Eome ; Kendal ; Brussels. — 
 24th. Padua ; Berlin. — 30th. Montmorency ; 
 Sagan. — 31st. Eochelle, Paris, Montmo- 
 rency ; Delft ; Berlin. 
 
 — June 4. Delft.— 5th. Mannheim.— 28th. Delft.— 30th, 
 
 Brussels. 
 
214 THE POLAE AURORA. 
 
 1786. July 5. Paris.— 13th. Paris ; Kendal.— 15th. Kendal.— 
 
 18th. Berlin.— 20th, 22nd. Brussels.— 24th. 
 Brussels ; Berlin. — 25th. Montmorency. — 
 29th. Prague. 
 
 — Aug. 2, 3. Brussels. — 11th. Kendal. — 16th. Brussels. — 
 
 17th. Kendal. — 18th. Montmorency; Brus- 
 sels. — 19th. Brussels. — 21st. Brussels ; 
 Mannheim. — 27th. Mannheim. 
 
 — Sept. 3, 5. Mannheim.— 8th. Kendal. — 19th. Paris ; 
 
 Kendal ; DeUt ; Mannheim ; Berlin. — 20th. 
 Kendal ; Sagan.— 21st, 26th, 29th. tendal. 
 
 — Oct. 2. Bome. — 10th. Mannheim. — 12th. Sagan.— 13th. 
 
 Padua ; Paris ; Kendal ; Delft ; Mannheim; 
 Sagan, Erfurt. — 14th. Padua; Mannheim. 
 — 16th. Mannheim. — 17th. Brussels, Delft, 
 Middelburg ; Mannheim ; Sagan. — 18th. 
 Brussels. — 22nd, 23rd. Sagan. — 25th. Padua; 
 Kendal ; Prague ; lena ; Berlin. — 28th. 
 Sagan. 
 
 — Nov. 5. Berlin (?).— 8th. Paris.— 12th. Mannheun.— 
 
 14th. Kendal. — 20th. Mannheim. 
 
 — Dec. 2. (?). — 3rd. Mannheim. — 5th, 18th. Brussels.— 
 
 20th. Middelburg.— 25th. Kendal.— 28th. 
 Tegemsee. 
 
 1787. Jan. 7. Mannheim. — 9th. Bochelle. — 12th. Kendal.— 
 
 21st. Bologna ; Mannheim ; Sagan. — 22nd. 
 Montmorency ; Mannheim ; Prague ; Sagan, 
 Erfiirt, Gottingen.— 24th. Kendal.— 25th. 
 Paris; Kendal.— 27th. Pragiie.- 29th. Mann- 
 heim. 
 
 — Feb. 6. Berlin (?).— 15th. Bologna, Padua; Paris.— 
 
 i6th, 17th. Wurzburg.— 18th. Sagan.— 22nd. 
 Kendal. — 25th. Mannheim; Prague; Berlin. 
 27th. Prague. 
 
 — Mar. 2. Mannheim. — 16th. Mannheim; Sagan. — 17th. 
 
 Mannheim. — 18th. Paris ; Mannheim ; Mu- 
 nich ; Buda. — 19th. Peissenberg. — 20th. 
 Paris. — 21st. EooheUe, Paris; Kendal; 
 Berne; Mannheim; Mimich, Peissenberg, 
 Eatisbon ; Gottingen, Erfiirt, Sagan. — 22nd. 
 Batisbon. — 24th. Kendal ; Mannheim. — 
 26th. Mannheim. 
 
 — April 1. EooheUe ; Sagan. — 2nd. BocheUe ; Mannheim ; 
 
 Eatisbon ; Gottingen, Erfiirt, lena. — 6th. 
 Sagan. — 12th, 18th. Bologna. — 16th. Sagan. 
 —17th. Mannheim.— 18th. Padua.— 19th. 
 
APPENDIX. 215 
 
 Padua ; Eochelle ; Kendal ; Mannheim, 
 Gottingea, Erfurt, Sagan. — 20th. Eochelle ; 
 Kendal ; Mannheim. — 22nd. Eochelle. — 
 23rd. Mannheim. — 26th. Kendal; lena. 
 1787. May 4. Gottingen.— 10th. Eochelle.— 11th. Eatisbon.— 
 12th. Kendal ; Erfiirt.— 13th. Eome, Padua ; 
 Marseilles, Vienna, Eochelle, Paris, Laon; 
 Buda ; Munich, Eatisbon ; Prague ; Sagan, 
 lena, Eonneburg. — 14th. Padua; Eochelle, 
 Paris. — 15th. Eochelle. — 16th. Paris ; Ken- 
 dal. — 17th. Eome ; Eochelle ; Kendal. — 
 18th. Paris ; Kendal.— 19th. Paris ; Peissen- 
 berg; Erfurt. — 21st. Mannheim. — 25th. 
 Montmorency.— 27th. Berlin (?).— 29th. Eo- 
 chelle. 
 
 — June 5. Eochelle. — 6th. Prague. — 7th. Eochelle; Ken- 
 
 dal. — 8th. Paris. — 10th. Montmorency. — 
 21st. Eome. — 24th. Mannheim. 
 
 — July 11. Erfurt. — 13th. Eome, Bologna, Padua ; Mar- 
 
 seilles, Vienna, Eochelle, Paris, Mont- 
 morency, Laon ; Berne ; Mannheim ; Buda ; 
 Gottingen, Erfiirt ; Sagan ; Berlin. — 14th. 
 Bologna, Padua; Gottingen. — 16th. Bologna. 
 — 20th. Mannheim. — 22nd. Mannheim ; Sa- 
 gan. — 30th. Gottingen; Berlin. 
 
 — Auff. 3. — Prague. — 7th. Paris ; Kendal ; Eatisbon ; Er- 
 
 furt, lena.— 10th. Paris.— 11th. Berlin (?).— 
 19th. Kendal; Mannheim. — 21st. Paris. — 
 24th. Berlin (?).— 25th, 30th. Mannheim. 
 
 — Sept. 6. Bologna ; Paris ; Middelburg ; Gottingen ; 
 
 Sagan. — 7th. Paris ; Mannheim ; lena. — 
 8th. Mannheim. — 10th. Sagan. — 19th. Ken- 
 dal. — 23rd. Mannheim. — 26th. Prague. — 
 28th, 30th. Mannheim. 
 
 — Oct. 1. Sagan. — 4th. Kendal ; lena, Sagan. — 5th. 
 
 Eome, Bologna ; Mannheim ; Prague ; Mvi- 
 nich, Sankt-Andex, Eatisbon, Wurzburg ; 
 Gottingen, Erfiirt, lena, Sagan. — ^6th. Eome, 
 Bologna, Padua; Marseilles, Paris, Mont- 
 morency ; Mannheim ; Berne, Zurich, 
 Geneva ; Buda ; Prague ; Munich, Peissen- 
 berg, Tegernsee, Sankt-Andex, Eatisbon, 
 Wurzburg ; Gottingen, Erfurt, lena, Sagan. 
 — 7th. Padua ; Kendal ; Eatisbon. — 10th. 
 Berne ; Buda ; Munich, Peissenberg, Tegern- 
 see, Eatisbon, Wurzburg; Sagan — 13th, 
 
216 THE POLAE AUEOEA. 
 
 Padua ; Eochelle, Paris ; Berne, Sutz, 
 Geneva ; Buda ; Prague ; Gbttingen, Erfurt, 
 Sagan, Berlin. — 14th. Gottingen, . Berlin. — 
 16tli. Bochelle.— 17th. Marseilles, Eochelle, 
 Paris ; Kendal ; Berne, Geneva ; Prague ; 
 Gottingen ; Sagan, Berlin. — 19th. Kendal. — 
 20th. Berlin.— 21st. Peisaenberg.— 24th. 
 Batisbon ; Buda ; lena ; Sagan. — 31st. Eo- 
 chelle, Paris ; Mannheim ; Berne, Geneva ; 
 Buda ; Prague ; Munich, Tegernsee, Sankt 
 Andex, Eatisbon, Wurzburg ; Erfurt, lena, 
 Sagan. 
 
 1787. Nov. 2. Sagan.— 3rd. Prague.— 4th. Kendal jGottmgen; 
 
 Berlin. — 7th. Sagan. — 8th. Eome ; Paris, 
 Caen, Laon ; Kendal ; Mannheim ; Berne, 
 Sutz, Geneva ; Munich, legemsee, Peissen- 
 berg, Eatisbon ; Prague ; Erfurt ; Sagan. — 
 9th. Brussels ; Mannheim ; Sankt Andex ; 
 Prague ; Sagan. — 10th. Mannheim. — 12th. 
 Wurzburg. — 13th. Mannheim. — 20th. Wurz- 
 burg. — 21st. Montmorency. — 26th. Eome ; 
 Eochelle, Paris, Montmorency ; Mannheim ; 
 Berne, Sutz ; Eatisbon ; Gottingen ; Erfurt, 
 Sagan.— 28th. Kendal.— 29th. Kendal; Ber- 
 lin.— 30th. Kendal. 
 
 — Dec. 6. Eochelle. — 9th. Paris. — 10th. Mannheim; 
 
 Sagan. — 15th. Sagan. — 16th. Berne. 
 
 1788. Jan. 8. Sagan. — 4th. Mannheim. — 5th, 8th. Sagan. — 
 
 9th. Kendal ; Mannheim. — 10th. Kendal, 
 Keswick. — 11th. Kendal; Mannheim; Peis- 
 senberg. — 13th. Kendal. — 14th. Kendal ; 
 Sagan. — 15th. Kendal. 
 
 — Feb. 2. Sagan. — 4th. Kendal; Sagan; Berlin. — 6th, 
 
 7th. Keswick. — 8th. Kendal. — 9th. Sagan. — 
 11th. Spain ; Padua ; Eochelle, Mont- 
 morency; Brussels, Middelburg; Mannheim ; 
 Geneva ; Buda ; Munich, Peissenberg, Te- 
 gernsee, Eatisbon ; Erfurt, lena ; Sagan, 
 Berlin. — 12th. Keswick. — 15th. Eome ; 
 Buda ; Erfiirt, lena. — 22nd. Mannheim. 
 
 — Mar. 7. Eome ; Kendal, Keswick ; Sagan. — 8th. Ken- 
 
 dal ; Sagan. — 14th, 22nd. Mannheim.— 27th. 
 Brussels. — 28th. Paris ; Kendal ; Mannheim. 
 
 — April 1. Paris, Montmorency ; Kendal. — 2nd. Mont- 
 
 morency; Geneva. — 8rd. Kendal; Sagan. — 
 4th. Brussels. — 6th. Sagan ; lena. — 7th. 
 
APPENDIX. 217 
 
 Kendal. — 10th. Eatisbon. — 14th. Kendal.— 
 21st. Mannheim.— 23rd. (?).— 24th, 26th. 
 Sagan. — 27th. Montmorency ; Kendal ; 
 Sagan. — 28th. Kendal, Keswick ; Brussels. 
 — 29th. Paris ; Kendal ; Eatisbon. — 30th. 
 Paris; Kendal. 
 1788. May 1. Kendal.— 2nd. Paris.— Srd. Brussels.— 4th. 
 Kendal. — 7th. Brussels. — 10th. Kendal ; 
 Brussels. — 11th. Kendal. — 24th. Padua ; 
 Paris, Montmorency ; Kendal, Keswick, 
 Dublin ; Brussels ; Mannheim ; Geneva. 
 ■ — 25th. Paris ; Kendal ; Brussels ; Mann- 
 heim. — 26th. Brussels ; Eatisbon. — 27th. 
 Kendal. 
 
 — June 3. Kendal. — 4th. Padua. — 5th, 9th. Brussels. — 
 
 25th. Brussels ; lena. — 27th, 28th. Brussels. 
 
 — July 1. Brussels. — 2nd. Mannheim. — Srd. Paris. — 5th. 
 
 Jena. — 10th. Brussels. — 14th. Mannheim. 
 —15th. Saint-Gothard.— 30th. Paris ; Ken- 
 dal ; Berne ; Eatisbon. — 31st. lena. 
 
 — Aug. 1. EocheUe ; Kendal. — 2nd, Srd. Kendal. — 11th, 
 
 Mannheim. — 19th. Kendal, Keswick ; lena, 
 • — 20th. Eome. — 2Srd. Eome ; Paris ; Ken^ 
 dal, Keswick ; Mannheim ; Geneva. — 24th, 
 Mannheim. — 27th. lena. — 28th. lena, 
 Sagan. — 29th. Kendal ; Mannheim ; Wurz 
 burg; lena, Sagan. — 31st. lena, Sagan. 
 
 — Sept. 1. Brussels ; Sagan. — 2nd. Kendal ; Berne, 
 
 Geneva. — Srd. Erfiirt, lena. — 4th. Paris ; 
 Brussels ; Mannheim ; Eatisbon ; lena, 
 Sagan. — 5th. Eome, Padua ; Mannheim ; 
 Berne, Sutz ; Munich, Tegernsee, Eatisbon, 
 Wurzburg ; Erfiirt, lena, Sagan. — 6th. Ken- 
 dal ; Wurzburg ; Erfiirt. — 7th. Wurzburg. 
 ^lOth. Kendal; lena. — 12th. Mannheim. 
 — 19th. Munich. — 24th. Spain ; Mannheim ; 
 Tegernsee ; Erfiirt, Sagan, lena. — 27th, 29th. 
 
 — Oct, 11. Kendal ; Mannheim. — 12th. Paris ; Sagan.— 
 13th. Paris. — 18th. Sagan. — 21st. Spain; 
 Marseilles ; Kendal ; Mannheim ; Geneva ; 
 Buda. — ;22nd. Spain ; Eome ; Padua ; Mar- 
 seilles, B<5ziers, Eoohelle ; Mannheim ; 
 Geneva ; Buda ; Erfiirt, lena, Sagan. — 24th. 
 Kendal. — 24th. Kendal. — 25th. Sagan. — 
 26th. Geneva.— 27th. Kendal, Keswick; 
 
218 THE POLAR AUEOEA. 
 
 Sagan.— 28th, 29th. Sagan.— 30th. Kendal ; 
 Sagan. — 31st. Paris, Laon ; Kendal. 
 
 1788. Nov. 1. Kendal ; Geneva. — 2nd. Geneva ; Sagan, Er- 
 
 furt.— 3rd, 18th. Sagan.— 19th. Kendal.— 
 23rd. Paris ; Mannheim ; Sagan. — 26th. 
 Sagan.— 27th, 28th, 30th. Kendal. 
 
 — Dec. 8, 15, 16. Mannheim. — 20th. Peissenberg. — 21st. 
 
 Kendal, Keswick.^23rd. Paris ; Brussels ; 
 Berne ; Batisbon ; Sagan. — 24th. Kendal. 
 — 30th. Maimheim. 
 
 1789. Jan. 11. Kendal. — 19th. Sagan. — 21st. Mannheim. — 
 
 22nd. Berlin (?).— 24th. Sagan.— 29th. 
 faris ; Sagan. — 80th. Sagan. 
 
 — Feb. 2. Mannheim. — 4th. Paris. — 15th. Keswick ; 
 
 Berne. — 20th. Sagan. — 23rd. Kendal ; 
 Sagan.— 24th. Paris. — 25th. (?). — 26th. 
 Kendal ; Mannheim. — 28th. Kendal. 
 
 — Mar. 8. Paris. — 14th. Paris ; Kendal, Keswick ; 
 
 Brussels ; Sagan. — 16th. Kendal. — 20th. 
 Mannheim. — 22nd. Sagan. — 27th. Eome ; 
 Mairseilles, Paris. Montmorency; Brussels; 
 Mannheim; Berne, Sutz,- Geneva; Eatisbon; 
 Prague ; lena. — 28th. Eoohelle ; Brussels ; 
 Mannheim ; Berne, Sutz, Batisbon ; Sagan. 
 ^29th. Marseilles ; Kendal ; Brussels ; 
 Sagan. — 30th. Kendal ; Brussels ; Sagan. 
 
 — April 12. Kendal. — 13th. Kendal, Keswick. — 17th. 
 
 Brussels.— 19th, 20th, 27th. Sagan.— 29th. 
 Mannheim; Sagan. — 30th. Kendal. 
 
 — May 15, 16. Brussels. — 17th. Paris ; Mannheim. — 23rd. 
 
 Paris ; Eatisbon. — 24th. Eatisbon. — 28th, 
 29th. Brussels. — 31st. Sagan. 
 
 — June 2, 4. Paris. — 10th. Eatisbon. — 12th. Paris; Kendal. 
 
 —13th, 16th, 19th, 21st. Eatisbon.— 24th. 
 Paris ; Eatisbon. — 30th. Brussels. 
 
 — July 15. Brussels.— 16th. Paris.— 18th, 19th, 20th, 23rd. 
 
 Brussels.— 24th. Paris.— 28th. Laon.— 29th. 
 Brussels. 
 
 — Aug. 13. Keswick. — 14!h. Kendal ; Sagan. — 15th. 
 
 Paris ; Kendal.— 16th, 18th. Kendal.— 19th. 
 Kendal ; Berne ; Peissenberg ; Prague ; 
 Sagan.— 20th. Kendal.— 24th. Paris.— 25th. 
 Paris ; Keswick ; Eatisbon, Sagan. 
 
 — Sept. 14, 15. Kendal:— 17th. Brussels. — 20th. Kendal, 
 
 Keswick ; Sagan. — 21st. Brussels. — 23rd. 
 Kendal. — 24th. Sagan.— 25th. Brussels ; 
 
APPENDIX. 219 
 
 Berne, Sutz ; Mannheim. — 26th. Eochelle, 
 Paris, Falaise, Laon ; Kendal, Keswick ; 
 Brussels ; Berne ; Peissenberg ; Mannheim. 
 —27th. Sagan.— 30th. Paris. 
 
 1789. Oct. 18. Kendal.— 19th. Marseilles; Kendal, Geneva. 
 
 — 20th. Paris ; Kendal ; Brussels ; Peissen- 
 berg; lena; Sagan. — 21st. Brussels. — 23rd. 
 Kendal, Keswick.— 25th, 27th, 31st. Kendal. 
 
 — Nov. 4. Kendal. — 6th. Peissenberg. — 10th. Kendal.— 
 
 14th. Beziers ; Kendal, Keswick ; Sagan. 
 — 15th. Sagan. — 18th. Brussels. — 19th. 
 Kendal, Keswick. — 20th. Sagan. — 21st. 
 Kendal, Keswick. — 22nd. Kendal; Sagan. 
 —24th, 25th, 26th, 27th. Kendal. 
 
 — Deo. 10. Sagan. — 14th. Kendal ; Sagan. — 15th, 16th, 
 
 19th. Sagan.— 20th. Peissenberg.— 22nd. 
 Mannheim ; Sagan. — 24th. Paris. 
 
 1790. Jan. 6. Paris.— 9th, 10th. Sagan.— 14th. Kendal.— 
 
 18th. Mannheim ; Sagan. — 29th. Laon ; 
 Mannheim ; Prague ; lena, Sagan. 
 
 — Feb. 1. Sagan.— 3rd. Kendal.— 4th. (?).— 9th. Kendal. 
 
 12th, 13th. Sagan. — 14th. Mannheim.^ 
 15th. Sagan. — 17th. Brussels. 
 
 — Mar. 2. Mannheim.— 8th. Brussels ; Peissenberg. — 
 
 10th. Kendal.— 11th. Sagan.— 16th. Ken- 
 dal ; Batisbon ; Sagan. — 17th. Kendal ; 
 Sagan. — 18th. Kendal; Mannheim. — 19th, 
 20th. Kendal. 
 
 — April 2. Mannheim. — 3rd, 4th. Kendal ; Mannheim. 
 
 - — 5th. Kendal. — 6th. Kendal; Mannheim. 
 — 7 th. Kendal. — 8th. Mannheun. — 9th. 
 Kendal ; Sagan. — 11th. Mannheim. — 16th, 
 17th. Kendal.— 30th. Brussels. 
 
