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Jz/ttrur % ^'C&^r'r-d ', ^ Oc*i>^/b 0^~ Go <2^2^2siJ- ifcuj l^-L^C ^0^ £> S^J^C ^Jltf djJtbcJ- ‘^to^JLl- /&^ ^ayfy t^Urwy^ftio SMa^ O^cpL 1 ^ jfot ’VTVLl x. ^ju n* u 7A^ cru tiJiA^L ocAjC oJl^ru^Cc^ 6c ^ J (Trt-r ffvLc- ^ .^ij2J~ AtAlaJLi-- f yt ojv &a 'rva, £t c&ivuM^j ^ Jy~t s eTj~, ^ hct Y^cC> o ~(fn^ c tst'iy ? •£■..•., bdtfrncolb ^pjrtcUlJu m* > U t /)t L iut- ^T ,*/i fc Ij fj- 'irt/ftstirl; ^ io-^lu^l- jLo a -'&d-' ■, C+'^/h~F/£- C/l/ r^vt l Digitized by the Internet Archive in 2017 with funding from Getty Research Institute https://archive.org/details/magiclanternhowtOOmere THE MAGIC LANTERN, IN ITS APPLICATION TO THE MODERN METHOD OF RAISING A GHOST. See page 94. THE MAGIC LANTERN HOW TO BUY AND HOW TO USE IT ALSO HOW TO RAISE A GHOST By “A MERE PHANTOM” “ If this be Magic, let it be an art Lawful as eating.” Shale spare. Cfamtfetfy Eijousantb LONDON HOULSTON AND SONS PATEBNOSTEB SQUAE^, E.C. MDCCCLXXIV. The right of translation is reserved. [Entered at Stationers’ Hall.] London: J. & W. Rider, Printers, Bartholomew Close. CONTENTS. PAGE Aphengescope . . .49 Argand Oil Lamp . . .23 Astrometeoroscope . .61 Apparatus, Dioptric Dissolving 91 Apparatus, Dissolving . .78 Apparatus for making Oxygen 27 Apparatus for making Hy- drogen . . . .37 Chapter for Children . .12 Chinese Fireworks . .61 Classification of Lanterns . 19 Condenser . . . .18 Conditions of Absolute Safety 42 Clockwork . . . .44 Compressed Gases . . .47 Comic Slides . . . .52 Chromatrope . . .60 Colouring Slides . . .95 Dioptric Dissolving Apparatus 9 1 Dissolving View Apparatus . 78 Dissolving Tap . . .89 Diameters of Disc. . .90 Disc Diameters (Table of) .90 Eidotrope . . . .61 Electric Light Lantern . .75 First Magic Lantern . . 8 Gas, a substitute for Hydrogen 40 Gas Bags . . . .45 Gasometers . . . .46 Gases, Compressed . .47 Ghost ..... 94 History of Magic Lantern . 9 Hydrogen, Preparation of . 36 India-rubber Tubing . . 41 Kaleidoscope for Lantern . 71 Lever Slides . . . .57 Lime Cylinders (to make) . 39 Lecturer’s Sundries . . 92 Magic Lantern, The first . 8 Magic Lantern, its History . 9 Microscope Lantern . .67 Microscope, Oxyhydrogen . 75 Magnesia Cylinders . . 39 Moving Waters . . .62 Oxygen, preparation of . .29 PAGE Oxygen, eight methods to prepare . . . .28 ,, compressed . . 47 ,, Test for purity of mixture . . . .31 Oxycalcium Light Apparatus 28 Oxyhydrogen Safety Jet . 34 Oxyhydrogen Light . . 35 Opaque Lanterns . . .48 Object Glass . . . .18 Phantasmagoria Lantern . 17 Preparation of Oxygen . .28 Preparation of Hydrogen . 36 Purifier . . . . 27 Pressure Boards . . .32 Photographic Slides . .58 Photographs, How to take . 59 Polariscope . . . .73 Precautions for the use of Slides .... 63 Recapitulation (Oil Lantern) . 25 Recapitulation (Oxycalcium) . 34 Recapitulation (Oxyhydrogen) 44 Retort, Oxygen . . .27 Revolving Figures . .62 Screens. . . . .65 Sizes of Lanterns . . .16 Safety Valves . . .41 Safety, conditions of absolute 42 Slides, general precautions . 63 „ Astronomical . .52 ,, Comic . . .52 ,, Lever . . .57 ,, Natural History . 52 „ Slipping • • • 55 ,, Photographic . .58 „ Snow . . .84 ,, Smoke . . .82 Sapphire and Ruby Glass . 86 Stereoptikon . . . 81 Table of Disc Diameters . 90 Test for Oxygen Mixture . 31 Verandah Slide . . .93 Wonder Camera . . .49 Zirconia Cylinders . . 39 Q.IXA, 50 AD VERTISEMENT. The following pages have been written as a “ Handy Guide ” for those desirous of amusing the younger members of a family, or imparting instruction to a class at school; all technical terms which could be dispensed with have, therefore, been carefully excluded. * The increased use of the Magic Lantern as a means of beguiling the long evenings of winter, and the absence of any book on the subject, render a brief and simple guide for the unscientific purchaser not only desirable, but necessary. The high position now accorded to this instrument may be inferred when it is remembered that the Secretary of State for War has issued a circular, providing for a sunply of Magic Lantern slides to illustrate lectures to the soldiers in our Army; nor is our Navy left without similar resources of recreation and instruction. Scarcely anything could be devised so likely to awaken the minds and fix the attention of those for whom the lectures are prepared, as these viva voce addresses, and appeals to the eye through the agency of the Magic Lantern. It is also a very suggestive circumstance that Hr. Livingstone took with him a Magic Lantern to instruct and amuse the natives of the countries he visited ; and in an interview with Sir Samuel Baker, the writer was informed that he too, “though bent on such high embassy,” would carry a Magic Lantern with him for the entertainment of swarthy Nubians, so that while naturalized in London, the centre of the world’s civilization, the Magic Lantern is no stranger to the dusky denizens of the heart of Africa. The increasing popularity of the Stereoptikon in America will suggest the usefulness of this “ guide ” to our cousins on the other side of the Atlantic. In sending forth this enlarged edition, the writer desires to acknowledge valuable assistance received from the editor of the British Journal of Photography , and from the publisher of the same journal, to whom he is indebted for the loan of numerous cuts which embellish the work ; from Messrs. Longman and Co., who furnish the illustrations of Du- boscq’s Electro-light Apparatus on pp. 75 and 76 ; from their excellent translation of “ Ganot’s Physics ;” from Messrs. Sampson Low and Co., who supply from their “Wonders of Optics” the admirable illustra- tions which form the frontispiece and appear at p. 12 ; from the artist furnishing the engravings, who, himself an expert in the use of the Magic Lantern, has worked con amore at the woodcuts, and a description of whose dissolving tap appears at p. 89 ; and from the Society for Promoting Christian Knowledge in illustrations from the “Wonders of Light and Shadow.” Nor must the writer omit to acknowledge the courtesy of numerous firms in the Optical and Scientific Instrument Trade, to whom he is indebted for the loan of cuts illustrating various forms of Magic Lanterns and Apparatus connected therewith. The leading organs of the literary and scientific Press having given most favourable opinions on the merits of the earlier editions, and the principal Opticians of our country having adopted the Manual as a Guide to the Use of the Magic Lantern, the author is encouraged to hope that this further enlarged and improved edition may be found even more solidly useful, though still only the production of “A MEKE PHANTOM.” THE MAGIC LANTERN. HOW TO BUY IT. Fig. 1.