 — May 12, 14. Kendal. — 16th. Kendal; Peissenberg; 
 
 Prague, Sagan. — 18th. Kendal. — 24th. 
 Brussels. — 28th. Mannheim. — 30th. Prague. 
 
 — June 3. Brussels.- 4th. (?).— 5th, 8th. Brussels.— 22nd, 
 
 Peissenberg. — 25th. Mannheim. 
 
 — July 13. lena. — 16th. Sutz, Switzerland ; Prague. — 
 
 28th. Pavia (?). 
 ^ Aug. 3. Mannheim. — 8th. Paris. — 19th. Berne (?). 
 
 — Sept. 9, 24. Sagan. — 30th. Brussels ; Mannheim ; Sagan. 
 
 — Oct. 1. Mannheim. — 4th. Sagan. — 9th. Kendal, Mann- 
 
 heim. — 14th. Mannheim. — 18th, 31st. 
 Kendal. 
 
 — Nov. 4, 5, 6. Sagan. — 7th. Kendal.— 8th. Kendal; 
 
220 THE POLAE AUEOEA. 
 
 Sagan. — 9th. Kendal ; Mannheim.— -lOth. 
 Kendal. — 12th. Kendal ; Sagan. — 16th. 
 Kendal.— 26th. Sagan.— 27 th. Kendal, Kes- 
 wick.— 28th, 30th. Kendal. 
 
 1790. Dec. 25. Kendal.— 26th. Paris.— 28th. Kendal.— 30th. 
 
 Sagan. 
 
 1791. Jan. 6. Padua ; Kendal, Keswick ; Brussels ; Sagan, 
 
 Berlin. — 7th, 9th. Sagan.— 20th, 25th. 
 Mannheim.— 28th, 29th. Sagan. 
 
 — Feh. 21. Eatisbon.- 24th. Sagan.— 25th. Kendal.— 
 
 27th. Sagan. 
 
 — Mar. 2. Sagan.— 3rd, 5th. Kendal.— 7th. Kendal, 
 
 Keswick.— 20th. Mannheim.— 26th, 29th. 
 Kendal. 
 
 — April 8.- Kendal. — 5th. Sagan. — 13th. Mannheim. — 
 
 18th, 20th, 23rd, 25th. Kendal. 
 
 — May 5. Padna.— 12th, 20th. Kendal.— 23rd. Brussels. 
 
 — 26th. Brussels ; Mannheim. 
 
 — June 10. Kendal. — 19th. Sagan. — 26th. Brussels. 
 
 — July 7. Mannheim. — 20th. Brussels. -l' 
 
 — Aug. 8. Paris. — 18th, 20th. Mannheim. 
 
 — Sept. 5, 8, 11, 13. Kendal. — 15th. Mannheim.- 27th. 
 
 Kendal. — 28th. Kendal ; Brussels. 
 
 — Oct. 6. Sagan.— 15th, 19th, 20th. Kendal. — 21st, 
 
 Brussels. — 22nd. Kendal, Keswick; Brus- 
 sels. — 23rd. Kendal; Sagan. — 28th. Prague. 
 —29th, 31st. Kendal. 
 
 — Nov. 3. Kendal, Keswick. — 4th, 5th. Kendal. — 8th. 
 
 Mannheim.— 11th, 14th. Kendal.— 16th. 
 Sagan. — 17th. Kendal. — 18th. Kendal ; 
 Brussels. — 19th. Sagan. 
 
 — Dec. 13, 19. Kendal.— 2Brd. Brussels.— 26th. Kendal; 
 
 Brussels. — 27th. Sagan. — 28th, 29th. 
 Brussels. 
 
 1792. Jan. 9. Kends^l.- 16th. Sagan.— 17th. Kendal.— 18th. 
 
 Kendal ; Sagan. — 25th. Sagan. — 30th. 
 Brussels. 
 
 — Feb. 9, 17. Kendal. 
 
 — Mar. 2. Kendal. — 4th. Berg Sankt Andex. — 15th. 
 
 Kendal.— 16th, 19th, 25th. Sagan.— 27th, 
 81st. Mannheim. 
 
 — April 10. Montmorency ; Kendal, Keswick ; Sagan ; 
 
 Isserstsedt. — 11th. Kendal, Keswick ; Sagan. 
 —12th. Sflgan.— 13th. Mannheim.— 14th.. 
 Sagan. — 16th. Kendal; Mannheim. — 17th. 
 Brussels. 
 
APPENDIX. 221 
 
 1792. May 6. Kendal.— 8th. Brussels.— 9th, 14th. Sagan.— 
 
 15th. Mannheim. — 20th. Brussels. — 22nd. 
 Montmorency. — 27th. Brussels. 
 
 — June 2. Sagan. — 29th. Kendal. 
 
 — July 16. Peissenberg. — 19th. Brussels. 
 
 — Aug. 1. (?).— 2nd. Sankt Andex.— 4th. Kendal.— 16th. 
 
 Sankt Andex. — 23rd. Kendal. 
 
 — Sept. 1, 6, 14. Mannheun.— 22nd. Kendal.— 28th. Mann- 
 
 heim. 
 
 — Oct. 12. Kendal. — 13th. Marseilles ; Kendal, Keswick ; 
 
 Brussels ; Isserstsedt ; Sagan. — 14th, 15th, 
 16th, 17th. Sagan. — 18th. Kendal ; Sagan. 
 —23rd, 31st. Kendal. 
 
 — Nov. 13, 14. Sagan. — 19th. Kendal, Keswick. 
 
 — Dec. 7. Keswick.— 12th. Padua.— 30th. Sagan. 
 
 1793. Jan. 11, 12, 13. Kendal. 
 
 -T-- Feb. 8. Kendal.— 12th, 15th. Kendal, Keswick. 
 
 — Mar. 4. Paris.— 5th, 6th. Kendal.— 13th, 30th. Ken- 
 
 dal, Keswick. 
 
 — April 5. Kendal. — 9th. Kendal, Keswick. — 14th. Kes- 
 
 wick. 
 
 — May 27. Montmorency. 
 
 — June 9. Montmorency. 
 
 — Aug. 26. Montmorency. 
 
 — Nov. 8. Isserstsedt. 
 
 1794. Jan. 7, 22. Manchester. 
 
 — Mar. 8, 29. Manchester. 
 
 — April 30. Paris, Montmorency. 
 
 — Dec. 7. Viviers, Paris. — 8th. Paris ; Manchester. — 
 
 19th. Manchester. 
 
 1795. Sept. 8, 14. Manchester. 
 
 — Oct. 16, 17. Paris.— 18th. Manchester. 
 
 — Dec. 16, 17. (?) 
 
 1796. Jan. 15. Montmorency. 
 — ■ April . 6. Isserstasdt. 
 
 — May 22. Paris. 
 
 1797. Jan. 22. Manchester. 
 
 — Feb. 1, 18, 17, 28. Manchester. 
 
 — Mar. 1. 2. Manchester. — 10th. Yorkshire. 
 
 — April 24. Manchester. 
 
 — Jime or July (messidor, year V) 3. Eecords of auroras 
 
 without date at Montmorency. 
 
 — Nov. 18, 21, 22, 23. Manchester. 
 
 — Dec. 20. Manchester. 
 
 1798. Jan. 15. Montmorency. 
 
 — Sept. 26. (?) 
 
222 THE POLAE AUEOEA. 
 
 1799. Feb. 25. Eckwarden. 
 
 — July 24. Paris. 
 
 — Sept. 3. Harrogate. — 4th. Paris. 
 
 — Oct. 25. Manchester. 
 
 1800. Mar. 18. Manchester. 
 
 — Aug. 15, 18. Paris. 
 
 — Nov. 2, 7. Manchester. 
 
 — Deo. 10. Manchester. 
 
 1801. Jan. 4, 25. Manchester. 
 
 — Feb. 22. Manchester. 
 
 — Mar. 9. (?). 
 
 — Oct. 6. Manchester. 
 
 1802. Feb. 3. Manchester. 
 
 — Mar. 29. Manchester. 
 
 — June 3. Batisbon. 
 
 — Sept. 27. At sea, off Liverpool. 
 
 — Deo. 13. Manchester. 
 
 1803. Mar. 19. Paris. 
 
 — April 12, 13. Manchester. 
 
 — Sept. 11, 17. Manchester. 
 
 — Oct. 12. Manchester. 
 
 — Deo. 3. Manchester. 
 
 1804. Feb. 2. Manchester. 
 
 — Mar. 29. Paris. 
 
 — April 1, 4. Manchester. 
 
 — May 2. Manchester. 
 
 ' — Oct. 12. Schnepfenthal. — 22nd. Paris ; England ; 
 Bruges ; Prague, Bohemia ; Halle, lena ; 
 Schnepfenthal, Breslau, Berlin ; Koenigs- 
 berg.-23rd, 24th. lena. 
 
 — Nov. 22, 25. Manchester. 
 
 1805. Jan. 1. Manchester, Carlisle. 
 
 — Feb. 23. Manchester. 
 
 — Mar. 26. Carlisle. 
 
 — April 30. Manchester. 
 
 — May 27, 28. Carlisle. 
 
 — Sept. 21. CarUsle.— 22nd. Carlisle ; Berne.— 23rd. Car- 
 
 lisle. — 24th. Paris ; Manchester, Carlisle. 
 
 — Oct. 13, 20, 21. CarUsle.— 22nd. Manchester. 
 
 — Nov. 16, 18, 19, 20, 25, 26. Carlisle. 
 
 — Deo. 26. Carlisle. 
 
 1806. Feb. 7. Manchester. 
 
 — Sept. 12. Manchester. 
 
 — Nov. 2. Manchester; Eckwarden. — 30th. Zurich. 
 
 — Dec. 20. Berlin. 
 
 1807. Jan. 13. Halle.— 26th. Dantzig. 
 
APPENDIX. 223 
 
 1808. Mar. 25. Manchester. 
 
 1809. No aurora borealis recorded this year within the prescribed 
 
 limits. 
 
 1810. Oct. 5. Batisbon. 
 
 1811-1812. No aurora in these two years within the prescribed 
 
 limits. 
 1813. June 24. Augsburg, 
 
 — Sept. 24. Augsburg. 
 
 11314. April 7. Tottenham; Berne.— 15th. Eatisbon.— 17th. 
 Tottenham, England. 
 
 — May 22. Eatisbon. 
 
 — Sept. 10. Manchester. — 11th. Manchester, Kendal. 
 
 1815. Mar. 2. Eatisbon. 
 
 — May 29. Eatisbon. 
 
 1816. May 17. Eatisbon. 
 
 — Sept. 15. Manchester. 
 
 1817. Jan. 8. Berne. 
 
 — Feb. 6. Paris. — 8th. Paris ; Sunderland and many 
 
 parts of England; Berne, Hofwyl, Saint- 
 GaU ; Augsburg ; Prague ; Halberstadt, 
 Leipzig. — 9th. Kosnigsberg.^ — 10th. Eatis- 
 bon.— 18th. Hamm; Prague.— 20th. Walt- 
 hamstow. 
 
 — Mar. 4. Karlsruhe. — 5th. Gordon Castle, Glasgow. 
 — ■ June 12. Eatisbon. 
 
 — - Aug. 16. Eatisbon. 
 
 — Sept. 19. Gosport. 
 
 — Oct. 17. Gosport. 
 
 1818. Jan. 11. Prague and many parts of Bohemia. 
 Feb. 5. Gordon Castle. 
 
 — AprU 4. Eatisbon. 
 
 — Oct. 26. Sunderland. — 31st. Bishopswearmouth (Sun- 
 
 derland). 
 
 1819. Feb. 1. Paris.— 23rd. Prague. 
 
 — Mar. 12. Prague. 
 
 — April 19. , (?).— 26th. Eatisbon. 
 
 — Oct. 6. Zurich. — 7th. Flensburg.— 12th. Manches- 
 
 ter. — 15th. Suffolk. — 17th. London and 
 neighbourhood, Gosport, Manchester, 
 Kendal, Keswick, Seathwaite. — 31st. Gos- 
 port. 
 
 — Deo. 14. London, Manchester. 
 
 1820. Jan. 14. London, Stratford. 
 
 — Feb. 9. Paris (?).— 11th. Manchester. 
 
 — Sept. 6. (?). 
 
 — Nov. 20. Paris. 
 
224 THE POLAE AUEOEA. 
 
 1820. Deo. 4. England. 
 
 1821. Mar. 25. Gosport. 
 
 — Nov. 26. Manchester. 
 
 — Dec. 12. Manchester. 
 
 1822. July 12, 17. Paris. 
 
 1823 No aurora recorded for this year within the prescribed 
 limits. 
 
 1824. Nov. 16. Koenigsberg. 
 
 1825. Oct. 7. Paris. 
 
 — Nov. 7. (?). 
 
 1826. Jan. 5. Kcenigsberg. 
 
 — Mar. 29. Carlisle, Doncaster, Kendal, Keswick, Man- 
 
 cheater, Preston, Penrith, Warrington, White- 
 haven. 
 
 — April 29. Paris, Carlisle. 
 
 — Aug. 29. {?). 
 
 — Sept. 17, 18. (?). 
 
 — Oct. 26, 27. (?). 
 
 1827. Jan. 9. Paris ; Kendal. — 18th. Manchester, Gosport. 
 
 — Feb. 13. Gosport. — 17th. Manchester, Gosport. 
 
 — Aug. 13. (?).— 25th. Paris, Saint-Cloud. 
 
 r— Sept. 8. Saint-Cloud; Berlin.— 9th. Many parts of 
 England. — 25th. Paris, Havre, Arras, Doul- 
 lens; Kendal, England; Ostend, Holland; 
 Aarau, Zurich, Saint-Gall; Stuttgart, Mu- 
 nich, Bavaria ; Prague, Arcona, Apenrade. — 
 26th. Gosport ; Berlin, Stettin ; Apenrade. — 
 28th. Paris. 
 
 Manchester; Allerly. — 17th. Gosport. 
 
 Gosport, AUerly. — 19th. Ajlerly. 
 
 Kendal. 
 
 1828. June 2. Yorkshire. 
 Montmorillon.— 12th, 17th. (?). 
 Prague. — 20th. Chesterfields Lodge near 
 
 Stevenage. — 25th. Gosport. — 29th. Lon- 
 don, Gosport, Kendal, Manchester, Lynn 
 Regis, Penzance, Boreham, Essex, Smedley 
 Hall, Chesterfields Lodge.— 30th. Plymouth, 
 Gosport. 
 
 — Oct. 1. Gosport.— 9th. Manchester.— 31st. Paris (?). 
 
 — Dec. 1. Manchester, Wicksworth (Derbyshire). — 20th. 
 
 (?).— 22nd. CrumpsaU HaU (Manchester).— 
 26th. HuU, Gosport, Manchester, Crump- 
 saU Hall.— 28th. Crumpsall Hall. 
 
 1829. Jan. 2. Manchester. 
 
 — Feb. 11. Berlin. 
 
 Oct. 
 
 6. 
 
 Nov. 
 
 18. 
 
 Dec. 
 
 27. 
 
 June 
 
 2. 
 
 July 
 
 5. 
 
 Sept. 
 
 8. 
 
APPENDIX. 225 
 
 1829. Mar. 4, 6. Crumpsall Hall.— 22nd. Crumpsall Hall, 
 
 Biggleswade. — 29th. England. 
 
 — April 3. Dieppe. 
 
 — May 2. Paris 4th. Crumpsall Hall. 
 
 — June 1. Paris.— 7th. (?).— 17th. Crumpsall Hall. 
 
 — July 25. Kendal, Crumpsall Hall, Manchester. 
 
 — Aug. 1. (?).— 25th. Kendal. 
 
 — Sept. 19. Crumpsall Hall, Manchester. — 21st. Paris. 
 
 — Oct. 2. Kendal. — 3rd. CrumpsaU Hall, Manchester. — 
 
 17th. Manchester.— 25th. Kendal.— 30th. 
 Paris. 
 
 — Deo. 14. London, Gosport. 
 
 1830. Jan. 28. Kendal. 
 
 — Peh. 19. Kendal.— 20th. Gosport. 
 
 — Mar. 18. Manchester. 
 
 — April 19. Manchester, York, and many parts of England. 
 
 — 24th. Manchester, Leeds. 
 
 — May 19. England. 
 
 — Aug. 20. Kendal, Crumpsall Hall. 
 
 — Sept. 7. Gosport, Manchester, Bedford, Isle of Man. 
 
 — Oct. 5. Gosport, Kendal, Carlisle, Bedford, on the 
 
 Atlantic, on 42° 20' lat. N., and 39° 29' long. 
 W.— 9th. Cambridge.— 16th, 17th. Gos- 
 port. — 20th. London. — 22nd. Manchester, 
 Crumpsall Hall. 
 
 — Nov. 1. Gosport, Boston, Bedford, Crumpsall Hall. — 
 
 3rd. Kendal. — 4th. Gosport, Bedford, 
 Crumpsall Hall. — 7th. Gosport, Bedford. — '■ 
 10th. Crumpsall Hall. 
 
 — Dec. 7. Marburg ; Warsaw. — 11th. Gosport, Bedford ; 
 
 Neckarthal (Wurtemberg). — 12th. Gosport, 
 Falmouth, CrumpsaU Hall. — 13th. Gosport, 
 Bedford. — 14th. Gosport, Bedford ; War- 
 saw. — 22nd. Ackworth, Yorkshire. — 25th. 
 Gosport, Kendal, Manchester, Smedley Hall. 
 —20th. Kendal. 
 
 1831. Jan. 6. Crumpsall Hall. — 6th. Gosport, Manchester. 
 
 ■ — 7th. Madrid; Trieste; Paris, Versailles, 
 Strasbourg; Gosport, Bedford, Woolwich, 
 Blaokheath, Falmouth, &c. ; Brussels, 
 Maastricht, Utrecht; Geneva, Basle, Zurich ; 
 Vienna ; Munich, Botzen, Augsburg, 
 Bayreuth ; Brunswick, Wurzburg, Marburg, 
 Elberfeld, Bernburg, Gotha, Leipzig; 
 Breslau, Salzuffeln, Berlin, Colberg, Konigs- 
 berg ; Angerburg ; Brakel ; Cracow ; War 
 16 
 
226 THE POLAE AUEORA. 
 
 Baw. — 8th. Woolwich, Bedford, Falmouth, 
 Gosport, Cnimpsall Hall ; Wurtemberg. — 
 ipth. Falmouth, Crumpsall Hall.— 11th. 
 Kendal, Gosport, Bedford, Falmouth, Heron 
 Court.— 14th. Falmouth; Atlantic— 15th, 
 16th. Atlantic. — 21st. Manchester. 
 
 1831. Feb. 11. Manchester, Crumpsall Hall. — 14th. Crump- 
 
 sail Hall, Lancaster. — 15th. Falmouth. — 
 17th. Falmouth, Lancaster. — (?). Kenac, 
 near Bennes. 
 
 — Mar. 6. Crumpsall Hall. — 7th. GrumpsaU Hall, Heron 
 
 Court ; Buchholtz near Frankfort-sur-Oder. 
 — 8th. Manchester, Gosport. — 11th. Man- 
 chester, Marsden, Gosport, Lancashire. — 
 12th, 13th. Crumpsall Hall. 
 
 — April 3. Crumpsall Hall. — 19tb. Manchester, Gosport ; 
 
 Berlin. — 20th. Gosport ; Berlin, Kitzingen, 
 — 23rd. Manchester. 
 
 — May 30. Gosport. 
 
 ,— July 14. (?).— 20th. Gosport. 
 
 — Aug.3,5. Eome.— 7th. (?).— 12th. Paimboeuf.— 26th. 
 
 Basle. — Both. Augsburg. 
 
 — Sept. 12. Manchester, Gosport. 
 
 — Oct. 29. Manchester, Gosport. — Several auroras at 
 
 Kendal in September and October, precise 
 dates not given. 
 
 — Nov. 8. Wurtemberg. 
 
 — Dec. 9, 22. Paris. 
 
 1832. Jan. 14, 15, 16. (?).— 27th. Manchester. 
 
 — Feb. 2. Giengen (Wurtemberg).— (?). Paris (?). 
 
 — Sept. 17. Cambridge, Manchester and district, York, 
 
 Dent near Kendal, Armagh. — 23rd. Man- 
 chester, Smedley HaU. 
 
 — Oct. 12. England. 
 
 — Nov. 1. Manchester, Bradford, Burnley, Kendal, &c. — 
 
 4th. Lincoln. 
 
 — Dec. 21. Newcastle upon Tyne ; Allerly. 
 
 1883. Feb. 11. Manchester. — 18th. CrumpsaU HaU. — 19th. 
 Manchester. 
 
 — Mar. 13. Cambridge. — 21st. Manchester ; observ. of 
 
 Armagh, Athboy (Ireland). 
 
 — Aug. 6. Crumpsall Hall. 
 
 — Sept. 1. Carhsle.— 14th. York, Greta-Bridge.— 15th. 
 
 Burn. — 17th. London, Cambridge, York, 
 Gosport, Manchester, Ireland — IRth. Man- 
 chester. 
 
APPENDIX. 227 
 
 1833. Oct. 19. Paris; Cambridge, Manchester, York, Heron 
 
 Court, Guisborough, Dent, Armagh. 
 
 — Nov. 12. Brussels. 
 
 1834. Jan. 5. Catterick Bridge (Yorkshire).— 15th. Brussels. 
 
 — Feb. 10. Augsburg.— 20th. Kendal. 
 
 — June 28. Brussels. 
 
 — July 8. (?). 
 
 — Sept. 21. (?). 
 
 — Nov. 3. England. 
 
 — Deo. 21. England. — 22nd. Woolwich ; Braunsberg 
 
 (eastern Prussia), Kcenigsberg. 
 
 1835. Jan. 4. Augsburg. 
 
 — Feb. 7. England; Gottingen; Braunsberg, Germany. 
 
 — 27th. Braunsberg. 
 
 — July 3. (?). 
 
 — Nov. 16. Woolwich. — 17th. Paris ; London, Ashurst, 
 
 Dulwich and many parts of England; 
 Hanover; Berlin. — 18th. Nlmes, Cahors, 
 Paris, Caen, Corbigny, Cherbourg; London, 
 Chiswick, Greenwich, Woolwich, Oxford, 
 Banbury, Deal, Collumpton; Armagh, Ire- 
 land ; Brussels ; Oldenburg. — 19th. Paris. 
 
 1836. April 22. Channel Islands ; High-Burns near Sunder- 
 
 land. 
 
 — May 15. Sunderland.— 20th. Paris.— 24th. (?). 
 
 — .Aug. 10. Byde. 
 
 — Sept. 29. Dublin. 
 
 — Oct. 5. Dublin. — 11th. Dublin, Leominster ; Zurich ; 
 
 Braunsberg. — 12th. Zurich ; Braunsberg. 
 ■ — 18th. Spain; Parma, Forli, Turin; 
 Cahors, Chamb^ry, Paris, Strasbourg, Caen, 
 Cherbourg, Corbigny, Eennes, Nantes; 
 London, Londonderry and many parts of 
 England ; Brussels, Liege ; Aix-la-OhapeUe, 
 Elberfeld, Cologne, Dusseldorf, Mayence; 
 Wiesbaden, Karlsruhe ; Stuttgart, Frankfort- 
 on-Mein; Zurich, Basle, Geneva; Inns- 
 briiok ; Prague ; Osnabriick, Hanover, Got- 
 tingen ; Dresden ; Berlin, Swinemunde, 
 Colberg, Braunsberg, Danzig, Heiligenbeil, 
 Elbing, Konigsberg ; Lamberg ; Warsaw. 
 —19th. Zurich. 
 
 — Nov. 15. Brest. — 27th. Hanover. 
 
 1837. Jan. 25. Basle, Zurich, nearly all Switzerland; Stutt- 
 
 gart, Giengen, Bubach. — 26th. Giengen. — 
 27th. Mechlin. 
 
228 THE POLAE AUEOEA. 
 
 1837. Feb. 2. (?).— 13th. Zurich ; Konigsberg and district. 
 —14th. Zurich.— 18th. Eome, Forfi, Pise, 
 Venice, coast of Istria, Parma, Milan ; 
 Marseilles, Montpelher, Paris, Meaux, Luz- 
 arches, Versailles, Beauvais, Morlaix, Sar- 
 reguemines; London, Devonshire, Kent, 
 Belfast, Sidmouth, Athurst; Zurich, Basle, 
 Geneva ; Prague ; Stuttgart, all Swabia ; 
 Cologne, Nuremberg; Gottingen, Gotha, 
 Halsbruck, Gnadenfeld (Silesia). 
 
 — Mar. 29. Zurich, Switzerland. 
 
 — April 6. Anglers ; Breslau. — 7th. Munich. 
 
 — May 2. Breslau. — 19th. England. 
 ~ June 24. England. 
 
 — July 1, 2, 7. England. — 28th. Mannheim, Stuttgart; 
 
 Vienna. 
 
 — Aug. 4. Naples. — ^25th. England. 
 
 — Sept. 22. Brussels.— 23rd. Hamburg.— 29th. Dublin. 
 
 — Oct. 6. Paris. — 11th. England. — 18th. Parma; Paris; 
 
 Geneva, Zurich, Switzerland; Bamberg, 
 HUdburghausen, &c., and all Germany ; 
 Warsaw. — 19th. Geneva. — 2l8t. Warsaw. 
 —22nd. Atlantic 40° 22' lat. N. and 38° 
 54' long. W. 
 
 — Nov. 6. Paris, Brest, Ushant ; London ; Leipzig. — ■ 
 
 12th. Parma, between Genoa and Leghorn ; 
 Montpellier, Anglers, Vendome, Jambles 
 near Givry, Paris, Athurst, Dulwich, &c., 
 England ; Brussels ; Aix-la-Chapelle ; Basle ; 
 Prague ; Augsburg, Wurzburg ; Kirchheim 
 (Hesse), Hildburghausen, Gotha, Hanover; 
 Berlin, Stettin. — 14th. Paris, Jambles near 
 Givry, Brest ; Basle ; Augsburg ; Hanover ; 
 Cracow. — 15th. Paris, Brest. 
 1833. Jan. 6. (?).— 29th. Stuttgart, Wurtemberg. 
 
 — Feb. 18. England. 
 
 — AprU 29. Brussels. 
 
 — Sept. 18. Paris ; Athurst, Dulwich. — 15th. Paris. 
 
 — Nov. 12. Slough; Bremen; Eutin. — 13th. Paris. 
 1839. Jan. 2. Milan. — 6th. Parma. — 10th. Hamburg and 
 
 in the north. — 12th, 14th. Parma.— 17th. 
 Brussels. — 18th. England. — 19th. Chiswick, 
 Athurst, Dulwich, Dublin ; Brussels. 
 
 — Feb. 21. Eutin. 
 
 — May. 5. France ; England ; Brussels. — 7th. Parma, 
 
 Saint-Brice near Ecouen. 
 
APPENDIX. 229 
 
 1839. Aug. 30. Warsaw. 
 
 — Sept. 1. Zurich. — 3rd. Turin, Alexandria, Asti ; Paris ; 
 
 London, Athurst, Dulwich ; Brussels ; many 
 parts of Wurtemberg ; G'ottiiigeii. — 25th. 
 
 — Oct. 16. Douai. — 22nd. Madeira ; Eome, Pesaro ; 
 
 MarseUles, Aix, Toulouse, Paris, Meaux, 
 Commeroy, Strasbourg, Benac near Eennes ; 
 Brussels ; Geneva ; Stuttgart and many 
 places in Wurtemberg; Berlin, Eutin. — 
 23rd. Eutin. 
 
 — Nov. 1. Eutin. — 12th. Prague. 
 
 — Dec. 14. Gosport. 
 
 1840. Jan. 3. Huggate ; Geneva ; Halle. — 11th. Geneva. 
 
 — Feb. 6. Cracow. — 17th. Einsiedeln, Switzerland. — 
 
 25th. Brussels. 
 
 — Mar. 11. (?). 
 
 — April 24. Dublin. 
 
 — May 29. Paris. 
 
 — June 27. Parma. 
 
 — July 5, 22, 23. Parma. 
 
 — Aug. 8. Ghent.— 19th. Prague. 
 
 • — Sep. 21. Parma; Brussels, Ghent, Groninguen, Fra- 
 neeker ; Cracow. 
 
 — Oct. 9. Parma.— 18th. Franckfort-on-Mein. — 19th. 
 
 Parma. — 21st. Paris. — 22nd. Parma. — 
 29th. Parma; Brussels. 
 ~ Nov. 7. Greenwich.— 12th. Paris.— 14th, 24th, 28th. 
 Parma. 
 
 — Dec. 11. Brussels. — 14th. England. — 21st. Brussels, 
 
 Ghent, Groninguen, Franecker ; Eutin ; 
 Cracow. — 24th, 28th. Parma. 
 
 1841. Jan. 8. Greenwich.- — 24th. Brussels. Two auroras 
 
 were seen this month at Eutin ; dates not 
 given. 
 
 — Feb. 24. Brussels. 
 
 — Mar. 10. Greenwich. — 22nd. Greenwich, Durham, 
 
 York, Belfast, England. 
 
 — April 12. Greenwich. — 15th. Prague. 
 
 — June 15, 16, 21. Brussels. 
 
 — Aug. 2. Prague.— 10th. Parma.: — 23rd. Brussels. 
 
 — Sept. 10. Paris, Prague.— 12th, 18th. Prague.— 23rd. 
 
 Brussels. — 25th. Parma, Brussels. 
 
 — Oct. 14. Prague.— 18th. Geneva. — 25th. Prague. 
 
 — Nov. 11. Paris.— 15th. Prague.— 18th, 19th. Brussels. 
 
 — Dec. 1. Genoa, Prague. — 6th, 8th. Greenwich, Cam- 
 
230 THE POLAE AtmORA, 
 
 bridge.— 12th. Paris.— 15th. Prague.— 
 19th, 20th. Cracow.- 24th. Prague. 
 
 1842. 
 
 Jan. 2. 
 
 Parma. 
 
 — 
 
 Feb. 28. 
 
 (?) 
 
 — 
 
 Mar. 7. 
 
 Guastalla.— 10th. Greenwich. 
 
 — 
 
 June 11. 
 
 Genoa. — 30th. Brussels. 
 
 — 
 
 July 3. 
 
 Brussels. 
 
 — 
 
 Sept. 6. 
 
 Gratz. 
 
 — 
 
 Oct. 7. 
 
 MontpelUer. — 16th. Parma. — 17th. Geneva. — 
 18th. Brussels, Geneva. 
 
 — 
 
 Nov. 4. 
 
 France.— 19th. (?).— 24th. Paris. 
 
 1843. 
 
 . Jan. 2. 
 
 Hamburg. 
 
 — . 
 
 Mar. 2, 
 
 8. Hamburg. — 13th. Parma. — 22nd. Brussels. 
 
 — 
 
 April 5. 
 
 Ghent, Hamburg. — 6th. Brussels. 
 
 — 
 
 May 6. 
 
 Paris, Rheims, Dieppe; Greenwich, Colling- 
 wood ; Brussels. — 9th. Brussels. 
 
 — 
 
 Aug. 2. 
 
 Hamburg. 
 
 — 
 
 Deo. 8, 
 
 10, 12. Parma.— 29th. Paris. 
 
 1844. 
 
 , Jan. 12, 
 
 13, 19. Hamburg. 
 
 — 
 
 Feb. 20. 
 
 Hamburg. 
 
 — 
 
 April 17. 
 
 Hamburg. 
 
 — 
 
 June 24. 
 
 Paris (?). 
 
 — 
 
 Aug. 1. 
 
 "Whitehaven.— 9th. Hamburg.— 22nd (?). 
 
 — 
 
 Nov. 14. 
 
 Hamburg. 
 
 — 
 
 Dec. 8. 
 
 Parma. — 29th. Paris, Rheims. 
 
 1845, 
 
 , Jan. 6. 
 
 Nantes. — 10th. Hamburg. 
 
 — 
 
 Mar. 6. 
 
 Uhn. 
 
 — 
 
 April 25. 
 
 (?)• 
 
 — 
 
 July 6. 
 
 (■)• 
 
 
 Aug. 25. 
 
 Parma. — 29th. Huggate, BOk, near Dussel- 
 dorf. — 30th. Between Dusseldorf and 
 Cologne. 
 
 — 
 
 Sept. 1. 
 
 Drachenfels.— 24th, 25th, 26th. BUk. 
 
 — 
 
 Nov. 5. 
 
 Parma. 
 
 
 Dec. 8. 
 
 Nottingham, Manchester ; Eutin. — 4th. Am- 
 sterdam, Bonn. — 13th. Swansea. — 14th. 
 Bonn.— 29th. Rheuns. 
 
 1846, 
 
 , Jan. 4. 
 
 London. 
 
 — 
 
 Feb. 18. 
 
 Bonn. — 25th. Geneva. 
 
 — 
 
 Mar. 14. 
 
 Geneva. 
 
 — 
 
 Aug. 28. 
 
 Bonn. 
 
 
 Sept. 13. 
 
 Huggate. — 21st. Cambridge, Durham, Esk 
 near Durham, Bembridge, Isle of Wight. — 
 22nd. Paris, Rheims; Huggate; Bonn; 
 Breslau; Saatz (Bohemia). 
 
 — 
 
 Oct. 17. 
 
 Dublin. — 24th. Monteagle (Ireland). 
 
APPENDIX. 231 
 
 1846. Nov. 3. Paris.— nth, 13th. Bonn.— 17th. Kingston, 
 
 Bonn, Prague, Ukermark, Elberfield, Leipzig. 
 Many places in North Germany, and a few 
 in South Germany. — 18th. Brussels. — 21st. 
 Bonn. 
 
 — Dec. 11. Bonn, Eolandseok. — 13th. Bonn. — 16th. 
 
 Yorkshire ; Bonn. — 17th. Bonn. 
 
 1847. Jan. 13, 14, Bonn. 
 
 — Mar. 17. Eutin.— 19th. Greenwich, Hyde Vale, Cam- 
 
 bridge, Playford near Ipswich, Darlington, 
 Spalding, Wolverton, Norfolk ; Brussels, 
 Emden, Hamburg, Oldenburg, Leipzig. 
 
 — June 6. Brussels. 
 
 — Sept. 17. Paris. — 21st. Norwich, Esk near Durham. — 
 
 24th. North of Prance ; Greenwich, Shrop- 
 shire. — 26th. Carlisle. — 28th. Louviers. — 
 29th. Carlisle, Swansea, Westmoreland ; 
 Brussels. — 30th. Westmoreland. 
 
 — Oct. 3, 6, CarUsle. — 13th. Westmoreland. — 14th. 
 
 Bonn. — 17th. Basle ; Gastein. — 28rd. 
 Parma ; Brussels. — 24th. Cadiz, Spain ; 
 Parma ; Paris, Bourges, &c. ; Cambridge, 
 Durham, York, Swansea, Blackheath, Mont- 
 eagle, Oxford, Ipswich, Greenwich, London, 
 Ireland, &c. ; Brussels ; Mannheim ; Wur- 
 temberg ; Leipzig. — 25th. Rouen. — 27th. 
 Brighton, Cambridge, Oxford, and other parts 
 of England. — 28th. Cambridge. 
 
 — Nov. 1. Paris. — 2nd. Bonn. — 17th. MontpeUier, 
 
 Paris. — 18th. Brussels. — 19th. Bonn, 
 Leipzig. — 20th. (?). — 22nd. Leipzig.— 
 25th. Eouen. 
 
 — Deo. 8, 10, Bonn. — 16th. Baden, Wurtemberg. — 17th. 
 
 Madrid ; Pisa, Florence ; Toulouse, Mont- 
 peUier, Bordeaux, Grenoble, Bourg, Cirey, 
 Saint - Symphorien - en - Laye, Bourges, la 
 P^erte-sous-Jouarre, Goersdorfif, departement 
 de la Seine, Blangy, Havre, almost all Prance ; 
 Brussels, Amsterdam ; Basle, Neuch4tel ; 
 Boim, Kirchheim ; Karlsruhe ; Freuden- 
 staedt, HaUe, Calw, Stuttgart, Heilbronn, &o. ; 
 Botzen, Balingen, Dresden, Leipzig ; Eutin, 
 Koenigsberg. — 18th. Eutin. — 19th. Nurem- 
 berg ; Dresden ; Eutin. — 20th. Bonn ; 
 Eutin. — 31st. Leipzig. 
 
 1848. Jan. 11. Mannheim.— 16th. Greenwich. — 20th. Leip- 
 
232 THE POLAE AUEOEA. 
 
 zig.— 25th. Goersdorff (Upper Ehine).— 
 28th. Bonn ; Leipzig. 
 1848. Feb. 20. Greenwich, and great part of England.— 21st. 
 Milan; Bourg, Goersdorff; England; Zurich, 
 Basle ; Bonn ; Wurtemberg ; Seelau, Leit- 
 meritz, Purglitz, PUsen, Hohenelbe, Dresden, 
 Warza, Leipzig, Pegau, Lutzen, Merseburg, 
 Zeitz, &c. — 22nd. Parma; Greenwich, Dur- 
 ham ; Kremsmunster, Klagenfurt ; Leit- 
 meritz. Purglitz. — 24th. Atlantic, 53° 41' 
 lat. N., and 18° 45' long. W.— 25th. Leit- 
 meritz. — 27th. Montpelher. 
 
 — Mar. 7. Bonn. — 15th. Stonyhurst. — 19th. Green- 
 
 wich, Durham, England ; Bonn. — 20th. 
 
 Greenwich, Durham, Stonyhurst. — 21st. 
 England. — 28th. Leeds.— Slst. Greenwich, 
 Stonyhurst. 
 
 — April 2. Leipzig. — 3rd. Greenwich, England. — 5th. 
 
 Leipzig.^eth. Brussels, Aix-la-Chapelle. — 
 7th. Greenwich, England. — 17th. Green- 
 wich, Stone. — 29th. Greenwich, England ; 
 Leipzig and district. 
 
 — May 11. Greenwich. 
 
 — July 8. Atlantic, 52° 12' lat. N., and 8° 32' long. W.— 
 
 11th. England, Atlantic, 46° 16' lat. N. and 
 36° 26' long. W.— 24th. Parma. 
 
 — Aug. 19. Portsmouth. — 28th. England.— 30th. Parma. 
 
 — Sept. 4, 8, 18. England.— 23rd. Atlantic, 51° 16' ht. 
 
 N., and 12° 20' long. W.— 30th. Aix-la- 
 Ghapelle. 
 
 — Oct. 17. Stonyhurst ; Stubenbach ; Kremsmunster. 
 