— THE FIRST MAGIC LANTERN. The Magic Lantern, which three centuries since served no better purpose in the hands of pretended wizards and necromancers than to induce a belief in their possession of supernatural powers, now occupies a deservedly high position as a Scientific Instrument, capable of affording rational amusement to the young, instruction to “ children of a larger growth/' and in the hands of the philosopher, a means of demonstrating some of the most beautiful phenomena in science. By Its means the monotony of “ evenings at home ’’ 8 THE MAGIC LANTERN. Las been charmed away ; new ideas have been intro- duced, fresh mirth inspired, and useful instruction gained. How delightful is one of those gatherings, where youth, infancy, and maturity are, for different reasons, equally interested in the mimic scenes so vividly pre- sented ! infancy charmed with the rapid change of form and colour and grotesque fun, and its infectious laughter echoed by young and old. Notwithstanding the general diffusion of scientific knowledge, few are accurately informed as to the method by which such charming effects are produced ; and it is the object of the present treatise to offer such information in a compendious form. Page 7 bears a representation of the cumbrous and imperfect apparatus which created so great a sensation in Pome in the seventeenth century, the description * of which suggests the thought that if those who witnessed the first rude phantasms it threw out could see one of our refined modern exhibitions, their surprise would be little less than that which was excited by the imperfect outlines on the walls of Kirch ers chamber. It consisted of a large square wooden box, with a door at one side, and an opening into which a lens in a tube was fitted, at the other. The source of light was an oil lamp ; but furnishing a flame of so smoky and dingy a character that it was but slightly im- proved by the use of a polished brass reflector, intro- duced by Kircher, with the view of concentrating the rays upon the lenses. The whole lantern appears to have been of very large size ; if the drawings are to * “Wonders of Light and Shadow.” THE MAGIC LANTERN. 9 be relied on, not less than six feet square. The mag™ nifying power employed was probably very low. In writing of the modern instrument, Sir David Brewster says, “ The Magic Lantern, which for a long time was used only as an instrument for amusing children and astonishing the ignorant, has recently been fitted up for the better purpose of conveying scientific instruction, and it is now universally used by popular lecturers on Astronomy for representing the phases and the motions of the heavenly bodies, all of which are minutely painted on the slides. “The Magic Lantern may be employed in almost every branch of scientific instruction where it is desirable to give a distinct and enlarged representation of phenomena to a public class. The lecturer is thus saved the trouble of carrying about with him unwieldy diagrams, which are soon destroyed by use, and rendered unfit for their intended purpose/' In general terms, a Magic Lantern may be described as an optical apparatus, furnished with lenses, for the purpose of projecting on a wall or screen enlarged images of transparent objects placed before it. Its invention is ascribed to Roger Bacon, about A.D. 1260, but more correctly to Athanasius Kircher, who died in 1580. Figures 2 and 3 are illustrations of the simplest form of Magic Lanterns, fig. 2 giving a general view of the instrument, and fig. 3 showing the same apparatus in section. Those numbered in most Opticians’ catalogues from 1 to 6 are of the simplest construction, both condenser and object-glass consisting of a single lens. 10 THE MAGIC LANTERN. The following is a list of the Magic Lanterns found at Opticians' shops, of a kind best adapted for the Fig. 2. Fig. 3. amusement of children at a juvenile party. They are usually sold at prices varying from five to fifty shil- lings, and the description contained in this list will enable any purchaser to indicate to a salesman the kind of lantern he requires. Diam. of Focus of Object Distance Yields a disc condenser. Glasses. from screen. diam. of If inch. 2f inch. .. 4 feet. 3 feet. 1 ^ 1 4 ,, 2f „ 5 „ ... 4 „ *2 3f » Of „ ... 5 „ 2f >» 3 „ 8 „ ... 0 „ 3 r) 43 . “ 8 J > •' 10* „ ... 8 „ 3 ,, Q3 ,, . 10f „ ... 8 „ 3f ? j QJL >1 .. 14 „ ... 10 „ For Parlour or Drawing-room Phantasmagoria, the lantern may be conveniently placed on the box sup- plied with it, and the whole elevated on a small four- * No. 3 is the first size of the smaller Lanterns which (being fur- nished, like the larger ones, with a spring to hold the slides) admits of the use of small Chromatropes (page 54), Changing Comic Slides (page 50), small Lever Slides (page 51), and 2-inch Views and Photo- graphs on separate discs of glass. THE MAGIC LANTERN. 11 legged deal dressing-table, such as usually supplied for a servant's bedroom. This will raise the centre of the lantern between four and live feet high, thus admitting of the production of an 8 or 10-feet disc, in a room having a height of 10 or 11 feet. Figs. 1 and 2 show that the lantern is so constructed as not to admit any light into the room except that which passes through the picture ; and in order that this may be strongly illuminated, a concave reflector is placed behind the lamp, to throw back all the light which radiates in that direction. The lanterns usually supplied in the shops may be divided into three classes, viz., those intended to be illuminated by oil, those for the oxycalcium, and those for the oxyhydrogen light. The first class, on account of the moderate prices of the smaller sizes, are bought in large numbers for the amusement and instruction of the “ little ones ; " the consideration of which brings us to our — Chapter for Children. Most loving fathers will remember how the heavy labours of the day have been lightened by recalling the bright faces of George and Florence at home ; and when the birthdays and Christmas-tides come round, Paterfamilias may be seen smiling through the dreari- ness of London fogs or country mists, as he anticipates Lilian’s laugh and Gertrude's crow when he exhibits that Magic Lantern which he has determined to buy ; and though chained to “ desk's dead wood,” thought is free, and suddenly his spirit is far away. He sees his little drawing-room brilliantly lighted, and his family THE EVENING PATTY. • See page 8. THE MAGIC LANTERN. 13 brilliant too, with smiles and gaiety ; the wondrous sheet is suspended, the lantern fixed, the children sit- ting round, — he fancies even his own deep bass, com- mencing with “View of the Temple of the Sun at Baalbec" — when a mild tenor interposes with “Cheque upon Barclay, sir and lo ! the dream is dispelled, his spirit returns, and the fog is visible again. But there is a light behind it — the light of love, — and papa says in- wardly, “ They shall have a lantern ; " and business being over, he goes to the nearest Opticians, and with a cheerful spirit launches out his sovereign, more or less, receiving in exchange a neat brown paper parcel ; calls a cab, and triumphantly drives away with his treasure. The parcel is laid on the table, and excites the curiosity of the young folks. “What ever can it be?" says Florence. “ What a funny shape ! " says Edith ; and the impetuous George, impatient of the string, is snubbed for rushing to his mammas workbox for scissors. At length the paper is removed, and the lantern stands revealed in all the jetty brilliancy of black japan. “Well," says papa, “what shall we do first?" “Stick up the sheet," says one. “Light the lamp," says another. “Ah ! but what about the oil?" says mamma. “ The very thing I have forgotten," says papa. The first thing done, therefore, by Paterfamilias will be to send for some of the best sperm oil.