 — 18th. Spain ; Greenwich, Cambridge, 
 Stonyhurst, &c., and many parts of England ; 
 Atlantic, 49° 4' lat. N. and 19° 10' long. W. ; 
 Frankfort sur-Mein ; Salzburg, Strakowitz, 
 Winterberg, Kremsmunster. — 19th. Green- 
 wich, Stonyhurst, various parts of England ; 
 Atlantic, 50° 16' lat. N., and 13° 20' long. W., 
 and 48° 35' N. lat., and 14° 2' W. long. ; Aix- 
 la-Chapelle, Bonn ; Cracow. — 20th. Green- 
 wich, Stonyhurst, and other parts of Eng- 
 land. — 22nd. Greenwich, England; Brussels. 
 Aix-la-ChapeUe, Bonn; Stubenbach. — 23rd; 
 Montpellier; Atlantic, lat. 49° N., and 14° 
 long.W.; Brussels; Haltimer (near Namur); 
 Aix-la-Chapelle, Bonn ; Ittersdorf (Lake of 
 
APPENDIX. 233 
 
 Constance); Leipzig. — 24th. Parma; Paris; 
 Greenwich, England; Brussels; Aix-la- 
 Chapelle, Bonn. — 25th. Greenwich, Eng- 
 land ; Brussels ; Aix-la-Chapelle ; Bonn. — 
 26th. Brussels ; Aix-la-ChapeUe ; Bonn. — 
 27th. Greenwich, Prestwich, England. — 
 28th. Bonn.— 29th. Bonn; Leipzig.— 30th. 
 Greenwich, England. — 31st. Kremsmunstor. 
 
 1848. Nov. 5, 6. Parma.— 13th. Greenwich.— 14th. Green- 
 
 wich, England. — 17th. Smyrna, Salonica ; 
 Odessa ; Madrid, Spain ; Eome, Florence, 
 Pisa, Parma, Venice, Milan ; Montpellier, 
 Grenoble, Saint-Laurent-du-Pont, Bordeaux, 
 Toulouse, Eodez, Bourg, Cirey, Paris, Havre, 
 Dieppe, &c. ; Greenwich, Stonyhurst, Cam- 
 bridge, Liverpool, Manchfister, Durham, &c. ; 
 Bruges, and other places in Belgium ; Zurich, 
 Basle ; Aix-la-Chapelle ; Kassel ; Stuttgart 
 and other places in Wurtemberg ; Krems- 
 munster, Freistadt, Leitmeritz, Schoessel, 
 Strakowitz, Seelau ; Hohenelbe, Prague ; 
 Stubenbach ; Dresden, Leipzig ; BerUn. — 
 18th. Greenwich, Prestwich, and other parts 
 of England ; Brussels ; Aix-la-ChapeUe.^ 
 19th. Atlantic, lat. 50° 11' N., and 15° 30' 
 W. ; Geneva ; Bonn. — 21st. Parma ; France ; 
 Greenwich, Prestwich, and many parts of 
 England ; Brussels ; Aix-la-ChapeUe, Bonn ; 
 Leitmeritz ; Cracow. — 22nd. Leitmeritz. — 
 23rd. Greenwich, England. — 24th. Parma ; 
 Greenwich, England. — 25th, 26th. Green- 
 wich, England. — 28th. Stubenbach. — 30th. 
 Greenwich, England. 
 
 — Dec. 10. Greenwich. — 13th. Greenwich, England ; 
 
 Brussels ; Aix-la-ChapeUe. — 17th. Parma ; 
 Prestwich; Basle; Kremsmunster ; Gottin- 
 gen; Leipzig. — 21st. Atlantic, lat. 54° 8' 
 N., and 26° 10' W.— 22nd, 27th, 29th. Green- 
 wich, England. 
 
 1849. Jan. 1, 3. (?).— 4th. Prestwich.— 9th, 12th, 18th. (?)— 
 
 14th. Paris ; Prestwich, Whitehaven, 
 Aylesbury, Maidenstone Hall. — 15th. Hart- 
 well. — 22nd. Parma. — 27th. Smecna (Aus- 
 tria.) 
 
 — Feb. 18. Whitehaven, Wakefield.— 19th. Prestwich, 
 
 Stone, Whitehaven, Wakefield; Atlantic, 
 
234 IHE POLAH AUROEA. 
 
 lat. 50° 43'N. and 33° 20' W. ; Basle ; Leipzig, 
 — 20th. Greenwich, "Whitehaven, Hart- 
 well ; Atlantic, lat. 50° 16' N. and 14° 20' W. ; 
 Leipzig. — 21st. Hartwell ; Leipzig. — 22nd. 
 Parma ; Montpellier ; Greenwich, Oxford, 
 Holkham, Anglesbury, Stone, Norwich, 
 Newcastle ; Brussels, Waremme, Liege ; 
 Borni ; Basle ; XJlm. — 28rd. Whitehaven, 
 Hartwell; Bonn.— 24th, 25th. Bonn.— 
 26th. Aix-la-ChapeUe. — 27th. Montpelier; 
 Greenwich ; Brussels ; Aix - la - ChapeUe, 
 Bonn, Pegau ; Mergentheim, and other 
 parts of Wurtemberg ; Pilsen. 
 
 1849. Mar. 16, 17. Aix-la-ChapeUe.— 18th. Stone. 
 
 — May 13. Atlantic,5]°15'N.andl5°20'W.— 31st. Stone. 
 
 — June 15. Stone. — 26th, 30th. Latimer. 
 
 — Aug. 11. Parma.— 18th. Whitehaven.— 29th. (?). 
 
 — Sept. 3. Latimer. — 16th. Stonyhurst. — 27th. Bonn; 
 
 Breslau. 
 
 — Oct. 1. Whitehaven. — 15th. Cambridge, Stonyhurst. 
 
 21st. Aix-la-ChapeUe. — 22nd. Greenwich, 
 Carlington ; Aix-la-ChapeUe, Bonn ; Mer- 
 gentheim ; Winterberg, Juterbogk ; Leipzig. 
 — 23rd. Bonn. — 24th. Bruxelles, Bonn. 
 
 — Nov. 5. Bonn ; Senftenberg. — 9th. BruxeUes. 19th. 
 
 Boim. — 24th. Senftenberg. 
 
 — Dec. 14. Berne. 
 
 1850. Jan. 5. Greenwich. — 19th. Atlantic, lat. 50° N. and 
 
 26° 20' W.— 30th. HartweU.— 31st. Atlantic, 
 on the route between Liverpool and New 
 York. 
 
 — Feb. 3. Atlantic, lat. 53° 30' N. and 35° 20' W.— 6th. 
 
 Whitehaven, Stonyhurst, Durham. — 9th. 
 Manchester. — 10th. Stone. — 11th. Aix- 
 la Ghapelle. — 12th. Durham. — 18th. Aix- 
 la-ChapeUe. — 23rd. Parma; Senftenberg. 
 
 — Mar. 9. Whitehaven.— 10th. Nottingham, Stony- 
 
 hurst. — 11th. Greenwich, Stonyhurst.— r 
 27th. Bose Hill near Oxford. — 28th. 
 Stone. — 29th. Stone, Leeds. 
 
 — April 5. Whitehaven. — 6th. Durham.— 26th. Senf- 
 
 tenberg. 
 
 — May 12. Oxford, Aylesbury, Stonyhurst, Durham; 
 
 Senftenberg. 
 
 — June 4. Beigern near Briinn. — 5th. Nottingham, 
 
 Highfield House.— 13th. Oxford, Hartwell 
 
APPENDIX. 235 
 
 House, Rose Hill near Oxford ; Bonn. — 
 26th. Manchester.— 27tli. Nottingham, 
 Chesterfield. 
 
 1850. July 5. Norwich. — 12th. Norwich, Nottingham. — 
 
 27th. Atlantic, lat. 51° N. and 19°' W.— 
 28th. Atlantic, lat. 52° N. and 16° W. 
 
 — Aug. 6, 21. Stone. 
 
 — Sept. 6, 10. Nottingham. — 13th. Nottingham, Haw- 
 
 arden ; Hamburg. — 14th. Stone. — 18th. 
 Parma, Hartwell, Stone. 
 
 — Oct, 1. Greenwich, Cambridge, Saint-Ives, Hunts, 
 
 Stone, Grantham, Liverpool, Manchester, 
 Durham, Whitehaven, &c. ; Hamburg. — 
 2nd. Ostend, Namur, Aix-la-ChapeUe, 
 Bonn ; Hambiurg. — 3rd. Hamburg. — 5th. 
 Eose Hill near Oxford.— 8th, 9th. Holi- 
 ham. — 10th. Ebae Hill. — 15th. Manches- 
 ter.— 29th. Stonyhurst, North Shields. 
 
 — Nov. 2. Midhurst.— 3rd, 4th. Eose HiU.— 9th, 10th. 
 
 Jersey.— 12th. Holkham.— 14th, 15th, 16th. 
 Parma. — 21st. Cambridge. 
 
 — Dec. 23, 26. Holkham.— 27th. Hartwell, Midhurst, 
 
 Holkham, Whitehaven. 
 
 1851. Jan. 1, 5. Hawarden. — 9th. Highfield House near Not- 
 
 tingham. — 24th. Stonyhurst. 
 
 — Feb. 1. Eose Hill, Stonyhurst, Highfield House.— 
 
 2nd. Bonn. — 5th. Durham, North Shields, 
 Atlantic, lat. 49° N. and 24° W.— 6th. Eose 
 Hill.— 7th. Stone.— 8th. Atlantic, 51° N. 
 and 31° W.— 10th. Atlantic, lat. 51° N. 
 and 30° W.— 11th. Jersey.- 18th. Grant- 
 ham, Stone ; Basle. — 19th. Hawarden, 
 Durham. — 20th. Hawarden. — 23rd. Dur- 
 ham. — 24th. Hawarden. 
 
 — Mar. 7. Stone, Hartwell Eectory. — 8th. Stone.— 10th. 
 
 North Shields.— 14th. Durham.— 18th. 
 Hartwell. 
 
 — April 7. Leeds. — 18th. Nottingham. — 21st. Hawarden, 
 
 Grantham. 
 
 — May 15. Whitehaven. 
 
 — June 19, 20. Nottingham. 
 
 — Aug. 10. (?).— 13th, 14th. Stone.— 21st. Nottingham. 
 
 — 24th. Hawarden, North Shields ; Leip- 
 zig; Cracow. — 29th. Atlantic, par 51° N. 
 and 13° W.— 30th. Stonyhurst, White- 
 haven. 
 
236 THE POLAB AUEOEA. 
 
 1851. Sept. 4. Kew. — 6th. Durham, Whitehaven. — 7th, 
 
 Whitehaven. — 14th. Hartwell Eeotory, 
 Whitehaven. — iSth. Stone, Hartwell Eeo- 
 tory, Nottingham, Gainsborough, Stony- 
 hnrst, Harpham, Whitehaven, Durham, 
 Yorkshire.— 22nd, 24th, 26th. Aix-la-Cha- 
 pelle (traces). — 27th. Hawarden, Durham. — 
 28th. Norwich, Harpham, Durham.— 29th. 
 Cardington, Hartwell Bectory, Hartwell 
 House, Maidenstone HUl, Stone, Netting- 
 ham, Wakefield, Durham, North Shields ; 
 Purglitz ; Calw, Stuttgart, Boeblingen, 
 Vaihingen. — 30th. Nottingham, Yorkshire j 
 Prague ; Camenz, Neunkirchen, Leipzig. 
 
 — Oct. 2. Maidenstone HOI, Oxford, Cardington, Nor- 
 
 wich, Nottingham, Stonyhurst, Whitehaven, 
 Durham, North Shields, Yorkshire ; Brux- 
 elles, Namur, Ostend ; Aix-la-Chapelle, 
 Bonn ; Senftenherg, Dresden, Neunkirchen, 
 Varsovie. — Srd. Cardington, Nottingham, 
 Aix-la-Chapelle. — 4th. Nottingham, Dur- 
 ham. — 13th. Audieme (Finisterre). — 14th, 
 15th. Stonyhurst. — 18th. Durham, Bonn. 
 —28th. Wakefield, Stonyhurst, Durham, 
 Whitehaven, North Shields.— 29th. Hart- 
 well Eectory, Nottingham, Wakefield. 
 
 — Nov. 4. Aylesbury, Nottingham. — 5th, 6th, 13th. 
 
 Stonyhurst. — 17th. Verden sur I'Aller. — 
 20th. Aylesbury ; Verden. — 21st. Ayles- 
 bury.— 26th. Stonyhurst.— 30th. Verden. 
 
 — Deo. 6. Wakefield, Durham, Hawarden, Liverpool, 
 
 North Shields.— 8th. Hawarden. — 13th. 
 Aix-la-Chapelle. — 18th, 21st. Verden. — 
 22nd. Stonyhurst, Whitehaven, Notting- 
 ham, Hawarden, Durham, North Shields. — 
 23rd. Whitehaven.— 25th. Verden.— 28th. 
 Grantham ; Gembloux, near Namur. — 29th. 
 North Shields, Grantham, Stonyhurst. — 
 31st. Osnabruok. 
 
 1852. Jan. 2. Cracow.— Srd. Verden.— 4th. North Shields. 
 
 — 17th. Durham. — 19th. Bonn, Saar- 
 bruck, Birkenfeld, Elberfeld; Berne; Ver- 
 den; Leipzig. — 20th. Falmouth; Atlantic, 
 lat. 49° N. and 11° W.— 21st. Aylesbury, 
 Durham. — 22nd. Hartwell Eectory.— 23rd. 
 Oxford, Hatton, Hartwell Eeotory, Carding- 
 
APPENDIX. 237 
 
 ton, Grantham, Gainsborough, Hawarden, 
 Durham. — 25th. Durham, Hawarden, Man- 
 chester, Stonyhurst ; Verden. — 30th.- Eose 
 Hill, Thame, North Shields. 
 1852. Feb. 4. Highfield House.— 15th. Greenwich, all Eng- 
 land between Sl° and 55° N.— 16th. Green- 
 wich. — 17th. Greenwich, Durham, High- 
 field House, North Shields. — 18th. Green- 
 wich, all England between 50° and 57° 
 N. ; Salzhausen ; Breslau, Verden. — 19th. 
 All England between 49° and 57° N. ; Bonn ; 
 Berne ; Heilbronn, Calw ; Husum ; Eutin ; 
 Altona ; Vienna ; many parts of Germany ; 
 Preny (Poland.) — 20th. Greenwich ; Hel- 
 ston, Norwich ; Atlantic, lat. 51° N. 
 and 17° W. ; Holitsch, Vienna ; Cracow ; 
 Verden. — 21st. Whitehaven, Durham, 
 Gainsborough, Wakefield, Stonyhurst, Hel- 
 Bton, Grantham, Highfield House, Glasgow. 
 —22nd. Highfield House ; Verden.— 23rd. 
 Stonyhurst, Durham.— 25th, 26th. High- 
 field House. — 27th. Durham, North Shields. 
 —28th. Aylesbury. 
 
 — Mar. 2, 5. Highfield House.— 12th, 15th. Verden.— 
 
 17th. Coast of Essex between Blaokwater 
 and Crouch Eiver. — 20th. Stonyhurst. — 
 21st. Hawarden, Saint-Ives. — 25th. Stony- 
 hurst. — 26th. Bonn ; Leipzig. — 28th. 
 Highfield House. — 31st. Stonyhurst. 
 
 — April 1. Atlantic, lat. 51° N. and 9° W.— 8th. Verden. 
 
 —9th, 11th. Stonyhurst.— 13th. Verden.— 
 14th. Glasgow.— 15th. Atlantic, lat. 47° 
 N. and 31° W.— 18th. Stonyhurst.- 20th. 
 Bose Hill.— 21st. Oxford, Highfield House. 
 —22nd, 23rd, 26th. Highfield House. 
 
 — May 1. Stone. — 2nd. Stone, HartweU Eectory. — 3rd. 
 
 Hartwell Eectory, Highfield. 
 
 — June 11. Greenwich.— 19th. Stone.— 24th. Highfield 
 
 House. 
 
 — July 3, 6. England.— 10th. Munster.— 13th, 14th. Eng- 
 
 land. 
 
 — Aug. 8. Atlantic, lat. 47° N. and 23° W.— 10th. Bonn ; 
 
 Munster, Verden. — 22nd. Laupen, near 
 Berne. 
 
 — Sept. 4. Parma— 11th. England.— 12th, 13th. Verden. 
 
 —17th. England; Verden.— 18th, 19th, 
 
238 THE POLAE AUEORA. 
 
 20th. England.— 2l8t. England; Verden. 
 —29th. Paris. 
 
 1852. Oct. 5. Stone.— 10th, 13th. Verden.— 18th. Stutt- 
 
 gart; Verden.— 23rd, 24th, 25th, 26th. 
 Stone. 
 
 — Nov. 3. Stone, Oxford, Nottingham, Liverpool. — 7th. 
 
 Hawarden. — 8th. Stonyhurst. — 10th. Er- 
 langen. — 11th. Alsace ; Lewisham, Green- 
 wich; Basle, Lausanne, Coire, Grisons; 
 Platinate ; Karlsruhe, Mannheim, Stuttgart 
 and all "Wurtemberg; Salzburg, Vienna; 
 Neunkirchen, Erlangen, Odenwald, Salz- 
 hausen ; Breslau. — 12th. Linz ; Cracow. — 
 13th. Brunn.— 17th. Senftenberg.— 18th. 
 Stone. — 80th. Liverpool. 
 
 — Deo. 6. Erlangen ; Vienna. — 8th. Erlangen.— 9th. 
 
 Bose Hill.— 12th. Stone.— 14th. Erlangen.' 
 — 15th. Grantham. — 18th. Parma. — 20th. 
 Stone. 
 
 1853. Jan. 2. Paris. — 4th, 5th. Hawarden.— 7th. Clifton, 
 
 Bose HUl, Stonyhurst; Erlangen. — 8th. 
 Stonyhurst.— 12th. Erlangen.— 15th. Clif- 
 ton. — 31st. Durham, Grantham. 
 
 — Feb. 44. Whitehaven.— 15th. Nottingham.— 16th, 17th. 
 
 North Shields.— 23rd. Nottingham.— 27th. 
 Nottingham, Hawarden, Stonyhurst, WTiite- 
 haven. — 28th. Stone, HartweU Eectory. 
 
 — Mar. 7. Midhurst, Clifton, Hawarden, Durham ; Atlan- 
 
 tic, lat. 51° N. and 21° W.— 8th. CUfton, 
 Stonyhurst, Durham. — 17th. Stone, Bices- 
 ter, HartweU Eectory. — 21st. Holkham. — 
 29th. Stone. 
 
 — April 5. Greenwich, Stone, HartweU House ; Atlantic, 
 
 50° N. and 80° W. ; Munster.— 6th. Ha- 
 warden, Darlen. — 7th. Stone, HartweU 
 Eectory, Hawarden. — 8th. Hawarden, 
 Stonyhurst, Durham. — 24th. Hawarden. 
 
 — May 4. Hawarden, North Shields. — 14th. Manchester. 
 
 — 24th. Nottingham. 
 
 — June 22. Greenwich. 
 
 — July 2. Venice ; Biel (Hesse-Nassau). — 12th. Ha- 
 
 warden; Vienna. 
 
 — Aug. 20, 26, 80. Hawarden. 
 
 — Sept. 1. Greenwich. — 2nd. Greenwich, Exeter, CUfton, 
 
 Warrington, Liverpool, Manchester, York 
 Cambridge, Durham, Hawarden, Makree, 
 
APPENDIX. 239 
 
 Dublin ; Prague ; Hamburg, Angela. — 3rd. 
 Clifton.— 28th, SOtli. Durham. 
 
 1853. Oct 17. Durham. — 25th. Nottingham, Durham.— 
 
 29th. 'Whitehaven.— 30th. Paris (?).— 31st. 
 Cherbourg ; AmpthiU (Bedfordshire) and 
 many parts of England ; Munster ; Koenigs- 
 berg. 
 
 — Nov. 1. Oxford; Munster. — 2nd. Whitehaven. — 7th. 
 
 Leipzig. — 8th. Isle of Man, Durham, 
 North Shields.— 9th. Nottingham.— 10th. 
 Leipzig. — 22nd. North Shields, Isle of 
 Man, Durham, Stone, Stonyhurst ; Leipzig. 
 —30th. Weischlitz. 
 