* Having obtained this, he should gently warm a por- tion on the hob in the lamp near the fire, and then * Solid Paraffin yields a light of equal brilliancy to the campho- rated oil. It is melted by a gentle heat, by placing the lamp containing it on the hob of a grate ; when, however, the first charge is exhausted, it involves the slight inconvenience of melting some more paraffin in a separate vessel before it can be poured into the lamp. 14 THE MAGIC LANTERN. pour into the lamp a sufficient quantity to nearly fill it. With the Magic Lantern he will doubtless have obtained from the Optician a piece of cotton wick, of a size properly suited for it. This should be made quite dry by holding it for a while before the fire. It may then be passed through the wick-liolder, which has, of course, previously been unscrewed. A scissors will now make the wick of a length suitable for the size of the lamp, after which the whole is placed in the ring at the top of the lamp. (See fig. 3.) This being done, the scissors will again come into use, and this time they should be very sharp, so as to cut the wick very neatly, and without a jagged edge, and not so close but that a portion protrudes through the wick-holder. The great element of success is the obtaining of a CLEAR AND BRILLIANT LIGHT FREE FROM SMOKE ; and this depends mainly— on having good oil slightly warmed, the neatness with which the wick is trimmed, and the amount which is allowed to project beyond the wick-holder ; observing also to allow sufficient time (say five minutes) for the complete saturation of the wick by the oil. The reflector attached to the lamp should be quite bright. To this end it should be polished with any material free from grit. That found handiest in most households is a little whiting and water, or oil, which, rubbed over by the finger or a piece of linen rag, and polished dry with a chamois leather, will generally accomplish the end in view. Rouge, rotten- stone, or Tripoli may also be used. The object-glass and the condenser, or, in other and simpler words, the front and back lenses, now claim THE MAGIC LANTERN. 15 attention. In the smaller sizes of lanterns, to which these remarks are intended specially to apply, they simply require to be removed from their places very carefully, polished with a chamois leather, and replaced. It is only necessary now to light the lamp and place it, when kindled, inside the lantern, and close the door, and the lantern is ready for use. Before inserting any of the slides, it is necessary to have a suitable surface on which to project the pictures to be exhibited. This may be contrived by stretching a linen or calico sheet, as free from folds as possible, on the wall, or pinning it to the window-curtains. Such operations involve a slight disturbance of do- mestic arrangements, e. g., unhanging pictures, &c., and elicit decided objections from Materfamilias, in which case a very convenient screen for the smaller lan- terns may be made by stretching a piece of linen over an ordinary child's hoop of three or four feet in diameter. On turning the lantern containing the lighted lamp towards the screen, there will be observed, not only an indistinctness of outline at the margin, but dark spots in or about the centre of the disc of light. The reined}", in the first case, is to turn the sliding tube in the front of the lantern in or out, until the desired sharpness is obtained ; in the second case the dark spots will disappear on moving the lamp nearer to or farther from, and from right to left of the centre of the condenser. In some of the smaller sizes of lanterns (from No. 4 upwards) this adjustment is made in the course of manufacture, and a suitable recess provided, in which it is only necessary the lamp should be placed as soon as trimmed and lighted. 16 THE MAGIC LANTERN. A clear disc of light having been obtained, the slides should be carefully dusted before being placed in the lantern, and each picture accurately centred and focused until a clear outline is obtained upon the screen. A piece of wood, cut as shown at No. 21, fig. 58, page 92, will be found very useful to elevate the slide, and thus bring the picture in a line with the centre of the condenser. The optical centring of the components of a Magic Lantern is illustrated by fig. 42, page 69, where the dotted line cuts the source of light, the con- densers, the object, and the object-glasses. If a good result be desired, this point requires attention. Fig. 5. Fig. 6. Fig. 7. The Phantasmagoria Lantern. HOW TO BUY IT. The Lanterns classified under this head are usually of large size, and made of japanned tin, as are the THE MAGIC LANTERN. 17 smaller ones, but sometimes of mahogany, lined with sheet iron; and so long as they bear outside evidence of being substantially made, the purchaser may rely for their durability upon the reputation of the house at which he makes the purchase. The condensers and object-glasses, however, being the parts upon which the success of an exhibition mainly depends, may undergo at the hands of the pur- chaser a more rigid scrutiny than the mere body. These essential portions of the apparatus are liable to three defects, viz., scratches, air-bubbles, and strisa, the influence of either of which on the success of the exhibition depends upon whether they are in the con- denser or the object-glass. o Fig. 8. C In examining the larger sizes of lanterns, a purchaser is apt to be hypercritical in relation to spots or air- bubbles ; he should therefore bear in mind that the quality of a condenser is not so important for large oil flames, in which the source of light is of extended area, as for oxycalcium and oxyhydrogen, where the light emanates from a point ; and for these, attention to the following brief statements will save much time : — 18 THE MAGIC LANTERN. 1. Object-Glass, or Magnifying Lens. — 0, fig. 8 ; an air-bubble, scratch, or spot on the object-glass is of small importance, its effect being merely to intercept an infinitesimal portion of light ; but striae in the object-glass may not be so lightly passed over, since the effect of these is to confuse the image. 2. Condenser, or Bull's-Eye. — C, fig. 8 ; it is more important that an air-bubble, scratch, or spot should be absent from a condenser than an object-glass, since, if present, an enlarged image thereof will be reproduced upon the screen (if in the biconvex lens) ; while striae, which are so deleterious in an object-glass, are here of comparatively small importance. It will be obvious that the defects above referred to would be better absent, both from condenser and object-glass ; but as the perfection of construction which obtains in a portrait or microscope lens is neither aimed at nor necessary in lantern lenses, it would be simply puerile to reject or abstain from purchasing on account of a small defect which — according to its nature and locality — produces no ill effect, and if required in every instance to be absent would probably double the price of every lantern. When the purchaser, besides desiring a magic or phantasmagoria lantern for amusing the younger members of his family, wishes it to answer the more exalted purpose of conveying instruction to a class of Sunday school children, or to illustrate an amateur- lecture, he becomes sometimes perplexed by the varying sizes and prices in an Opticians catalogue. Attention to the following particulars will aid in making the selection. THE MAGIC LANTERN. 