 — Dec. 5. Helston, Nottingham. — 6th. Durham, Truro, 
 
 Clifton, Lewisham, Greenwich, Stonyhurst, 
 Isle of Man, "Whitehaven, North Shields. — 
 8th. Durham.— 23rd. Greenwich. — 24th. 
 Clifton ; Senftenberg. — 25th. Senftenberg. — 
 26th. Falmouth; Senftenberg.— 27th. Fal- 
 mouth. — 28th. Warrington. — 29th. Jersey ; 
 Clifton.— 30th. Jersey. 
 
 1854. Jan. 2. Eome : Kcenigsberg. — 31st. Greenwich. 
 
 — Feb. 10. Parma. — 26th. Greenwich. 
 
 — April 13. Greenwich ; Xanten am Ehin; Munster; Ham- 
 
 burg. 
 
 — June 24. Parma. 
 
 — July 15. Senftenberg. 
 
 — Sept. 14. Clays, near Amiens.— 26th. Paris. 
 
 — Oct. 15. (?). 
 
 1855. Mar. 17. Berne. 
 
 — May 20 (?). 
 
 — Oct. 16, 18. Greenwich. 
 
 — Dec. 3. Atlantic, lat. 49° N. and 44° W. 
 
 1856. Feb. 1. Glarus (?), perhaps the zodiacal light. — 3rd. 
 
 Munster. 
 
 — Mar. 12. Senftenberg. 
 
 — June 2, 3, 4. Paris. 
 — ■ Dec. 8. Hanau. 
 
 1857. Nov. 22. Klosters (Switzerland). 
 
 — • Dec. 17. Brussels ; Bretten, Bruchsal, and aU the West 
 of Wurtemberg. 
 
 1858. Mar. 9. Bonn; Putbus, Altona. — 11th. Bonn. — 13th. 
 
 Oxford. — 14th. Oxford, Armagh. 
 
 — April 1. Bose Hill. — 9th. Munster ; Gottingen ; Nau- 
 
 gard ; Senftenberg, Dresden ; Breslau. — 10th. 
 Oxford, and many parts of England. — 11th- 
 
240 THE POLAR AUEOEA. 
 
 Clifton.— 12th. SiUoth; Munster.— 21st. 
 Paris.— 24th. Fairlight.— 29 th. Clifton. 
 
 1858. May 2, 6. Clifton.— 7th. Oxford, Clifton.— 8th, 10th. 
 
 Clifton. 
 
 — June 6. Oxford. 
 
 — Deo. 4. South of France ; Wurtemberg, Munster, Halle, 
 
 and other parts of Germany ; Prague, Jung- 
 bunzlau ; Kremsmunster, Gaedonek, near 
 Goch, — 31st. Havre. 
 
 1859. Jan. 22. Helston.— 23rd. Bose HiU.— 29th, 30th, 31st. 
 
 Athens. 
 
 — Feb. 2. Athens. — 9th. Many parts of England. — 11th, 
 
 12th, 14th. (?).— 18th, 19th. Naugard.— 
 22nd. Oxford, and many parts of England. 
 — 23rd. Oxford, and many parts of England ; 
 Prague; Munster; Naugard, Saalz, Ham- 
 burg, Eendsburg. — 24th. Oxford and many 
 parts of England; Naugard. — 25th. Notting- 
 ham, Stonyhurst. — 26th. Clifton ; Munich. 
 
 — Mar. 2. Rose Hill. — 25th. Saint-Paul's Parsonage. — 
 
 26th. Oxford and many parts of England. — 
 27th. Nottingham, Hawarden. — 29th. Ha- 
 warden. — 30th. Many parts of England.^ 
 31st. Saint-Paul's Parsonage. 
 
 — April 1. Eng'and. — 7th. Paris. — 14th. Armagh. — 21st. 
 
 MontpeUier, Paris ; Greenwich ; Brussels ; 
 Vienna, Kremsmunster ; Cracow, Prague ; 
 Munich, Bamberg; HaUe, Dessau, Hoefgen 
 near Grimma; Dresden, Oberwiesenthal, 
 Leipzig ; Berlin ; Breslau. — 22nd. Brussels ; 
 Munster, Gaesdonk. — 23rd. Kremsmunster ; 
 Munster. — 28th. England.— 29th. Laer 
 (Westphalie) ; Kremsmunster. 
 
 — May 1, 5. England. — 31st. Athens. 
 
 — July 15. Wewelinghofen (Bhenish Prussia). 
 
 — Aug. 2. (?). — 28th. Athens; Kome, Parma; Mont 
 
 pellier, Lyons, Paris, Saint- Valery ; Noy 
 eUes-sur-Mer ; London, Brighton, Clif' 
 ton, and all England ; Atlantic, lat. 26° N, 
 and 29° W., and lat. 51° N. and 13° W. 
 Brussels ; all Holland ; Geneva, Basle, Eafz, 
 Neuch&tel; Ittendorf (lake of Constance) 
 Schemnitz (Hungary) ; Vienna, Olmutz, 
 Prague; Bodenbach, Schossle, Bamberg, 
 Neunkirchen, Stuttgart; Leipzig, Saxony, 
 &c., and in general all Germany. — 29th, 
 
APPENDIX. 241 
 
 Dunkirk; Prague.— 30th, 31st. Grant- 
 ham ; Visehel near Altenahr. 
 
 1859. Sept. 1. Grantham; Prague; Cracow. — 2nd. Athens; 
 
 Eome ; Clifton, Durham ; Kremsmunster ; 
 Cracow. — 3rd. Athens; Clifton, Durham; 
 Kremsmunster ; Cracow ; Hamburg and 
 all Northern Germany ; Kosnigsberg, Cranz, 
 near Kosnigsberg. — 4th. Tottenham, Clifton, 
 Durham, Grantham, Newmark. — 5th. Nau- 
 gard. — 6th. Munster ; Hamburg, Naugard. 
 — 24th. Venice; Greenwich, South of Eng- 
 land ; Holland ; Kremsmunster ; Prague ; 
 Wurtemberg ; Cologne, Crefeld, Hulsen near 
 Crefeld, Munster, Hamm, Elberfeld ; Soest, 
 Lippstadt, Heiligenstadt. — 25th. Munster. 
 —27th. Hamburg. 
 
 — Oct. 1. Toulouse, Lyon, Yzeure (Allier), Bois des 
 
 Fosses, Paris ; Greenwich, Limerick, South 
 coast of England ; Basle ; Prague ; Kreuz- 
 naoh ; Kremsraunster ; Sankt - "Wendel, 
 Munich ; Naugard, Munster, Gaesdonck, 
 Hamburg; Anspach. — 2nd. Madrid; Cas- 
 tera near Toulouse ; Prague ; Kassel. — 10th. 
 Amiens. — 12th. Athens ; Naples, Eome ; 
 MontpeUier, Lyons, Yzeure, la Chaux-de- 
 Fonds, Saint-Am6 (Vosges),Eouen, Amiens ; 
 Southampton, Greenwich, Oxford; Luxem- 
 burg, Brussels, Namur; Berne, Neuch^tel; 
 Frankfort- on- the-Main, Kremsmunster ; 
 Cracow ; Wurtemberg ; Kassel ; Dresden, 
 Leipzig ; Putbus ; Berlin, Lichtenberg, near 
 Berhn, Hervest, near Dorsten, Naugard, 
 Stettin.— 13th, 14th. Naugard.— 15th. La 
 Turbie, near Monaco. — 17th. Paris; Green- 
 wich, Oxford. — 18th. Athens ; Vienna. — 
 19th. Paris; Greenwich. — 23rd. Eeutlingen. 
 —24th. Atlantic, lat. 47° N. and 15° W. ; 
 Peckeloh. 
 
 — Deo. 6. Eome. — 13th. Oxford ; Naugard. — 21st. 
 
 Gresten (Austria). 
 
 1860. Jan. 1. Louvain. 
 
 — Feb. 12. Nottingham; Peckeloh. — 23rd. Leipzig. 
 
 — Mar. 12, 18, 22, 25. Nottingham.— 26th. Dresden. 
 
 — April 9. Paris ; Greenwich, Nottingham ; Brussels ; 
 
 Wurtemberg, Munster, all Westphalia, Kre- 
 feld, Hamm, Wiedenbruck, Hamburg. — 
 17 
 
242 THE POLAB AUEOEA. 
 
 10th. Paris.— 12th. Paris; Hamburg.— 
 ISth. Hamburg. — 16th. Nottingham ; 
 Munster. 
 
 1860. May 9. Oxfotd. 
 
 — Aug. 7. Clermont-Ferrand; Vienna; Prague; Berlin. 
 
 — 8th. Athens ; Clermont-Ferrand ; Munich, 
 Naugard. — 9th. Athens ; Paris ; Brussels ; 
 Kremsmunster ; Prague; Dresden, Brauns- 
 berg; Emden, Naugard, Liohtenberg near 
 BerUn, Lauenburg (Pomerania). — 10th. 
 Athens ; Nantes, Paris ; Brussels ; Nor- 
 derney ; Dresden. — 11th. Athens ; Paris ; 
 Prague ; Peckeloh.— 12th. Athens ; Paris ; 
 Yverdon ; Kremsmunster, Vienna. — 13th. 
 Athens ; Emden, Westphalia. — 14th. Athens. 
 —25th. Athens; Oelde (Westphalia).— 27th. 
 Westphalia.— 80th. Gouda (Holland). 
 
 — Sept. 6. Utrecht ; Leipzig ; Peckeloh. — 7th. Paris ; 
 
 Utrecht.— 8th. Peckeloh. 
 
 — Oct. 1. Kreuznach. — 19th. Putbus. 
 
 — Nov. 2. Nottingham. 
 
 — Dec. 8. Munster; Peckeloh. 
 
 1861. Jan. 24. Le Lochle ; Munster, Peckeloh, Coesfeld, 
 
 Elberfeld, Gaesdonck. 
 
 — Feb. 12. Prague. — 27th. Greenwich; Prague. 
 
 — Mar. 1. Oxford. — ^2nd. Groninguen ; Peckeloh. — 4th. 
 
 Athens. — 8th. Munster. — 9th. Montpellier, 
 Paris ; Greenwich, Oxford ; Brussels, 
 Louvain, Nimeguen, Flushing, Delle, Ooster- 
 huizen, Workum, Utrecht, Slijk-Ewijk ; 
 Geneva, NeuehS.tel, Avenches, Saint-Aubin, 
 Lucerne ; Kremsmunster ; Prague, Gitschin, 
 Koeniggroetz ; Saarbruck, Elsfleth, Gaes- 
 donck, Munster, Mannheim ; Wurtemberg ; 
 Peckeloh, Ehine, Berlin, Neumarck, Loebau, 
 Liibeck, Putbus, Dessau ; Cracow. — 19th. 
 Gitschin. — 25th. Prague. 
 
 — April 7. Oxford ; Slijk-Bwijk. — 15th. Slijk-Eyrijk, 
 
 Workum ; Munster, Peckeloh ; Berlin. — 
 24th. Munster.— 25th, 28th, 29th. Prague. 
 
 — Aug. 12. Yverdon. 
 
 — Sept. 11. Munster. — 25th. Workum. 
 
 — Oct. 2. Utrecht.— 10th. Brussels, Utrecht ; Peckeloh. 
 
 — 12th. Greenwich. 
 Nov. 3. Liohtenberg, near Berlin. — 5th. Peckeloh. — 
 
APPENDIX. 243 
 
 7th. Oxford ; Ouddorp ; Peckeloh, Liehten- 
 berg, Ebstorf, Naugard. — 24th. Oxford. 
 
 1861. Dec. 2. Prague ; Dessau. — 3rd. Peckeloh. — 4th. 
 
 Greenwich ; Delle, Workum, Helder, Noord 
 Hinder near Gaesdonck, Peckeloh, Naugard; 
 Carrow near Mecklenberg. — 19th. Dresden. 
 —20th. Basle.— 23rd, 24th. Dresden.— 
 26th. Dresden, Peckeloh. 
 
 1862. Jan. 17. Lichtenberg. — 18th. Peckeloh; Lichtenberg. 
 
 —22nd, 23rd, 26th. Lichtenberg. 
 
 — Feb. 8. Lichtenberg, Peckeloh. — 18th. Peckeloh.— 
 
 21st. Workum, Ouddorp, Helder, Noord- 
 Hinder ; Munster, Gaesdonk, Peckeloh. — 
 22nd. Athens.— 27th. Peckeloh. 
 
 — Mar. 1. Lichtenberg, Peckeloh. — 3rd. Peckeloh. — 4th. 
 
 Munster; Peckeloh.— 5th, 8th, 13th. Pecke- 
 loh.— 14th. Athens.— 24th, 25th, 27th, 28th, 
 29th. Lichtenberg. 
 
 — April 2, 3. Peckeloh.- 13th. Paris. 
 
 — May 1. Milan; Peckeloh. — 2nd. Peckeloh. — 3rd. 
 
 Milan. — 18th. Wilna. — 19th. Milan ; 
 Munster; Wilna.— 20th. Milan; Wihia. 
 
 — June 4. Noord-Hinder. — 5th. Brouwershaven. 
 
 — July 19. Senftenberg (Bohemia). ^ — 26th. Peckeloh. — 
 
 27th. Milan ; Peckeloh, Leipzig.— 28th. 
 Peckeloh. — 29th. Leipzig. 
 
 — Aug. 4. Milan ; Paris ; Ootmarsum ; Munich ; Munster, 
 
 Peckeloh. — 19th. Noord-Hinder ; Peckeloh. 
 —20th. Peckeloh.— 21st. Milan.— 24th, 
 25th, 27th. Peckeloh. — 28th. Milan; 
 Senftenberg; Peckeloh; Naugard.— 29th. 
 
 r ftp. K fll On 
 
 — Sept. 2, 11, 13, 15, 16, 18. Peckeloh.— 24th. Senftenberg, 
 
 Naugard, Peckeloh.— 29th, 30th. Peckeloh. 
 
 — Oct. 6. Peckeloh.— 9th. Utrecht; Peckeloh.— 11th. 
 
 Montpellier.— 15th, 17th. Peckeloh.— 24th. 
 Worthmgton (?).— 28th, 31st. Peckeloh. 
 
 — Nov. 19, 29. Peckeloh. 
 
 — Dec. 4. Peckeloh. — 14th. Borne, Bologna, Bergamo, 
 
 Parenzo, Trieste; Marseilles, Montpelher, 
 Puychamaud (Dordogne), Limoges, Bellao, 
 Paris ; Greenwich, Queenstown ; Brussels, 
 Antwerp, Ghent, all Holland ; Geneva, 
 Neuohatel, Basle, Zurich, Ittendorf; Co- 
 blentz, Munster, Peckeloh; Wurtemberg; 
 
244 THE POLAK AUEORA. 
 
 Leipzig, Salzhausen, Liohtenberg. — 15th. 
 Horst (Holland). — 22nd. Lichtenberg. — 
 25th. Emden, Mannheim, Breslau. 
 18C3. Jan. 7, 9. Peckeloh.— 12th. Lyon.— 15th. Mannheim. 
 —25th. Noord-Hinder. 
 
 — Feb. 9. Berlin. — 10th. Mannheim. — 14th, 17th. 
 
 Peckeloh. — 22nd. Utrecht, Noord-Hinder ; 
 Ludingen (Hanover). 
 
 — Mar. 3, 4, 18, 21. Peckeloh. 
 
 — April 1, 7, 9, 10, 19. Peckeloh. 
 
 — May 1. Peckeloh. — 6th. Leeuwarden. — 9th. Peckeloh; 
 
 Cracow. 
 
 — June 22. Peckeloh.— 23rd. Noord-Hinder. 
 
 — Aug. 9. Mannheim. — 17th. Munster. 
 
 — Sept. 20. Peckeloh. 
 
 — Oct. 7, 8. Peckeloh.— 11th. Munster.— 25th. Peckeloh. 
 
 — Nov. 1, 2. Peckeloh. — 9th. Utrecht; Munster; Peckeloh. 
 
 — 10th. Lichtenberg. — 11th. Peckeloh ; 
 Lichtenberg.— 13th. Athens.— 18th, 20th. 
 Peckeloh. — 29th. Munster; Peckeloh. 
 
 — Deo. 4. Peckeloh. — 10th, 11th. Athens. — 14th. 
 
 Munster ; Dresden ; Peckeloh ; Berlin. — 
 18th. Peckeloh. 
 1864. Jan. 6, 14, 16, 17. Peckeloh. 
 
 — Feb. 1. Zurich.- 9th. Berlin.— 14th, 17th. Peckeloh. 
 
 — Mar. 6. Peckeloh.— 7th, 8th, 9th. Lichtenberg.— 10th. 
 
 Munster ; Naugard ; Peckeloh ; Berlin, 
 Lichtenberg. — 14th. Hanover. — 18th, 22nd, 
 25th. Peckeloh. 
 
 — April 2. Lichtenberg. — 5th. Munster; Peckeloh. — 8th. 
 
 Lichtenberg.— 16th, 20th. Peckeloh.— 27th. 
 Munster ; Naugard ; Peckeloh. — 30th. 
 Peckeloh. 
 
 — May 3. Peckeloh.— 9th. Cracow.— 12th. Peckeloh. 
 
 — June 12, 13. Peckeloh.— 18th. Lisbon. 
 
 — July 10. Zurich.- 12th, 28th. Peckeloh. 
 
 — Aug. 1, 2. Kephissia near Athens. — 5th. Peckeloh. — 
 
 6.th. Athens — 9th. Kephissia. — 17th. 
 Munster; Peckeloh.— 31st. Naugard. 
 
 — Sept. 13, 14. Peckeloh.— 25th. Peckeloh ; Aardenburg. 
 
 —27th, 29th. Peckeloh. 
 
 — Oct. 7. Westphalia. — 8th. Munster, Westphalia ; 
 
 Naugard ; Peckeloh. — 11th. Munster. — 
 15th. Lichtenberg.— 19th. Valentia (Ire- 
 land) ; Peckeloh ; Lichtenberg.— 2lBt. Paris. 
 —25th. Peckeloh. 
 
APPENDIX. 245 
 
 1864. Nov. 2, 7. Peckeloh.— 9th. Mimster; Peckeloh.— 23ra. 
 
 Peckeloh. — 29th. Munster ; Peckeloh. — 
 30th. JuUers. 
 
 — Deo. 11. Peckeloh.— 18th, 22nd. Lichtenberg.— 23rd. 
 
 Munster ; Peckeloh. — 24th. Frankenthal 
 (Rhenish Bavaria) ; Munster.— 29th, 30th, 
 31st. Liohtenberg. 
 
 1865. Jan. 6. Munster.— 9th. Borne.— 12th. Peckeloh.— 
 
 17th. Marseilles ; Munster ; Peckeloh ; 
 Lichtenberg.— 24th. Marseilles; Munster. 
 — 25th. Leeuwarden. — 27th. Paris. — 29th, 
 30th. Liohtenberg. 
 
 — Feb. 15. Peckeloh. — 17th. Greenwich ; Cork ; Munster ; 
 
 Peckeloh ; Lichtenberg. — 18th. Naugard ; 
 Liohtenberg. — 21st. Peckeloh. — 22nd. 
 Peckeloh ; Lichtenberg, — 23rd, 27th. Lich- 
 tenberg. 
 
 — Mar. 4. Peckeloh. — 7th. Gorcy near Metz. — 18th. 
 
 Bamberg ; Peckeloh. — 19th. Lichtenberg. 
 — 20th. Greenwich ; Munster ; Peckeloh ; 
 Naugard ; Liohtenburg. — 21st, 22nd. Bam- 
 berg; Lichtenberg.^23rd. Lichtenberg. 
 
 — April 8, 9, 16. Peckeloh.- 28th. Berne. 
 
 — June 17. Athens.— 28th. Peckeloh. 
 
 — July 18. Mimster.- 19th. Peckeloh. 
 