19 * The classification of lanterns referred to at page 11 may be more precisely described as follows : — 1st, Children's, or Toy Lanterns, having simple condensers, varying from 1J to 3J inches in diameter. 2nd, Phan- tasmagoria Lanterns, having double lens condensers, from 3 to inches in diameter, for use either with the oil, oxy calcium, or oxy hydrogen light. 3rd, Phan- tasmagoria Lanterns, with double lens condensers, from 3 to 4^ inches in diameter, but with iron- lined mahogany bodies, and double achromatic object-glass with rack and pinion adjustment. Of the first class it may be said that they answer their purpose admirably well, and, when price is con- sidered, the wonder is they can be offered so low. The lanterns in the second class possess all the essentials of a good lantern, viz., double condensers and object- glasses ; and where the purchaser desires to keep within the limit of £5 or £10 for lantern and slides, he may be well assured that these will prove satisfactory purchases. The third class includes what may be regarded as finished and perfect lanterns, being fur- nished with every appliance and adjustment, besides the additional comfort of working with, or rather handling, a wood body rather than one of japanned tin. (See fig. 5.) These can be recommended as a kind of lantern which will give permanent satisfaction, prove suitable either for amusement or instruction, and serve for the oil, oxy calcium, or oxyhydrogen lights ; yielding with the first a well-illuminated disc of 10 or 12 feet in diameter, and with the latter means of illumination, discs of 20 to 30 feet. Lanterns of the kind last described are sometimes 20 THE MAGIC LANTERN. « furnished with blue discs of glass let into the doors, to enable the operator to make the necessary adjustments when using the oxycalcium or oxyhydrogen lights without injury to the sight. If these be absent he will do well to furnish himself with a pair of deep blue spectacles. The Phantasmagoria Lantern, how TO USE IT. “ What mighty magic ! ” — ShaTcspere. This high-sounding name, derived from the Greek words (pavraorfux (phantasma), a spectre, and ayapaopai (agaraoprnai), I meet, and having reference only to the manner in which the lantern is used, is applied to the Lanterns described above under the second and third divisions, which give greater flatness of field, and a more truthful delineation of the picture over the whole extent of the illuminated disc. The manner of using the Magic Lantern so as to pro- duce the effect known as the Phantasmagoria was introduced into London in the year 1802 by a French gentleman named Philipstal, who, when showing it publicly at a time when those who formed his audience were entirely ignorant of the means by which the effect was accomplished, did not fail to increase the mystery attending the exhibition by every means at his disposal. An oil lamp suspended from the centre of the room, and yielding a most dismal light, served only “to make darkness visible ; ” and even this was withdrawn as soon as the audience were seated ; so that they were surrounded by “ a darkness which might be felt,” amid which strains of music, having “a dying fall,” were THE MAGIC LANTERN. 21 heard, followed by the rumbling of distant thunder, the flashing of lightning, and other tokens of the warring elements. While this elemental strife was at its height, there appeared in the air a small disc of light, which gradually expanded, revealing to the gaze of the astonished spectators ‘‘The Phantom of the Storm/' upon whom the skies seemed to “spit fire, spout rain/' &c. The phantom “ waved its long lean arm on high," rolled its glaring eyeballs with an ex- pression of unutterable woe, suddenly retired into the darkness from whence it came, and finally vanished in a little cloud. Other spectres, with appropriate accompaniments, followed in quick succession ; some of which, rushing suddenly upon the spectators, elicited screams from the more nervous, showing that they were regarded as anything but “honest ghosts," or “ fine apparitions." The effects introduced more than half a century ago with such mysterious surroundings may now readily be produced in an ordinary parlour or drawing-room by adopting the arrangement shown in the accompany ing engraving, fig. 9. The whole picture is suggestive of “ a happy home ” and keen social enjoyment ; and the family circle, to increase which “a few friends" have evidently been in- vited, seems to enter fully into the spirit of the enter- tainment provided for them by the scientific man of the family, who, from the superior character of the fur- niture, must be assumed to be in the front parlour or drawing-room. Between this apartment and the one where the guests are assembled, it will be seen, by the tin tacks hammered into the framework of the folding- Fig. 9. — THE METHOD OF USING THE “ PHANTASMAGORIA ” LANTERN. Seepage 21. THE MAGIC LANTERN. 23 doors, that a linen or muslin screen has been stretched, upon which the phantom is projected by the lantern. The transparency of the screen has been previously in- creased by wetting , and the Magic Lantern being placed on a stand, or “what-not,” as represented in the diagram, and a piece of white tape tacked down to the door, in a direct line from the centre of the screen, to guide the operator in advancing or receding, the pic- ture is placed in the lantern. The stand bearing the lantern should then be wheeled* up close to the screen, when a bright disc of light, varying in diameter from four to eight inches, will be produced. Before focusing the image in so small a disc, a piece of crape should be dropped over the front of the lantern, so as slightly to diminish the bright- ness, as it will unavoidably become less bright as the lantern is run back- wards in the direction of the white tape. Simultaneously with the act of receding, the crape may be removed, thus compensating for the dilution of the light over a larger surface, and the consequent diminution of bright- ness. It will be understood that the object of the Phantasmagoria is to produce the idea of approaching and retiring by means of images which really only con- tract and expand ; and the disadvantage attending the operation is, that when the image is at its brightest it occupies the smallest area, and vice versa. The contrary * The wheels should move noiselessly , and should therefore be well oiled, and, if practicable, covered with india-rubber. 