 — Aug. 2. Munster ; Peckeloh ; Sudenburg near Magde- 
 
 burg.— 13th, 14th. Peckeloh.— 18th. Leeu- 
 warden. — 19th. Mimster ; Papenburg. — 
 25th. Peckeloh.— 26th. Ostend; Munster; 
 Peckeloh; Papenburg. 
 
 — Sept. 16, 21, 22. Peckeloh.— 26th. Papenburg. 
 
 — Oct. 13, 14, 28, 31. Peckeloh. 
 
 — Nov. 7. Holder. — 8th. Vend6me ; Valentia. — 9th. 
 
 Papenburg. — 14th. Munster ; Peckeloh ; 
 Papenburg. 
 
 1866. Jan. 4. Peckeloh. — 6th, 12th. Lichtenberg. — 29th. 
 
 Peckeloh. 
 
 — Feb. 6. Peckeloh ; Liohtenberg. — 7th. North Shields, 
 
 By well ; Papenbui-g ; Liohtenberg. — 9th. 
 Peckeloh. — 12th. Greenwich; North Shields. 
 —13th. N. Shields.— 15th. Lichtenberg. 
 
 — Mar. 7. Peckeloh ; Papenburg ; Lichtenberg. — 8th. 
 
 Lichtenberg. — 14th. Peckeloh ; Liohtenberg. 
 — 15th. Lichtenberg. — 16th. Peckeloh. — 
 17th. Paris.— 20th. Peckeloh. 
 
 — April 8. Lichtenberg.— 9th, 23rd, 26th. Peckeloh. 
 
246 THE POLAR AUEOEA. 
 
 1866. May 14, 19. Peckeloh. 
 
 — June 13. Peckeloh. 
 
 — July 15. Peckeloh. 
 
 — Aug. 11. Peckeloh.— 14th. Atlantic, lat. 54° N. and 
 
 long 24° W. 
 
 — Sept. 2, 4, 8. Peckeloh. 
 
 — Oct. 1,2. Peckeloh; Lichtenberg. — 3rd. Munster; 
 
 Peckeloh ; Lichtenberg. — 4th. Peckeloh ; 
 Lichtenberg. — 5th. Munster; Lichtenberg. 
 — 6th. Lichtenberg.— 8th, 10th. Peckeloh. 
 —11th. Lichtenberg.— 14th, 22nd, 23rd, 
 25th. Peckeloh. 
 
 — Nov. 1. Munster; Peckeloh. — 4. Lichtenberg. — 10th. 
 
 Brussels; Munster. — 11th. North Shields, 
 Allenheads. — 12th. Lichtenberg. — 19th. 
 Allenheads.— 24th, 25th. Peckeloh.— 26th. 
 Peckeloh ; Hamburg ; Papenburg ; Lichten- 
 berg. — 27th. Lichtenberg. — 28th. Munster. 
 —29th. By weR ; Lichtenberg.— 30th. Lich- 
 tenberg. 
 
 — Deo. 8, 10. Lichtenberg. — 25th. Allenheads, Bywell. — 
 
 30th. Lichtenberg. 
 
 1867. Jan. 28. Marseilles; Platta (Switzerland). 
 
 — Mar. 21. Peckeloh. 
 
 — May 3. Peckeloh.— 4th. Pussen.— 17th. Tarifa.— 
 
 19th. Peckeloh.— 23rd. Neuchatel. (Swit- 
 zerland) (doubtful).— 25th. Peckeloh. 
 
 — June 12. Cracow. 
 
 — July a. Peckeloh. 
 
 — Aug. 26. Peckeloh. 
 
 — Sept. 12. Peckeloh.— 25th. Lichtenberg.— 26th. Pec- 
 
 keloh; Lichtenberg. 
 
 — Oct. 21, 22, 26. Lichtenberg.- 27th. Peckeloh.— 28th. 
 
 Peckeloh ; Lichtenberg. — 30th. Lichten- 
 berg. 
 
 — Nov. 2. Peckeloh.— 27th, 28th. Lichtenberg. 
 
 — Dec. 2. Lichtenberg. 
 
 1868. April 2. Peckeloh.— 20th. Ireland. 
 
 — May 20. Greenwich. 
 
 — Oct. 22. Munster; Peckeloh. 
 
 — Nov. 14. Peckeloh. — 19th. Munster; Peckeloh. 
 
 — Dec. 4, 12, 14. Lichtenberg. 
 
 1869. Jan. 7. Peckeloh.— 11th, 12th. Lichtenberg. 
 
 — Feb. 3. Greenwich; Naugard; Koeslin; Danzig; 
 
 Putbus. — 5th. Breslau. — 14th. Padua, 
 Moncalieri. 
 
APPENDIX, 247 
 
 1869. Mar. 6, 7, 12, 13, 31. Peckeloh. 
 
 — April 1, 2. Peckeloh.— 15th. Paris and the greater part 
 
 of France from south to north; London, 
 Greenwich, Liverpool; Brussels, Utrecht, 
 the whole of Holland; Zurich, Altorf, 
 Gersau, Eiasiedeln, AltstEetten, Saint- 
 Gall, Brienz ; Sankt-Gyorgyi (Hungary) ; 
 Chlumetz ; Munich ; Munster ; Peckeloh, 
 and many parts of Germany. — 16th. Green- 
 wich ; Danzig. — 17th. Liohtenberg. 
 
 — May 5. Peckeloh.— 8th. Borne.— 9th. Danzig. — 13th. 
 
 Azores ; Athens ; Bome, Leghorn, Venice, 
 Padua ; Trieste, Pola, Lesina, Zombor ; . 
 Paris and the north of Prance ; Greenwich, 
 tilanrwst, Shrewsbury, Manchester ; Brus- 
 sels ; Amsterdam, Workum, and the whole 
 of Holland; Splugen, San-Vittore, Sils 
 Maria, Groeohen, Vaudens, Einsiedeln, 
 Schwyz, Berne and all the north of Switzer- 
 land, Buda, Altenburg (Hungary) ; Vienna, 
 Baden near Vienna, Ischl, Goerz, Laibach, 
 Gratwein ; Cologne, Munster ; Hamburg ; 
 Munich ; Peckeloh, Berlin, Lichtenberg, 
 &c.— 14th, 15th. Paris.— 29th. Hungary. 
 
 — June 7. Peckeloh. — 29th. Greenwich. 
 
 — July 29. Zurich. 
 
 — Aug. 6. Zurich. — 10th. Athens. 
 
 — Sept. 3. Greenwich ; Lichtenberg. — 4th. Munster ; 
 
 Peckeloh. — 5th. Paris ; Danzig. — 11th. 
 Peckeloh ; Lichtenberg. — 22nd. Danzig. 
 —25th. Lichtenberg. — 27th, 28th, 29th. 
 Peckeloh. 
 
 — Oct. 1, 3, 5. Munster. — 6th. Paris ; London, Green- 
 
 wich; Brussels, Louvain; Aix-la-ChapeUe; 
 Munster; Flensburg, Keitum, Wolgast. 
 Schleswig. — 18th. Danzig. — 21st. Athens. 
 -^25th. Peckeloh; Posen. 
 
 — Nov. 3. Lichtenberg. — 10th. Altenburg. 
 
 — Dec. 7. Munster ; Peckeloh. — 11th. Hermannstadt. — 
 
 25th. Grullenberg (Saxony) ; Peckeloh. — 
 30th. Peckeloh. 
 
 1870. Jan. 1. Culloden ; Gratz, Meseritz, Beitzenhain. — 2nd. 
 
 Culloden. — 3rd. Volpeglino, Piedmont ; 
 Nantes, and other parts of France ; Guern- 
 sey ; Worthing, Eoyston, Somerleyton, 
 Norwich, Boston, Eccles, Cxilloden ; Brus- 
 
248 THE POLAR AURORA. 
 
 sels. — 4th. Wisbecli.— 6th. Munster ; 
 Papenburg. — 8th. Oxford, Liverpool, Cock- 
 ermouth, North Shields. — 10th. Eastbourne. 
 —20th. Munster, Peckeloh.— 23rd, 26th. 
 Culloden. — 28th. Liverpool, Carlisle, Cul- 
 loden. — 29th. Liverpool, Carlisle, Culloden, 
 Allenheads — 30th. Weybridge, Hawsker; 
 Brussels; Munster; Lennep; Peokeloh. — 
 31st. Lennep ; Peckeloh. 
 1870. Feb. 1. Paris, Calais ; London, Diss, Eastbourne, 
 Wisbech, Boston, Eoyston, Little Wratting, 
 Norwich, Somerleyton, North Shields, 
 Culloden; Brussels, Kain near Tournay, 
 Euhrort, Munster ; Munich ; Lennep ; 
 Peckeloh ; Dresden, Grceditz ; Grullenberg ; 
 Liohtenberg ; KcesHn, Kcenigsberg ; Cracow. 
 —2nd. Culloden, Weybridge.— 3rd, 4th. 
 Culloden. — 11th. York, Hawsker, North 
 Shields, Taunton, Wilton, Streatly, Little 
 Wratting, Cardington. — 12th. Helston, 
 Coekermouth. — 17th. Leipzig. — 19th. 
 Truro. — 21st. Hawarden. — 23rd. Culloden. 
 — 27th. PecLe'oh. — 28th. Weybridge, 
 Hawarden, Culloden. 
 
 — Mar. 1. Hawarden. — Brd. Cardington, Boston. — 13th. 
 
 Oxford, Taunton, Boston, Hawsker. — 14th. 
 Guernsey. — 22nd. Stonyhurst, York, Little 
 Wratting. — 24th. York. — 25th. Weybridge. 
 —28th. Lichtenberg. — 30th. Oxford, 
 Valentia ; Westphalia. 
 
 — April 5. Athens ; Fiume ; Piacenza, Volpeglino, North 
 
 de Italy ; Macon, Anglers, le Mans, Nantes, 
 Brest, Paris, all the north, of France; 
 London; Brussels, Louvain, Kain, Gram- 
 mont ; Flushing, Utrecht, Leeuwarden ; 
 Splugen, Groechen, Vuadens, all north-east- 
 ern Switzerland; Mayence, Sinzig, Bonn, 
 Westphalia ; aU North Germany ; Buda, 
 Isohl, Feldkirk ; Munich, Deutsch Krone ; all 
 Saxony ; Karnik near Posen. — 18th. Green- 
 wich ; Peckeloh, Lennep ; Stettin. — 23rd. 
 Papenburg.- — 25th. Eeitzenhain. 
 
 — May 19. Greenwich. — 20th. Paris ; London ; Mannheim ; 
 
 Munster ; Zurich ; Hermannstadt, Oravitza, 
 Fiume, Tisza Fured, Debreczin, Edel^ny, 
 Bechnitz, Gospic. 
 
APPENDIX. 249 
 
 1870. June 1. Louvain. 
 
 — Aug. 1. Peokeloh.— 3rd. Amsterdam.— 19th. Munster; 
 
 Carthaus near Dulmen. — 20th. Groninguen ; 
 Munster, Peckeloh; Leipzig.— 21st. Vol- 
 peglino. 
 
 — Sept. 2. Athens. — 3rd. Greenwich; Hamburg; Doebehi; 
 
 Niederorsohel. — Ith. Workum, Zuidbroek; 
 Niederorschel ; Norburgoff Alsen; Schleswig. 
 ^18th. Hamburg. — 21st. Hamburg, Nor- 
 "" burg, Schleswig ; Lichtenberg. — 22nd, 23rd. 
 Peckeloh.— 24th. Moncalieri and all Pied- 
 mont ; Vendome ; London, Hawkhurst ; 
 Brussels, Louvain, Stavelot; Groninguen; 
 Mayenoe ; Zurich ; Vienna, Kremsmunster ; 
 Prague, Eger; Buda,Edeleny, Obernberg sur 
 Inn, Enzersdorf im Thale ; Niederorschel, 
 Carthaus near Dulmen, Weisenheim am Bry ; 
 Munster ; Peckeloh, WoUgast ; Alsen, Nor- 
 burg off Alsen, Schleswig ; Berlin, Danzig. — 
 25th. Greenwich ; Ostend, Kain ; Ouddorf, 
 Welna,Boekhorst, Terborgh and all Zealand ; 
 Zurich ; Munster ; Hamburg ; Weisenheim 
 am Bry, Carthaus near Dulmen ; Peckeloh, 
 Schleswig ; Eehfeld ; Danzig. — 26th. Green- 
 wich ; Guddorp, Welna, Boekhorst, Terborgh 
 and all Zealand, Hamburg, Keitum ; Weisen- 
 hein am Bry ; Peckeloh ; Lichtenberg. — 
 27th. Hamburg ; Schleswig ; Peckeloh. — 
 20th. Lichtenberg. 
 
 — Got. 1. England ; Westphalia. — 2nd, 3rd. England. — 
 
 14th. Vend6me ; Greenwich, England ; 
 Holland ; Schcenenberg (canton of Zurich) ; 
 Edeleny ; Groeditz Bautzen ; Munster ; 
 Putbus, Hamburg ; Lichtenberg ; Cracow. — 
 15th. Holland.— 17th, 18th. England.— 
 20th. Vendome ; England ; Aarau, Brugg, 
 Muri ; WestphaUa ; Kiesa. — 21st. England ; 
 Norburg off Alsen. — 22nd. England ; 
 Cologne ; Hinterhermsdorf ; Cracow. — 23rd. 
 Fiume. — 24th. Bagdad ; Athens ; Constan- 
 tinople, Lala Tchiflik, to the south of Andri- 
 nople ; Roustchouck, Orsova ; Lisbon, Oporto, 
 Madrid ; Palermo, Catania, Otranto, Eome, 
 Florence, Fiesole, Perugia, Leghorn, Milan ; 
 Trieste, Lissa, Lesina, Fiume ; Saint-Petei 
 near Goerz, Modena, Varallo, Moncalieri. 
 
250 THE POLAE AURORA. 
 
 Alexandria ; Paris, Tours, Metz, the whole 
 of France ; London, Greenwich, Torquay, 
 Scarborough, Penzance, Valentia, the whole 
 of England; Brussels, Louvain, Kain, 
 Ostend, &c. ; aU Holland ; Bellinzona, 
 Lugano, Monte Generoso, Brusio, Splugen, 
 Coire, Einsiedeln, Berne, Altorf, Geneva, 
 all northern Switzerland ; Vienna, Krems- 
 munster ; Hermannstadt, Ssechsisch-Eegen ; 
 Karlsburg ; Leipzig, Saxony ; Mnnster, 
 Hamburg-; Niederorschel, Carthaus, Pecke- 
 loh ; Berlin, Stettin, Breslau, Danzig and 
 North Germany. — 25th. Corfu ; Athens, 
 Greece ; Constantinople, Turkey in Europe, 
 Orsova, Eustchuck, Sarajevo, Prevesa; 
 Lisbon, Oporto, Madrid; Cataro, Castelnu- 
 ova, Lesina, Lissa, Eiume, Trieste, Palermo, 
 Catania, Otranto, Naples, Eome, Fiesole, 
 Florence, Modena, MUan, Genoa, Turin, 
 Moncalieri; Paris, Tours, Metz and all 
 France ; London, Scarborough ; Brussels, 
 Louvain, Kain, Ostend ; Vienna, Krems- 
 munster, OberhoUabrmm, Presburg, Buda, 
 GyaUa ; Munster, Niederorschel, Keitum, 
 Hamburg ; Leipzig, Saxony ; Schleswig, 
 Peckeloh, Berlin, Breslau and all Germany. 
 — 26th. Athens.— 27th. Athens ; Monte 
 Generoso ; England ; Hamburg. • — 28th. 
 Athens ; England ; Hamburg.^29th. Ham- 
 burg ; Lichtenberg. — 30th. England. 
 
 1870. Nov. 1. England ; Hamburg. — 8th. Leeuwarden ; 
 
 Schleswig; Leipzig, Saxony. — 14th, 17th, 
 • 18th. England ; Saxony. — 19th. England ; 
 Brussels, Louvain, Verviers ; Zurich, Coire ; 
 Munster ; Schleswig ; Eger ; Leipzig, many 
 parts of Saxony ; Niederorschel ; Peckeloh. 
 —21st. England.— 22nd. Mediasch (Tran- 
 sylvania) ; England. — 25th. England. — 27th, 
 Brunn. 
 — Dec. 15. England. — 16th. England, Westphalia; Kei- 
 tum; Schleswig; Peckeloh.— 17th. Ven. 
 d6me ; England ; Brussels. Louvain, 
 GroBohen; Munster; Keitum; Schleswig; 
 Zittau; Peckeloh, Putbus ; Breslau. — 22nd. 
 Schleswig. — 26th. Peckeloh. 
 
 1871. Jan. 12. Louvain. — 13th. London ; Louvain ; Cologne, 
 
APPENDIX. 251 
 
 Munster ; Peckeloh, Schleswig ; Tharandt ; 
 Breslau. — 14th. Louvain. — 15th. Schleswig ; 
 Breslau. — 16th. Louvain. 
 1871. Feb. 5. Breslau.— 9th. Cleves; Putbus.— 11th. Eng- 
 land ; Cleves, Emden, Westphalia, Keitum ; 
 Peckeloh ; WoUgast ; Putbus. — 12th. Eome, 
 Frascati, Florence, Modena, Volpeglino, 
 Moncalieri ; Greenwich, West Coasts of 
 England, Louvain ; Mayenoe, Cleves ; Altorf, 
 Coire, Bagatz ; Vienna, Eger ; Daschitz 
 (Moravia) ; Saxony ; Munster ; Niederor- 
 schel ; Peckeloh ; Weserleuchtthurm ; WoU- 
 gast ; Breslau, Putbus, Kceshn, Stettin. — 
 13th. England.— 14th. Volpeglino.— 15th. 
 Eome ; Zurich. 
 
 — Mar. 12. London. — 13th. GruUenberg (Saxony). — 14th. 
 
 Bautzen, Dresden, Wermsdorf ; Grceditz, 
 Zittau, Plauen, Koenigstein. — 16th. Eoohe's 
 Point ; Munster ; Peckeloh.— 17th. Pied- 
 mont. — 18th. Zurich; Goerisch; Goerlitz, 
 Oberwiesenthal. — 21st. Munster. — 22nd. 
 Leeuvsrardeu. — 23rd. Venice, Leeuwarden, 
 Emden ; Cleves ; Munster ; WoUgast ; 
 Peckeloh.— 29th. Emden. 
 
 — April 1. London ; Brussels ; Cleves ; Treves ; Breslau. 
 
 — 2nd. Stettin. — 8th. Turin, Moncalieri ; 
 Breslau. — 9th. Palermo, Perugia, Piacenza, 
 Padua, Milan, Trente, Tortona, Volpeglino, 
 Alexandria, MonoaUeri, Turin, Genoa ; 
 Anglers ; England ; Brussels, Louvain ; 
 Zurich, Glarus, Sargans ; Vienna, Prague ; 
 Mayence, Frankfort ; Keitum, Weserleucht- 
 thurm ; Bautzen ; Stettin, and many parts 
 of Germany. — 10th. Moncalieri, Alexandria, 
 Padua, &c., London; Peckeloh. — 11th. 
 Aosta ; Westphalia ; Peckeloh. — 13th. 
 Palermo, England. — 14th. Leipzig, Dresden, 
 Wermsdorf, Groeditz, Zittau, Koenigstein,' 
 Plauen, and other parts of Saxony, Peckeloh, 
 Stettin. — 15th. Palermo, Piacenza; Pecke- 
 loh ; Stettin. — 16th. London ; Stettin. — 
 17th. Volpeglino ; Stettin. — 18th. Palermo, 
 Perugia, Urbino, Florence, Lodi, Alexandria, 
 MoncaUeri, Volpeglino, Bra, Piedmont, 
 Lombardy ; Zurich, Aarau, Coire, Saint-Gall, 
 Winterthur ; CiUi ; Oberwiesenthal, Groeditz, 
 
252 THE POLAE AUEORA. 
 
 Leipzig ; Breslau ; Putbus, Koeslin, Stettin, 
 WoUgast, Plensburg.— 19th. Lohn.— 21st. 
 Ulm.— 22nd. Paris.— 23rd. Palermo, Lodi, 
 Turin, Moncalieri, Alexandria, Bra, Genoa, 
 Volpeglino ; Munster. 
 
 1871. May 8. London, England.— 16tli. England.— 17th. 
 
 England; Peckeloh.— 18th. Berne.— 19th, 
 20th, 22nd, 26th. England. 
 
 — June 7, 12. Athens ; MonoaUeri. — 13th. Cleves. — 14th. 
 
 Cleves ; Peckeloh.— 16th. Turin.— 18th. 
 Athens; Moncalieri. — 27th, Moncalieri; 
 Oxford. 
 
 — July 14. Moncaheri. — 25th. Eoche's Point. 
 
 — Aug. 10. Peckeloh.— 11th. Valentia.— 16th. England. 
 
 — 21st. London, Ireland. — 28rd. Zurich ; 
 Emden. — 24th. Aberdeen, Eoche's Point ; 
 Brussels. 
 
 — Sept. 4. Ireland. — 7th. Houlgate (Calvados) ; WoUgast. 
 
 —16th. Eoche's Point.— 19th. Emden. 
 
 — Oct. 6. Emden. — 10th. Zurich, Aarau; Mayence. — 
 
 11th. WoUgast.— 13th. London; Peckeloh. 
 — 15th. Peckeloh. — 16th. London. 
 
 — Nov. 2. Volpeglino, Moncalieri, Aosta; Groninguen, 
 
 Emden ; Bonn ; Gyalla (Hungary) ; Eger ; 
 Opladen, Husum, Kiel ; Bergen on Eugen, 
 Woolgast, Danzig. — 3rd. Paris ; GyaUa. — • 
 4th. Peckeloh. — 5th. GyaUa.— 7th. Pec- 
 keloh. — 9th. Modena, Genoa, Turin, Mon- 
 calieri, Volpeglino ; Anglers, Paris, Brest ; 
 Greenwich, England ; Entremonts near 
 Binche (Belgium); Emden; Bonn; Genoa; 
 Woolgast, Opladen, Peckeloh ; Kiel; Dingel- 
 stedt ; Leipzig. — 10th. Genoa, Lodi, Mon- 
 dovi, Turin, Moncalieri, Volpeglino, Aosta ; 
 Paris ; Greenwich, SeUly ; Entremonts ; 
 Bonn ; Eger ; Woolgast, Opladen, Eoessel, 
 Dingelstedt ; Danzig. — 14th. Genoa ; Alex- 
 andria. — 15th. Genoa. — 17th. Danzig. — 
 18th. Emden.— 20th. Aosta, Danzig.— 24th. 
 Volpeglino. 
 
 — Deo. 6. Peckeloh. — 10th. Emden.— 14th. Peckeloh.— 
 
 18th. London. — 31st. Eoche's Point. 
 
 1872. Jan. 3. London. — 5th. Modena. — 6th. Palermo. — 7th. 
 
 Florence, Modena, Genoa, Aosta. — 9th. 
 Florence. — 15th. Aosta. — 18th. Emden. — 
 21st. Florence. — 27th. Peckeloh. — 30th. 
 
APPENDIX. 253 
 
 Volpeglino ; London. — 31st. Greenwich ; 
 Lichtenberg. 
 1872. Feb. 1. Florence. — 2nd. Modena; Weybridge.— 3rd. 
 Algiers; Brighton, Sidmouth. — 4th. Bom- 
 bay ; Lahore ; Suez, Syena, Cairo, Alex- 
 andria ; Athens ; Constantinople ; Malta ; 
 Palermo, Otranto, Bome, Florence, Genoa, 
 Moncalieri, Aosta, &o., in general all Italy ; 
 Mostar, Lesina, Pola, Trieste ; Lisbon ; 
 Madrid, Barcelona ; Marseilles ; MontpelUer, 
 Toulouse, Bordeaux, Lyons, Macon, Poitiers, 
 Tours, Brest, Paris, Nancy, &c., Greenwich, 
 SciUy, Stonyhurst, Dublin, whole of England ; 
 Louvain, Cleves, Cologne, Aix-la-ChapeUe, 
 Bonn ; Geneva, Zurich and aU Switzerland ; 
 Kremsmimster, Czernowitz, Salzbourg, Her- 
 mannstadt, Lemberg, Cracow, Prague ; 
 Saxony ; Munster ; Peckeloh ; Bossel, 
 WoUgast ; Breslau ; Danzig; Nakskow ; 
 Bandholm on Laaland, - &c. : all Europe 
 from Turkey and Sicily to Scotland. — 
 5th. Eome, Moncalieri; Brighton ; Zurich ; 
 Freiberg. — 6th. Moncaheri ; Brighton ; 
 Hinterhermsdorf. — 8th. Genoa, Aosta ; 
 Zurich ; Lichtenberg. — 9th. Genoa. — 10th. 
 Volpeglino. — 11th. Brighton. — 17th. Mon- 
 caheri ; Constance. — 22nd. Emden. — 23rd. 
 Culloden. — 26th. Mondovi, Moncalieri ; 
 Emden.— 27th. Genoa, Alexandria, Volpe- 
 glino. 
 
 — Mar. 1. Florence. — 2nd. Paris. — 4th. Moncalieri ; 
 
 Emden. — 5th. Moncalieri, Aosta ; Emden. 
 ■ — 6th. Messina, Palermo, Modena; London; 
 Emden ; Peckeloh. — 7th. Genoa, Mon- 
 caheri ; London. — 8th. Moncalieri, Modena ; 
 London ; Lichtenberg. — 9th. Moncaheri. — 
 10th. Modena ; Emden ; Lichtenberg. — 
 11th. Modena; Lichtenberg, Stettin. — 12th. 
 Moncaheri, Genoa ; Emden ; Lichtenberg. 
 — 14th. Emden. — 16th. Alexandria. — 19th. 
 Halifax. — 20th. Moncalieri ; Norwich ; 
 Emden. — 27th, 29th. Genoa, Mondovi. — 
 30th. Mondovi ; London ; Lichtenberg. — 
 31st. Cantalupo: Emden. 
 
 — April 1. Alexandria, Volpeglino; Emden. — 2nd. Alex- 
 
 andria. — 3rd. Moncalieri ; Stonyhurst ; 
 
254 THE POLAE AUROBA. 
 
 Emden. — 6th. Genoa, Moncalieri. — 7th. 
 Mondovi. — 8th. Lyons. — 10th. Milan, 
 Mondovi, Moncalieri, VolpegUno ; Paris, 
 Brest; Stonyhurst. — 11th. Genoa, Volpe- 
 glino ; Greenwich ; Emden, Peckeloh. — 
 12th. Piacenza. — 13th. Piacenza; Emden. 
 — 14th. Mondovi, Aosta ; Emden. — 15th. 
 Moncalieri, Mondovi, Aosta ; department of 
 the Yonne, Sevres ', Greenwich, Stonyhurst. 
 —17th, 22nd, 24th, 29th, 30th. Emden. 
 There were in this month nine days of 
 aurora in England, dates and places of 
 observation not indicated. 
 1872. May 2. Westphalia. — 7th. Peckeloh, Westphalia.— 
 9th. Florence, Venice, Milan, Mondovi, 
 Moncalieri, Aosta ; Asgiers ; Verdingen 
 (near Cologne). — 10th. Turin.— 15th. Aosta. 
 — 17th. Volpeglino. There were in this month 
 sIk days of auroras in England, dates and 
 places not given. 
 
 — June 4, 5. Paris. — 6th. Sevres. — 7th. Emden.— 10th. 
 
 Anglers. — 12th. Emden. — ^21st. Vienna, 
 Cracow. — 23rd. Nancy. — 30th. Emden. — 
 There were in this month three days of 
 auroras in England, dates and places not 
 given. 
 
 — July 1, 2. Brighton. — 5th. Sfevres. — 6th. Genoa, 
 
 VeUetri ; Sevres. — 7th. P^aris, Brest ; Ports- 
 mouth, BridportjLeenane (Ireland) ; Anvers; 
 Mayence ; Zurich ; Cracow ; Dingelstadt, 
 Kiel. — 8th. Madrid ; Greenwich, Oxford. — • 
 19th. Anglers; Greenwich.— 26th, 28th. 
 Lichtenberg. — 30th. Brighton. — 31st. An- 
 glers. 
 
 — Aug. 1. Brighton ; Lichtenberg. — 2nd. North Shields. 
 
 • — 3rd. Aosta ; Guernsey ; SOloth ; Zurich ; 
 Cracow ; Stettin. — 4th. s CuUoden ; Emden ; 
 Laibaoh, Cracow. — 5th. Anglers. — 6th. 
 Brighton; Zurich; Tiszafured (Hungary). 
 — 8th. Modena, MoncaUeri, Volpeglino; 
 Anglers ; Guernsey ; Helston, Taunton, Ox- 
 ford, Hawarden, Llandudno, CuUoden, 
 SUloth ; Lichtenberg. — 9th. Geneva, Turin, 
 Moncalieri ; Volpeglino ; Beltort ; York ; 
 Llandudo ; Emden ; Lichtenberg. — 10th. 
 Allenheads; Prague. — 13th. CuUoden. — 
 
APPENDIX. 255 
 
 14th. Brighton, Oxford, Llandudno, Cullo- 
 den, Stonyhurst ; Cleves, Mayenoe, Darm- 
 stadt ; Bremen, Peokeloh ; Oraoow ; Leipzig ; 
 Stettin, KcBslin.— 15th. Eome (?).— 25th. 
 Lisbon (?) ; Westphalia ; Wermsdorf 
 (Saxony). — 26th. 86vres. — 27th. Sevres ; 
 Liohtenberg. — 28th. Florence, Genoa, 
 Monoalieri, Volpeglino, Aosta ; York. — 29th. 
 Brighton. 
 1S72. Sept. 2. Paris, Sevres ; Brighton, Cockermouth ; West- 
 phalia; Berlin. — 3rd. Eome; Paris; Sfevres; 
 Hawarden ; Llandudno ; Koeslin. — 4th. 
 Paris, Sevres ; London, Brighton. — 5th. 
 Paris, Sevres ; Brighton, York.— 6th. York. 
 —8th. Eccles. — 9th. Hawarden, Stony- 
 hurst, York, Oockermouth, Silloth. — 11th. 
 Sevres. — 14th. Emden. — 17th. Oxford, 
 Silloth.— 21st. Silloth.— 27th. Sevres.— 
 28th. Paris, Sevres.— 29th. Volpeglino; 
 York, Carlisle, North Shields. 
 
 — Oct. 1. Paris. — 2nd. London, Valencia*^ — 3rd. Silloth, 
 
 North Shields. — 5th. Emden. — 6th. Sevres; 
 London ; Brighton ; Emden ; Peckeloh. — ■ 
 7th. Modena ; Aosta ; Paris ; Brighton ; 
 Peckeloh.— 8th. Paris, Sfevres.- 9th. Mo- 
 dena.— 10th. Paris.— 11th, 12th. Emden. 
 —13th. Peckeloh.— 14th. Sfevres; Brest; 
 Guernsey ; Peckeloh. — 15th. MoncaHeri, 
 Aosta ; Sfevres ; Peckeloh. — 16th. Sfevres. 
 — 17th. Sevres ; Oxford, Carlisle ; Peckeloh. 
 —18th, 19th. Peckeloh.— 22nd. Sevres; 
 Emden. — 23rd. Emden ; Lichtenberg. — 
 24th, 25th. Lichtenberg.— 26th. Paris; 
 Emden ; Peckeloh ; Lichtenberg. — 27th. 
 Paris, Emden. — 28th. Oxford. — 30th. 
 Paris. — 31st. Brighton. 
 
 — Nov. 1. Paris ; Lichtenberg. — 2nd. Brighton ; Liohten- 
 
 berg. — 4th. Lichtenberg. — 5th. Emden. — 
 6th. London, Shields, Wick.— 9th. Wick.— 
 11th. Carlisle, Cockermouth, Stonyhurst. 
 —15th. Helston. — 19th. Paris ; Em- 
 den ; Peckeloh. — 20th. Paris ; Cambridge ; 
 Peckeloh.— 21st. Wick.— 24th. Liohten- 
 berg. — 25th. Moncalieri ; VolpegHno ; Paris ; 
 Lichtenberg. • — 27th. Palermo, Messina, 
 Perugia, Monoalieri ; Gbttingen ; Liohten- 
 
256 THE POLAR AURORA. 
 
 berg.— 28tli. Paris; Emden.— 29th. Dan- 
 zig. 
 
 1872. Dee. 1. Oxford; Peckeloh.— 2nd. Cooliermouth.— 3rd. 
 
 Milan, Piaoenza, Turin, Moncalieri, Ivrea, 
 Aosta; Liohtenberg. — 4th. Trebizond.— 5th. 
 Trebizond ; Lemberg. — 6th. Lemberg ; 
 Peckeloh. — 9th. Greenwich, Oxford, Stony- 
 hurst.— 11th. Perugia.— 14th. Moneaheri, 
 Volpeglino, Aosta. — 22nd. Munster.— 23rd. 
 Volpeglino, Aosta ; Peckeloh. — 24th. Gottin- 
 gen, Peckeloh; Dallund. — 25th. Gottingen. 
 — 26th. Stonyhurst; Peckeloh; Lichtenberg. 
 —27th. Peckeloh, Dallund.— 28th. Chiari, 
 Turin, Moncalieri. — 29th. Munster. 
 
 1873. Jan. 1. Greenwich. — 3rd. Brighton, Liverpool. — 5th. 
 
 ISforth Shields. — 6th. Aosta. — 7th. Paris; 
 Adriatic, lat 44° 40' N. long. 11° 35' E. ; 
 Brighton, Eastbourne, Portsmouth, Green- 
 wich, Lymington, "Weybridge, Oxford, 
 Eoyston, Stonyhurst. — 10th. Carhsle. — 
 16th. Streatley.— 19th. Weybridge.— 20th. 
 Volpeglino. — 23rd. Aosta. — 25th. WoUgast. 
 —27th, 30th. Perugia. 
 
 — Feb. 19. Aosta.— 20th, Stonyhurst.— 22nd. Volpeglino, 
 
 Aosta ; Carlisle, Cockermouth, — 23rd. Volpe- 
 glino ; Weybridge. — 27th. Perugia, Mon- 
 calieri; Carlisle, Bywell. — 28th. Moncalieri 
 
 — Mar. 10. Greenwich. — 20th. Brighton. — 21st. Volpe- 
 
 glino. — 22nd. Volpeglino, Ao ta ; Oxford 
 Wisbech. — 23rd. Perugia, Leghorn, Volpe- 
 glino, Aosta. — 24th. Aosta. 
 
 — April 1. Portsmouth, Brighton, Oxford, Wisbech, 
 
 Stonyhurst. — 2nd. Guernsey ; Oxford. — 
 18th. Ecoles, Halifax, HuU, York, Stony- 
 hurst, Carhsle, Cockermouth, SiUoth. — 19th. 
 Oxford, Hahfax, Hull, Stonyhurst. — 20th. 
 Oxford, Stonyhurst. — 21st. Norwich. — 22nd. 
 Stonyhurst.— 24th, 28th. Brighton.— 30th. 
 Guernsey ; Brighton. 
 
 — May 14. Genoa, Aosta. — 15th. Genoa, Aosta; Brighton. 
 
 • — 23rd. Moncalieri, Aosta. — 24th. Aosta. 
 
 — June 25. Stonyhurst. — 26th. Perugia, Alexandria, Mon- 
 
 calieri, Bra, Volpeglino, Aosta. — 27th. 
 Perugia, Moncalieri, Bra, Volpeglino, Aosta. 
 
 — July 16. Brighton. 
 
 — Aug. 6. Oxford.— 13th. Perugia, Umbria.— 15th. Birr 
 
APPENDIX. 257 
 
 Castle (Ireland). — 18th. Stonyhurst. — 21st, 
 22iid, 23rd, 31st. Birr Castle. 
 
 1873. Sept. 15. Birr Castle.— 20th. Carlisle, Birr Castle.— 
 
 21st, 29th. Birr Castle. 
 
 — Oct. 11. Birr Castle.— 12th. Silloth, Birr Castle.— 13th. 
 
 Hidl.- 15th. Halifax. — 18th, 30th. Birr 
 Castle. 
 
 — Nov. 2. Birr Castle.— 12th, 13th. Hull. 
 
 — Deo. 9. Birr Castle. — 17th. Piacenza, Turin, Mon- 
 
 caheri, Volpeglino. — 19th. CarUsle. — 26th. 
 Birr Castle. 
 
 1874. Jan. 6. Cockermouth. — 12th. Birr Castle. — 16th. 
 
 Weybridge Heath, Silloth, Birr Castle. — 
 17th. Stonyhurst, Carlisle. — I8th. CarUsle. 
 —24th. Helston. 
 
 — Feb. 4. Perugia, Florence, Leghorn, Udina, Ivrea. 
 
 Mondovi; Toulouse; Portsmouth, Green- 
 wich, Taunton, Weybridge Heath, Salisbury, 
 Streatley, Leicester, Oxford, Wisbech, Eccles, 
 I5ywell, Whitehaven, Cambridge, Sunder- 
 land, Stonyhurst, Cockermouth, Allenhead, 
 Silloth, Birr Castle ; Vienna, Prague ; WoU- 
 gast. — 5th. Silloth, Birr Castle. — 8th. 
 Modena.— 16th. Weybridge Heath.— 17th. 
 SiUoth.— 18th, 19th. Modena. 
 
 — Mar. 7. Pare Saint-Maur near Paris (?) ; ByweU, 
 
 North Shields, SiUoth, Birr Castle.— 9th, 
 18th. Birr Castle. 
 
 — AprU 7, 9, 14. Birr Castle. 
 
 — May 3. Birr Castle. 
 
 — June 3. Oxford, Liverpool. — 13th. Guernsey. 
 
 — July 2. HaUfax. — 22nd. Streatley. 
 
 — Aug. 31. SUloth. 
 
 — Oct. 3. England. — 4th. Greenwich, England. — 13th, 
 
 14th, 18th. England. — 22nd. MoncaUeri, 
 Pignerol, Volpeglino. — 29th. Pare Saint- 
 Maur. 
 
 — Dec. 7. Ivrea, Volpeglino. 
 
 1875. Feb. 23. Nedanocz (Hungary). 
 
 — Mar. 4. Cardington. 
 
 — AprU 26. Brighton.— 30th. Streatley. 
 
 — June 2. Volpeglino. 
 
 — July 14. Stonyhurst.— 24th. SUloth.— 29th. Cardmgton. 
 
 — Sept. 20. SaUsbury. 
 
 — Oct. 2. Weybridge Heath, SUloth. 
 
 — Nov. 5, 6. Cardington. — 11th; Volpeglino. 
 
 18 
 
258 THE POLAE AUEOEA. 
 
 1875. Dec. 8. North Shields.— lath. Volpeglino.— 21st. Wey- 
 
 bridge Heath. 
 
 1876. Feb. 19. Liverpool, Whitehaven, Caloethorpe, Stony- 
 
 hurst, North Shields. 
 
 — Mar. 13. Perugia, Arena. — 21st. Perugia. 
 
 — April Pour days of auroras in England, dates not 
 
 given. 
 
 — June Two days of auroras in England, dates not 
 
 given. 
 
 — Dee. 5. Weybridge. 
 
 1877. Jan. 23. Guernsey. 
 
 — Nov. 10, 28. Torquay. 
 