24 THE MAGIC LANTERN. would, of course, be the most appropriate conditions ; and hence the necessity for the employment of crape, or partially obscuring the light by the fingers, since the illusion is as much dependent on equal brightness as equal distinctness. When Sperm Oil v is used, the lamps supplied with these larger and more carefully constructed lanterns are generally of the best Argand fountain form, and the concave silvered reflectors attached thereto of large diameter and substantial material. Such a lamp is shown in the margin. A brief recapitulation will here prove useful. In the first place, it is essentially necessary that the room in which the exhibition takes place should be perfectly DARK, as any stray light is apt to mar the distinctness of the picture. A new dry wick having been attached to the brass collar furnished for that purpose, the lamp should be filled with warm Cam- phorated Sperm Oil — made by dissolving two ounces of Camphor, in small pieces, in one pint of Sperm Oil, by aid of a gentle heat, — and while sufficient time elapses for the complete saturation of the wick with oil, the lamp glass or chimney should be wiped with scrupulous care, so as to be perfectly bright and clear. The wick should then be kindled, allowed to burn for a short time, and then blown out. This makes it easier to trim the wick down to that clean level edge which is essential to the production of a bright light. After careful trimming, the wick may be re- kindled, and the lamp glass placed in the gallery around the lamp (fig. 10). The concave reflecting mirror, having been previously well polished with rouge and THE MAGIC LANTEPN. 25 chamois leather, should also he placed in position behind the lamp. While, however, the whole of the above has been going on, the condensing lenses should have been removed from the lantern and placed inside the fender in front of the fire to warm gently, so as to prevent their cracking with the heat of the lamp ; and assuming this to have been done, they should now be taken up and carefully wiped, nay, even polished, with a clean linen cloth or dry chamois leather. The same operation of wiping and polishing having been ob- served with the front lenses or object-glasses in the sliding tube, and the lamp having been placed inside, the lantern is now ready for use. Each picture, having been previously freed from dusty should now be pushed upside down into the groove provided for that purpose between the con- denser and object-glass. The wick of the lamp should now be turned up as high as possible short of smoking, and finally the focus ad- justed by turning the pinion screw or sliding tube in or out until a well-defined image is obtained on the screen. Recapitulation. From a new lamp remove all dust. From a lamp which has been used remove old oil. Dry the wick thoroughly. Warm the Camphorated Sperm Oil. Fill the oil cistern about two- thirds full. Allow wick to become saturated with oil. Light lamp, and put out after burning a minute. Now trim the wick neatly with sharp scissors. Re-light, turn wick up without smoke. Flame to be in centre of bull’s-eye and reflector. 26 THE MAGIC LANTERN. Polish reflector with rouge and chamois leather. Warm the condensers or bull’s-eyes at the fire. Wipe carefully with silk duster, and replace them. Also wipe object lens in front sliding tube. Wipe and dust pictures, and arrange them in order. Darken room. Place pictures in slide-holder upside down. Determine size of picture by distance from screen. Secure sharpness by focusing with front sliding tube. Have chamois leather and a duster always at hand. The Oxycalcium Light. “ Giving more light than heat.” — Shakspere. Hitherto it has been assumed that the means of illumination is Camphorated Sperm Oil, and when it is desired to exhibit in a drawing-room on a disc of eight feet, oil will, when properly managed, give a sufficiently brilliant light. THE OXYCALCIUM LAMP. Fig. 11. A and B are parts of the cistern for containing the Methylated Spirit, which flows through a long tube to the wick at C. Immediately under this is shown the tube which, terminating in a jet curved at a suitable angle, enables the Oxygen to be directed through the centre of the flame upon the Lime cylinder D, which has been previously THE MAGIC LANTERN. 27 placed on the holder E provided for that purpose. The screw F is to facilitate the adjustment of the lamp in relation to the centre of the lenses when in the lantern. G is the stopcock to regulate the passage of the Oxygen gas. This lamp is shown in position on the right hand of the group of Lanterns on page 16. But when with the same lanterns it is desired to exhibit in a lecture-room where a disc of twenty or perhaps thirty feet is necessary, a more brilliant source of light must be adopted. It may be observed in this place, that theoretically there is no limit to the amount of enlargement which may be effected by means of a pair of 3J-inch condensers and their accompanying object- glasses ; but practically the limit is determined by the degree of intensity of the artificial light employed, Oil bearing the least dilution, and Oxyhydrogen the most, while the same arrangement of lenses may be used in either case. For the production of the oxy cal- cium light the following apparatus is necessary : — Oxy calcium lamp, fig. 11; oxygen retort, fig. 12; oxygen purifier, fig. 13 ; oxygen gas bag, fig. 23 ; pres- sure board, fig. 15 ; connecting tube, fig. 16 ; lime cylin- ders, methylated spirit, lamp cotton, chlorate potassium, oxide manganese. The possession of these mate- rials will enable the exhibitor to commence the preparation of Oxygen gas. Oxygen may be prepared by T ^ .j / J Fig. 13.— PtJBIFIEB. heating, 1, oxide ot manganese 28 THE MAGIC LANTERN. alone, in an iron retort ; by heating mixtures of — 2, chloride of lime, peroxide of cobalt, and water ; 3, sulphate of lime and silica ; 4, oxide manganese and silica ; 5, recently burnt lime and nitrate of soda ; 6, equal parts of black oxide of copper and chlorate potash ; 7, by adding diluted sulphuric acid to a mix- ture of peroxide of barium and bichromate of potash ; 8, by heating four parts of chlorate of potash, and one part of oxide of manganese, the last named being the method almost exclusively adopted. Fig. 14. The arrangement of the apparatus is shown in fig. 14 ; the actual distances of each piece from the other may be varied, according to circumstances, by lengths of Caoutchouc tubing. The retort in this illustration is globular in form and made of copper, while the purifier is of glass. The argand burner may be advantageously replaced by a Bunsen’s wire-gauze burner, which yields a blue lam- bent flame of great heating power. THE MAGIC LANTERN. 29 A mixture of four parts of Chlorate of Potash in crystals, as usually supplied at the shops, with one part of powdered black Oxide of Manganese, is now made. In the preparation of this mixture, which is best done on a large sheet of brown paper, with a bone spatula or knife, care should be taken to avoid the accidental introduction of small fragments of straw, twine, paper, or other organic matter. As soon as every beautiful white crystal of the Chlorate of Potash is made a dirty black by the Manganese the mixture may be considered complete. The top of the retort (fig. 12) being unscrewed, two pounds of the mixture are introduced through the wide neck ; and in order that when replaced the top may fit so accurately as to prevent the escape of Oxygen, the neck should be carefully wiped from fragments of the oxygen mixture before screwing on the top. This being done, and the connections being made in the manner shown in fig. 14, the retort is placed on a moderate fire. In a short time bubbles will be heard passing through the water which has been previously placed in the purifier (fig. 13) ; but as the first portions which come over will not be pure Oxygen, but will contain a large admixture of air, the connection with the gas bag should not be made until pure Oxygen is being evolved.