 1878. Mar. 25. Carlisle. 
 — ■ April 3. Torquay. 
 
 — June 1. Brussels. — 8rd. Breslau. 
 
 1879. No aurora in Europe this year below lat. 55°. 
 
 1880. Mar. 17. Grypskerk. 
 
 — April 8, 14. North Shields. 
 
 — Aug. 10. Shap (Westmoreland). — 11th. Stonyhurst. — 
 
 12th. Brighton, Strathfield, Oxford, Leicester, 
 Bolton, Whitby, Stonyhurst, Carlisle, Silloth, 
 North Shields.— 13th. Torquay. 
 
 — Nov. 3. Greenwich, Lowestoft, Cambridge, Liverpool, 
 
 Cirencester, Bootham, Downport, Dublin ; 
 Wilhemsbafei.- 27th. Bradford. 
 
 1881. Jan. 31. Parma, Alexand_-ia, Moncalieri, Volpeglino; 
 
 all England; Brussels, Maldeghem, Mes- 
 sines, Louvain, Croix ; Utrecht J WUhelms- 
 hafen, Buxtehude (near Hamburg), aU the 
 north-east of Germany ; Hohenpeissen- 
 berg, Lomtrach, Memmingen, Meersburg, 
 Isny. 
 
 — Feb. 1. Atlantic, lat. 48° N.-16° W.— 27th. Atlantic, 
 
 lat. 49° N.-25° W.— Several auroras in 
 England from the 7th to the 10th, exact 
 dates and places unknown. 
 
 — Mar. 19, 20. SiUoth. 
 
 — April 20. Cambridge, Llandudno, Stonyhurst ; Atlantic, 
 
 lat. 41° N.-67° W. 
 
 — Sept. 12. Atlantic, lat. 50° N.-32° W. and lat. 43° N.- 
 
 52° W. — 13th. Alexandria ; England ; Atlan- 
 tic, lat. 42° N.-37° W.— 14th. Atlantic, lat. 
 45° N.-46° W. 
 
 — Oct. 16. Atlantic, lat. 42° N.-65° W., 44° N.-56° W., and 
 
 47° N.-52° W.— 21st, 22nd. Carlisle. 
 
 — Nov. 23. Cardington. 
 
APPENDIX. 259 
 
 1881. Deo. 23. Atlantic, lat. 50° N. in the whole space between 
 
 20° and 40° W. long. 
 
 1882. Jan. 19. Atlantic, lat. 41° N.-72° W. and 48° N.-34° W. 
 
 — Feb. 6. Atlantic, lat. 43° N.-51° W.— 15th. Atlantic, 
 
 lat. 35° N.-15° W.— 16th, 17th. Bermerside. 
 — 20th. Bedford, Bermerside. 
 
 — Mar. 19. Atlantic, lat 41° N.-59° W.— 21st. Stonyhurst, 
 
 — -April 13, 14, 15. Middle of the Atlantic between 41° and 
 
 48° N. and 25° and 70° W.— 16th. Hanover; 
 middle of the Atlantic— 18th, 19th, 20th, 
 21st. Middle of the Atlantic. 
 
 — May 11. Atlantic, lat. 41° N.-62° W. — 14th. M^ru 
 
 Ternat (Haute-Marne), Pornic ; Worcester, 
 Oldham, Dublin; Atlantic, lat. 41° N.-27°W. 
 and 47° N.-17° W. — 29th. Atlantic, lat. 
 41° N.-66° W. 
 
 — July 16. Atlantic, from 40° to 42° N. and from 64° to 
 
 67° W. 
 
 — Aug. 4. Atlantic, from 37° to 47° N. and from 38° to 
 
 75° W.— 5th. Stonyhurst.— 9th. Atlantic, 
 lat. 42° N.-65° W.— 11th. Atlantic, lat. 40° 
 N.-65°W. and lat. 43° N.-49° W. — 14th. 
 Atlantic, lat. 41° N.-61° W.— 22nd. Atlantic, 
 lat. 41° N.-57° W.— 23rd. Stonyhurst.— 30th. 
 Worcester. 
 
 — Sept. 4. Atlantic, lat. 43° N.-60° W.— 5th. Atlantic, lat. 
 
 45° N.-48° W.— nth. Atlantic, lat. 41° N.- 
 62° W.— 12th. Atlantic, lat. 42° N.-54° W. 
 and lat. 49° N.-12° W.— 20th. Atlantic, lat. 
 58° N.-18° W. 
 
 — Oct. 1 Halifax. — 2nd. Mondragona, Florence, Mon- 
 
 calieri ; Paris, pare Saint-Maur, Saint-Leu, 
 Taverny, Evreux, La Teste, Nantes, Dinard, 
 Cherbourg, LandeUes, Seez, Laon, Amiens, 
 LiUe ; Guernsey ; Torquay, Greenwich, Ox- 
 ford, Leicester, Hull, Scarborough, Chelten- 
 ham, Newcastle-on-Tyne, Dublin, &c. ; 
 Brussels, Louvain, Utrecht ; Basle, Trogen ; 
 Braganza ; Pola, Budapest, Breslau, Griin- 
 berg, Swinemunde ; all the Atlantic. — 
 3rd. Oxford, Hull.— 4th. All the Atlantic— 
 5th. Stonyhurst, Silloth; Atlantic. — 8th, 
 15th, 16th, 17th. Atlantic— 18th. Croydon. 
 —22nd, 24th, 28th, 29th. Atlantic— 30th. 
 Stonyhurst. 
 
 — Nov. 1. Oxford.— 11th. Atlantic— 12th. Stonyhurst, 
 
2G0 THE POLAR AXJKOEA. 
 
 York, Sillotli; Atlantic. — 13fch. Stonyhnrst, 
 Bolton, York ; Atlantic. — 14th. Stonyhnrst, 
 York; Atlantic— 15th, 16th. York.— 17th. 
 Eome, Florence, Moncalieri, Volpeglino ; 
 Nice, Marseilles, Grenoble, Valencia, Mont- 
 pellier, Paris, Laon, Cherbourg, Saint-Brieuc, 
 Ploermel, Douai, &c. ; Guernsey ; Torquay, 
 Greenwich, Osborne, Oxford, Hull, Halifax, 
 Stonyhurst, York, Silloth, &c. ; Brussels, 
 Bruges, Tournai, Antwerp, all Belgium; 
 Utrecht, Zieriksee, all Holland ; all Switzer- 
 land; Kume, Pola, Lussinpiccolo, Agram, 
 Boveredo, ■ Boehm, Aicha ; Atlantic. — 18th. 
 Torquay, Cardington ; Atlantic. — 19th, 20th. 
 Oxford; Atlantic. — 25th. Atlantic. 
 
 1882. Dec. 12. Atlantic— 15th. Atlantic, between 30° and 
 
 59° W.— 19th. Oxford, York.— 23rd. Hahfax. 
 
 1883. Jan. 24. Geestemunde. 
 
 — Feb. 1. All the Atlantic— 2nd. West of the Atlantic. 
 
 —12th. HuU.— 15th. Brixham (?).— 24tb. 
 Cambridge. 
 
 — Mar. 3. Oxford.— 4th, 8th. Atlantic— 10th. Oxford.— 
 
 28th. Atlantic. 
 
 — April 2. Whitchurch. — ^Srd, 24th. Stonyhurst ; Atlantic. 
 
 — May 11, 14. Stonyhurst.— 26th. Whitchurch. 
 
 — June 30. Atlantic. 
 
 — July 1, 6, 29, 30. Atlantic. 
 
 — Aug. 6. Whitchurch. — 7th, 22nd. Atlantic. — 30th. 
 
 Stonyhinrst. 
 
 — Sept. 4. Atlantic— 5th. Silloth; Atlantic. — 7th. At- 
 
 lantic— 8th. Stonyhurst.— 11th, 12th, 15th, 
 16th, 23rd, 24th, 25th. Atlantic 
 
 — Oct. 4. Stonyhurst; Atlantic. — 5th. Cambridge, Stony- 
 
 hurst, Carlisle, SiUoth ; Atlantic. — 16th, 
 31st. Atlantic. 
 
 — Nov. 1. Atlantic from 30° to 75° W.— 2nd. Atlantic, 
 
 from 13° to 55° W.— 5th. Atlantic, lat. 
 46° N.-49° W.— 8th. Beaehy Head.— 16th. 
 Atlantic, lat. 37° N.-76° W.— 21st. Atlantic, 
 from 43° to 75° W. — 22nd. Llandudno, 
 SiUoth ; Atlantic, from 58° to 68° W.— 28th. 
 Blackheath.— 30th. Atlantic, from 31° to 
 39° W., and in the south as far as lat. 39° N. 
 
 — Dec 1. Torquay. — 2nd. Torquay, Whitchurch. 
 
 1884. Jan. 17. Carlisle.— 18th. Atlantic, lat. 46° N.-46° W.— 
 
 19th. Carlisle. 
 
APPENDIX. 261 
 
 1884. Feb. 24. Stonyliurst- 
 
 — Mar. 21. Stonyhurst. 
 
 — April 2. Stonyhurst.— 14th. Atlantic, from 42° to 67° W. 
 
 —17th. Atlantic, from 41° N.-65° W.— 24th. 
 Oxford, Cambridge, Halifax, Stonyhurst ; 
 Atlantic, lat. 46° N.-39° W., and lat. 48° N.- 
 34° W.— 30th. Atlantic, lat. 41° N.-70° W. 
 
 — June 18. Atlantic, lat. 45° N.-44° W.— 22nd. Atlantic, 
 
 lat. 41° N.-66° W., and lat. 41° N.-71° W. 
 
 — Aug. 20. Atlantic, lat. 60° N.-22°W. — 31st. Atlantic, 
 
 lat. 44° N.-59° W. 
 
 — Sept. 13. Atlantic,lat.49°N.-29°"W.— 14th. Atlantic, lat. 
 
 41° N.-67° W.— 17th, 18th. Stonyhurst. 
 
 — Oct. 1. North Sea ; Atlantic, lat. 45° N.-55° W.— 3rd, 
 
 4th. Stonyhurst.— 6th. Atlantic, lat. 46° N.- 
 50° W.— 15th. Atlantic, lat. 47° N.-42° W. 
 — 16th. Stonyhurst. 
 
 — Nov. 2. Atlantic, lat. 48° N.-36° W. 
 
 — Dec. 14. Atlantic, lat. 41° N.-67° W. 
 1835. Jan. 22. Atlantic, lat. 50° N.-27° W. 
 
 — Feb. 5. Stonyhurst; Atlantic, lat. 49° N.-37° W.—Hth. 
 
 Atlantic, lat. 44° N.-59° W. 
 
 — Mar. 6, 14. Stonyhurst. — 15th. Torquay, Brighton, 
 
 Greenwich, Leicester, Halifax, Cirencester, 
 Walton-on-the-Naze ; aU the Atlantic froni 
 the Channel to 47° W. 
 
 — May 7. Atlantic, lat. 46° N.-36° W.— 10th. Amster- 
 
 dam.— 12th. Atlantic, lat. 46° N.-22° W.— 
 13th. Dubhn ; Atlantic, lat. 48°N.-46° W., 
 lat. 46° N.-20° W. and lat. 48° N.-15° W.— 
 14th. Stonyhurst. 
 
 — June 12. Amsterdam, 
 
 — July 1. Leicester.— 9th. Atlantic, lat. 60° N.-22°W.— 
 
 11th. Atlantic, lat. 49° N.-40° W.— 21st. 
 Leicester, Carlisle. — 22nd. Carlisle. — 27th. 
 Leicester. 
 
 — Aug. 13. Stonyhurst.— 28th. Atlantic, lat. 50° N.-32° 
 
 W. 
 
 — Sept. 2. Atlantic, lat. 47° N.-51° W.— 3rd. Atlantic, 
 
 lat. 45° N.-55° W.— 4th. Atlantic, lat. 40° 
 N.-70° W.— 6th. Atlantic, lat. 39° N.-70° W. 
 — 11th. Stonyhurst. — 14th. Atlantic, lat. 
 44° N.-60° W.— 15th. Atlantic, lat. 49° N.- 
 37° W. 
 
 — Oct. 8. Atlantic, lat. 47° N.-42° W.— 12th. Atlantic, 
 
 lat. 47° N.-47° W.— 14th. Atlantic, lat. 48° 
 
262 THE POLAE ATJEOEA. 
 
 N.-42° W.— 15th. Atlantic, lat. 47° N.-4 ' 
 W. and lat. 51° N.-22° W. 
 
 1885. Nov. 7. Atlantic, lat. 44° N.-52° W. and lat. 49° N.-2y° 
 
 W.— 9th. Atlantic, lat. 44° N.-55° W. and 
 lat. 47° N.-45° W.— 10th. Atlantic, lat. 48^ 
 N.-37° W. 
 
 1886. Jan. 9. Torquay.— 21st, 29th. Kcenigsherg. 
 
 — Peb. 20, 21. Kcsnigsberg. 
 
 — Mar. 3, 14. Kcenigsherg. — 30th. Yebleron, Eolleville 
 
 (Seine-Inf.),la Mothe-Achard (Vendee), west 
 
 of France ; Dublin, Eamelton, Kingstown ; 
 
 Magdeburg, Greifswald, Greifenberg, 
 
 Kcenigsherg. 
 Liverpool; Kcenigsherg. 
 Dax. — 27th. Torquay, Paisley, Gilsland, 
 
 Eamelton (Ireland) ; Kcenigsherg. — 30th. 
 
 Kcenigsherg. 
 Kcenigsherg. 
 Kcenigsherg. 
 
 1887. Feb. 12. Bothkamp.— 14th. Kcenigsherg. 
 Stonyhurst. — 20th. Kcenigsherg. 
 Kcenigsherg. 
 
 Kcenigsherg.— 25th. Atlantic, lat. 47°N.-33° W. 
 Atlantic, lat. 49° N.-15° W.— 19th. Atlantic. 
 
 lat. 41° N.-69° W.— 24th. Kcenigsherg. 
 
 — Aug. 29. Atlantic, lat. 47° N.-38° W. 
 
 — Oct. 27, 31. Kcenigsherg. 
 
 — Nov. 21. Atlantic, lat. 46° N.-52° W. and lat. 45° N... 
 
 48° W. 
 
 — Deo. 6. Atlantic, lat. 44° N.-57° W.— 16th. Atlantic, 
 
 lat. 50° N.-21° W., and lat. 46° N.-48° W. 
 
 1888. Jan. 13. Kcenigsherg. 
 
 — Mar. 8. Atlantic, lat. 44° N.-55° W., and lat. 54° N.-27° 
 
 W.— 15th. Atlantic, lat. 46° N.-38° W. and 
 lat. 42° N.-56°W.— 29th. Kcenigsherg. 
 
 — Apr. 2. Kcenigsherg; Atlantic, lat. 55° N.-27° W.— 8th. 
 
 Kcenigsherg. — 11th. Atlantic, lat. 46° N.- 
 42° W., and lat. 48° N.-31° W. 
 
 — May 6. Eock-Ferry (near Liverpool). — 7th. Atlantic, 
 
 lat. 40° N.-72° W. — 11th. Atlantic, lat. 
 46° N.-42° W.— 20th. Atlantic, lat. 44° N.- 
 52° W.— 28th. Kcenigsherg. 
 
 — July 7. Atlantic, lat. 47° N.-33° W. 
 
 — Aug. 3. Atlantic, lat. 47° N.-44° W. 
 
 — Sept. 7. Atlantic, lat. 42° N.-67° W., and lat. 44° N.- 
 
 55° W.— 9th. Atlantic, lat. 42° N.-64° W.— 
 
 Apr. 
 July 
 
 11. 
 12. 
 
 Nov, 
 
 2. 
 
 Dec. 
 
 25. 
 
 Feb. 
 
 12. 
 
 Mar. 
 
 15. 
 
 Apr. 21. 
 May 17. 
 June 18. 
 
APPENDIX. 263 
 
 26th. Atlantic, lat. 50° N.-32° W.— 28tli. 
 Atlantic, lat. 58° N.-9° W. 
 
 1888. Oct. 2. Atlantic, lat. 54° N.-34° W.— 5th. Atlantic, lat. 
 
 41° N.-70° W., and lat. 46° N.-48° W.— 8th. 
 Atlantic, lat. 58° N.-37° W., and lat. 53° N.- 
 43° W.— 10th. Atlantic, lat. 48° N.-40° W.— 
 11th. Atlantic, lat. 50° N.-32° W. — 19th. 
 Atlantic, lat. 45° N.-57° W.— 26th. Kcenigs- 
 herg.— 30th. Atlantic, lat. 52° N.-65° W.— 
 31st. Atlantic, lat. 61° N.-27° W. 
 
 — Nov. 1. Atlantic, lat. 49° N.-36° W.— 4th. Koenigsberg ; 
 
 Atlantic, lat. 50° N.-25° W.— 6th. Atlantic, 
 lat. 44° N.-55° W.— 9th. Atlantic, lat. 50° N.- 
 19° W.— 26th. Atlantic, lat. 48° N.-42° W. 
 
 1889. Feb. 19. Atlantic, lat. 45° N.-48° W. 
 
 — Mar. 5. Atlantic, lat. 43° N.-57° W. 
 
 — April 8. Atlantic, lat. 46° N.-40° W.— 25th. Atlantic, 
 
 lat. 47° N.-44° W., and lat. 48° N.-46° W. 
 
 — Sept. 15. Atlantic, lat. 46° N.-51° W. 
 
 — Oct. 19. Atlantic, lat. 43° N.-65° W. 
 
 — Nov. 1. Atlantic, lat. 44° N.-56° W.— 26th. Halifax; 
 
 Atlantic, lat. 47° N.-46° W., and lat. 56° N.- 
 25° W. 
 
 — Dec. 27. Atlantic, 500 miles to the east of Cape Bace. 
 
 1890. Jan. 27. Halifax. 
 
 — July 16. Atlantic, lat. 52° N.-58° W.— 23rd. Atlantic, 
 
 lat. 50° N.-46° W. — 28th. Atlantic, lat. 
 52° N.-56° W. 
 
 — Aug. 14. Atlantic, lat. 40° N.-73° W.— 15th. Atlantic, 
 
 lat. 49° N.-39° "W. — 16th. Atlantic, lat. 
 48° N.-45° W.— 18th. Atlantic, lat. 45° N.- 
 55° W. 
 
 — Sept. 3. Atlantic, lat. 44° N.-59° W.— 10th. Atlantic, 
 
 lafc. 46° N.-53° W., and lat. 46° N.-55° W.— 
 11th. Atlantic, lat. 49° N.-37° W., lat. 52° N.- 
 56° W.,lat. 45° N.-59° W., lat. 44° N.-63° W. 
 and lat. 40° N.-67° W.— 12th. Atlantic, lat. 
 50° N.-21° W., lat. 50° N.-30° W. and lat. 
 53° N.-51° W.— 13th. Atlantic, lat. 55° N.- 
 45° W.— 15th. Atlantic, lat. 50° N.-39° W. 
 and lat. 46° N.-42° W.— 19th. Atlantic, lat. 
 43° N.-62° W. 
 
 — Oct. 5. Atlantic, lat. 49° N.-86° W., lat. 49° N.-38° W., 
 
 lat. 45° N.-54° W., and lat. 40° N.-69° W.— 
 11th. Atlantic, lat. 44° N.-60°W.— 14th. At- 
 lantic, lat. 51° N.-30° W.— 17th. Atlantic, 
 
264 THE POLAR AUEOEA. 
 
 lat. 44° N.-50° W. — 18th. Atlantic, lat. 
 49° N.-19° W. 
 1890. Nov. 7. Atlantic, lat. 42° N.-67° W. and lat. 40° N.- 
 70° W.— 8th. Atlantic, lat. 44° N.-60° W.— 
 13th. Atlantic, lat. 61° N.-23° W. and Iftt. 
 50° N.-36° W. 
 
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