* This may be ascertained by lighting a piece of * * Theoretically, one pound of Chlorate of Potash should yield five cubic feet of Oxygen; in practice, however, more than four feet are seldom obtained ; hence, a quarter of a pound may he regarded as yield- ing one cubic foot. A little more might he obtained by powdering the Chlorate of Potash, but it is not so safe as heating the unpowdered crystals. 30 THE MAGIC LANTERN. brown paper, blowing it out, and bolding the still smouldering or incandescent portion in such a way that the gas from the connecting tube may play upon it ; if pure Oxygen be coming over, the paper will be “ again relumed/' and burst into flame. Some samples of Chlorate of Potassium, when undergoing de- composition by heat in this way, liberate traces of free Chlorine, the passage of which into the gas bag may easily be arrested by dissolving in the water placed in the Purifier a dessert-spoonful of Salt of Tartar, i. e ., Carbonate of Potassium. Oxygen thus freed from Chlorine becomes less corrosive in its action on the India-rubber Gas Bags or their brass stopcocks. Previous to making the final connection with the oxygen tube, the bag should have been rendered soft and flexible by warming, and rolled to expel all atmo- spheric air. When the retort is placed on an ordinary fire, it not unfrequently happens that, owing to the too intense heat, the Oxygen comes over too rapidly, and not only is some of the powder of Manganese carried from the retort into the purifier, but the mechanical action of the bubbles of gas in the purifier causes the projection of minute particles of water through the connecting tube into the gas bag ; this may be avoided by occasionally lifting the retort from the fire to the hob ; also by keeping the gas bag higher than the purifier while collecting the gas. As soon as sufficient gas has been collected to distend the gas bag to an almost drum- tightness, the stopcock S is turned off, and that end of the India-rubber tubing connected with the side or exit tube G of the purifier D is detached, and then connected with the end 0 of THE MAGIC LANTERN. 31 the Oxy calcium Lamp (fig. 11), near the stopcock. Previously to this, however, the filled gas bag should have been placed between the pressure boards, fig. 15, and the necessary weights placed in position on the top, whence they are prevented from slipping by the cross-rail C. The exhausted oxygen mixture should now be washed out freely with hot water, and the retort dried, ready for the next occasion. Test for Purity and Safety of Oxygen Mixture. Oxygen mixture is supplied ready made, and although oxide of manganese is very cheap it becomes sometimes contaminated with lamp-black and other substances of a kindred nature, which, when heated with chlorate of potash, produce explosive effects. Fig. 15. These and their attendant dangers may be certainly avoided by first making the following simple test : — Into a glass test-tube § inch in diameter and 4 inches long, introduce 10 grains of the suspected mixture, and apply the heat of an ordinary spirit lamp to Bunsen’s burner. If it be pure, oxygen gas will be quietly evolved, accompanied by a few brilliant sjfarks passing to and fro within the tube. If, however, it 32 THE MAGIC LANTERN. contains only ten per cent of lamp-black, soot, black- lead, or other carbonaceous matter, an explosion, violent in proportion to the quantity of the material and the resistance to be overcome, will be the result. It is a good plan when once fully satisfied of the purity of the sample of the mixture, to purchase fourteen or twenty pounds, and to save the residuary oxide of manganese from each operation. When the whole has accumulated in an old pan or tub devoted to the Fig. 16 . purpose, it may be collected by straining through calico, washed from the chloride of potassium, dried, and used again, ad infinitum. The form of the gas bag and pressure board will naturally suggest that the stopcock of the former is to be drawn through the opening 0 of the latter, between the hinges. Fig. 16 represents a form of Pressure Board and arrangement of gas bags which is found exceedingly useful in working the oxyhydrogen light. The advantages are, greater equality of pressure, the dis- THE MAGIC LANTEBN. 33 pensing with half the weights, the smaller space occu- pied, and the slope given to the bags carrying any water accidentally introduced away from the stopcock to the larger end of the bag. The elasticity of the contained gas gives the bags a tendency, when thus placed one over another, to spring out from the pressure boards : to prevent this a piece of sailcloth should be placed between them. The cistern A B, fig. 11, having been filled with spirit, and the wick-liolder charged with sufficient wick — about two or three inches in length, — the lamp is lighted ; but before turning the stopcock G, which admits the Oxygen, the wick should be so trimmed and disposed right and left of its Centre that none of the threads shall project towards the oxygen jet or the lime cylinder. The stopcock may now be turned on, and as soon as the lime cylinder “ warms to its work/ 5 which will be in a minute or two, a most brilliant light will be produced. The only precaution necessary to be observed in this place is that the Oxygen should work silently , and not be allowed to rush through the tube with such force as to make a singing noise. In order that this may be so, it is advisable not to begin with a greater pressure than a quarter of a hundredweight, which may be gradually increased to double that amount. No anxiety need be entertained about the bursting of the bags by increasing the pressure within reason- able limits, as good new gas bags of caoutchouc will stand a pressure of five hundredweight. A more modern, and exceedingly convenient form of jet, is that shown in fig. 17, in which the cistern for c THE MAGIC LANTERN. 34 spirit is entirely dispensed with, and replaced by an extra tube and stopcock for conducting ordinary coal gas (carburetted hydrogen) into the vicinity of the lime cylinder. It is, in fact, a simple modification of the oxy hydrogen jet, and may be regarded as absolute^ safe. The method of using consists in simply igniting the gas at the point of exit E ; and when it has burnt a sufficient time to warm the lime cylinder, and thus prevent its cracking, the stopcock 0 is turned to admit the Oxygen, as in the case of the oxycalcium spirit lamp. There are numerous advantages attached to this form of light, not the least of which is its economy, gas being cheaper than spirit, and no extra Fig. 17.~Safety Oxyhydbqgek Jet. gas bag being required. The pressure “from the main" being usually sufficient, it is only necessary to attach a piece of tubing to the chandelier, and regulate by the stopcock. Recapitulation. Cistern to be charged with half a pint of spirit. Wick, when trimmed, to project \ in. above tube. From 28 lbs. to 56 lbs. to be placed on the oxygen bag. Turn the tap connected with the bag “full on." Turn the tap near the lamp gradually on. Regulate quantity and force of gas to size of flame. THE MAGIC LANTERN. 35 An excess of Oxygen cools lime and lessens light. A deficiency of Oxygen also entails loss of light. Too much pressure also diminishes light. Keep lime cylinders carefully corked up from the air. If the gas bag be stiff, place in warm room to soften. Expel air at stopcock by rolling bag before filling. Empty gas bag at close of entertainment. The Oxyhydrogen Light. “ More light and light it grows.” — ShaJcspere. This light emanates from a cylinder of lime, ren- dered white-hot by a mixture of Oxygen and Hydrogen gases, projected thereon in a state of combustion. The lime cylinder is mounted in this instance, as in the case of the oxycaleium, so as to occupy the place of the lamp flame in an oil lamp, in relation to the con- densing lenses of the lantern. It will be naturally inferred that, although the lime cylinder seems to be burning, it does not undergo actual combustion ; but as the mechanical action of the current of mixed gases in flame has the effect of wearing it away, it is advisable, where an exhibition is continued for any length of time, to mount the cylinder holder in connec- tion with Clockwork, by means of which it is kept slowly revolving, and thus different parts of the sur- 36 THIS MAGIC LANTERN, face are successively presented to the action of the heating jet of flame. The apparatus and materials necessary for the exhi- bition of pictures by this intensely brilliant light are enumerated in the following list, which will be found useful for reference : — Apparatus and Materials for Ox yhydrogen Light. Oxyhydrogen jet. Lime cylinders. Oxygen retort. Oxide manganese. Ditto purifier. Chlorate potassium. Ditto gas bag. Hydrogen generator. Ditto purifier. Two pressure boards. Connecting tubes. Granulated zinc. Sulphuric acid. India-rubber tubing. Hydrogen gas bag. Blue spectacles. In working the apparatus the production of a full supply of gas first claims attention. The preparation of Oxygen has already been treated of; it remains therefore to describe the Preparation of Hydrogen Gas. Hydrogen, one of the constituents of water, is produced by decomposing that fluid with Zinc and Sulphuric Acid. It is an inflammable gas, much lighter than atmospheric air. The apparatus employed is shown in fig. 19, the gas bag being drawn much smaller in proportion to the other apparatus than it is in reality. A few hours before generating the gas, a mixture of one part of strong Sulphuric Acid (oil of vitriol) and seven parts of water is made. Considerable heat is pro- duced in making the mixture, and for this reason it should be made beforehand in an earthenware, not a glass vessel, so as to allow sufficient time for it to THE MAGIC LANTERN. 37 become cool before being added to the granulated Zinc contained in the generator A. About half a pound of Zinc is introduced into the generator (usually made of lead, but sometimes of glass), the top of which, bearing the tube funnel and bent exit tube, is then replaced, and the joint being made airtight (in the case of a leaden generator by means of a screw, and in the case of a glass bottle and cork by means of linseed meal luting), the diluted acid is poured down the long tube funnel B, the end of which descends far enough into the liquid to prevent the return of gas in that direction. A brisk action ensues, the gas effervescing like so much soda water. The first portions must, however, be allowed to escape for some minutes, to expel the air* * In applying a light to ascertain if pure Hydrogen he coming oyer, a piece of wire gauze, haying about the same number of meshes as common net, held oyer the aperture, will afford absolute safety from explosion. 38 THE MAGIC LANTERN. Where the precaution of diluting the sulphuric acid . and allowing the mixture to cool has been neglected, and sufficient time cannot be allowed for the purpose, the Zinc and Water may be placed in the generator, and the .concentrated acid slowly poured down the tube funnel as it is required. It is equally important that, before collecting the gas, the bag in which it is to be received should be pressed quite flat, or rolled with the stopcock open, so as to exclude all trace of atmospheric air. The time when pure hydrogen is coming off may be known by the rapid rise of the bubbles to the top of the water, and by the accompanying sound, which the ear will recognise, after a little practice, as being unlike that of other gases. The purifier C should be about half filled with water ; and connection being made between the exit tube E and the gas bag by means of india-rubber tubing, as shown in the cut, be careful to turn on the stopcock D, in order that the gas may have free entrance into the bag. (It may seem almost super- fluous to mention such a point, but experience has shown that it is just such trifles as this which get overlooked in the excitement of work, and anxiety that everything should go right). D, fig. 11, is a lime cylinder, which will be seen to be furnished with a hole in its axis, through which the wire holder is passed. Such cylinders are turned out of unslacked lime, and having a strong affinity for moisture, they will slack and crumble to pieces spontaneously if left exposed to the air ; the cork, therefore, should not be left out of the bottle, nor the cover off the tin canister. THE MAGIC LANTEKN. 39 * It is, moreover, important that they should be turned “true i.e., that the hole should be perfectly central, so that when turned on its axis the distance from the jet may be uniform. On account of the tendency of lime to absorb moisture and “slake, 5 ' magnesia compressed into hard cylinders, and even zirconia, have been recommended, the latter on account of its property of being at once the most infusible, unalterable, and most luminous of all chemical sub- stances at present known when exposed to the action of an oxy hydrogen flame. Where it is impossible to purchase lime cylinders, as is sometimes the case “ up country 55 in India and Australia, cylinders may be fashioned with tolerable accuracy by sawing quicklime into rectangular pieces 1^ inches long by f inch square, and filing down the corners. Chalk may be used in extremis ; but the light is much inferior, and the chalk soon crumbles away, the disengagement of carbonic acid assisting the disintegration. Where it is possible to procure ordinary coal gas, it will be found a convenient substitute for, and save the trouble of making, hydrogen. It should not, however, be used from “the main," as in the case of oxycalcium, the amount of force with which it impinges on the lime cylinder being insufficient ; but should be col- lected in a gas bag, and pressure applied in the usual way. It may be observed, in connection with the subject of pressure, that iron weights, although obviously preferable, are by no means indispensable ; the pressure boards usually supplied are furnished with a ledge or shelf, upon which a fender and fire “irons, 40 THE MAGIC LANTERN. or other heavy “ chattels ” may be placed, taking care* not to diminish pressure by the removal of any weights until the stopcocks are turned off. Bags filled with sand form convenient weights, and save the trouble of carrying iron weights from place to place. The intensity of the light is materially influenced by the pressure, which should be liberally applied ; and it is important not only to have equal weights, but bags of equal size, so that the pressure may be equally exerted over the same number of square inches. The successful working of the Oxyhydrogen Light is based upon well-established facts in chemical science con- nected with the “ combining volume ” of gases ; and whereas one volume of Oxygen requires for its com- bustion two volumes of Hydrogen, when Coal Gas or Carburetted Hydrogen (C 2 H) is substituted, nearly equal bulks of these gases should be used, the exact proportion varying with the purity of the gas, and ascertainable at the time of burning by the quality of the light. An extra bag of Oxygen should therefore be prepared when Coal Gas is intended to be employed. It should be understood that the gases used in the production of these powerful lights, especially Oxygen and Carburetted Hydrogen, have a deleterious influence on the india-rubber gas bags and tubing, and that any overplus at the conclusion of an entertainment should therefore be expelled, and the bags not filled too long before beginning to v work. The preceding woodcuts and their description will have shown the reader that a few yards of flexible india-rubber tubing, over and above that supplied with the apparatus at the time of purchase, will form THE MAGIC LANTERN. 41 f very desirable appendage to the outfit. The kind best suited for the purpose is that which is stoutest in the tube itself. That lined with a spiral coil of iron or brass wire is not so advantageous, since, if trodden on with sufficient force, the enclosed wire in bending often breaks the tube, and thus renders a great length useless ; and also, if the Oxygen gas contains traces of Chlorine, the wire becomes corroded, and forms a deliquescent mess in the inside of the tube. Circumstances sometimes arise in which it becomes necessary to place the lantern at a distance from the source of gas supply. In such cases, pieces of brass tubing, about two or three inches in length, called connectors, are used,* of such a diameter that some degree of force is necessary to strain the india-rubber tubing over the metal. Leakage will, however, some- times occur ; the tubing should therefore be firmly tied with packthread. Fig. 20. Fig. 21. Fig. 22. These simple connectors may be very advantageously replaced by a safety valve, f which will render the occurrence of an explosion quite impossible, even in the hands of the most careless operator. It consists of a metallic valve, made on the principle shown in the * See No. 12, fig. 35, page 76. t Brit, Journ. Photo. Almanack. 42 THE MAGIC LANTERN. diagram. Figs. 20 and 22 are intended to be attached!* to the lantern or burner, so as to be retained in the position they now occupy ; fig. 21 may be placed inside the india-rubber gas tube, or any other convenient place. It is kept closed by the spiral wire spring, the others by gravity. A light flap of unoxidizable metal (preferably aluminium) closes a hole large enough to allow the gas to pass, its elastic force raising the flap. Should a weight be accidentally removed from a gas bag, and a return current be thus produced, the valve would be immediately closed, the more securely the greater the force exerted ; and as it is the mixed gases only which explode, and the gases (by this arrange- ment) can only pass in one direction, perfect immunity from danger is thus insured. It should , however , never be forgotten that the cause of explosions is a return and mixture , and consequent ignition of the gases, and that absolute safety consists in keeping up a good pressure on both bags, and never diminishing that pressure while the gases are burning, or without first turning off the stopcocks. The success of the Oxyhydrogen Light is influenced by the use of much more pressure on the gas bags than in the case of the Oxycalcium arrangement ; it is therefore very important that all joints should be per- fectly airtight, a fact which is ascertained by holding a piece of incandescent charcoal or brown paper near the points of junction; if Oxygen be escaping, its pro- perty of supporting combustion will become at once ap- parent in the increased brilliancy of the charcoal, or the bursting of the paper into flame. If Hydrogen be escap- ing, a lighted match or paper will kindle it into flame. THE MAGIC LANTERN. 43 ■When all joints have been secured, the Hydrogen should first be lighted, and the lime cylinder turned round in the flame in order to warm it, dissipate moisture, and prevent its cracking. The Oxygen should then be turned on slowly until the required brilliancy of light is obtained — the degree of brilliancy being, in fact, the guide as to the extent which each stopcock should be turned on. An excess of Hydrogen imparts a reddish tint. In the absence of Clockwork (a desirable purchase where lengthy exhibitions are intended), and for the larger lanterns, the lime cylinder should be kept frequently turned, in order to avoid the diffusion ox minute particles of lime mechanically thrown off, which fall on the condensers, and also the reflection of the great heat by the concavity in the lime cylinder, which not unfrequently cracks the lens. In addition to this, small pieces of red-hot lime sometimes fall from the cylinder through the lantern, and burn the box on which it is supported, whence it becomes desirable to place a sheet of tin under the lantern to catch these pieces, and prevent the burning of the box. The metallic pin upon which the lime cylinder is supported may be brought near enough to the jet to allow only room for the cylinder to revolve freely. The two adjustments with which it is furnished are for the purpose of determining its distance from the jet, and allowing the cylinder to revolve on its axis; an arrangement the necessity for which becomes apparent very shortly after beginning to work, owing to the mechanical action of the jet of gas, aided by the intense heat, wearing away small cavities in the lime cylinder. 44 THE MAGIC LANTERN. This result may be avoided by the use of clo^[ work, which for this purpose can be obtained in a very compact form, measuring only 6| by 3£ by 2£. The fusee or conical wheel, such as is contained in all English watches, should be preferably furnished with link chain, as there is a tendency in catgut to snap when the apparatus becomes hot from continued use. Attached to the cylinder is a left-handed spiral screw, which ascends about one inch (the length of the lime cylinder) in the space of forty to sixty minutes, thus giving a vertical as well as a horizontal motion. A fan, supported on a spring to ease the friction, and of such dimensions as to cause the lime cylinder to revolve almost imperceptibly, is adapted to the machinery, thus avoiding too sudden changes. The object of these delicate adjustments is to produce the greatest amount of light ; and by way of further precaution, it may be observed that, an excess of Oxygen having a cooling effect, loss of light ensues : a slight excess of Hydrogen, however, burning with a faint lambent flame round the white-hot portion of the cylinder, produces the best effect. When Coal Gas is used, a deposition of Carbon on the Lime Cylinder often occurs. This may be pre- vented by adding to the Coal Gas one-sixth of its bulk of pure Hydrogen, and occasionally turning the cylinder. The brilliancy of the light is also said to be increased by this addition of Hydrogen to the Car- buretted Hydrogen. Kecapitulation. Carefully dust and wipe every portion of lanterns. Warm condensers, wipe and replace them. THE MAGIC LANTERN, 45 J^ili gas bags, according to directions, ^iace equal weights on each bag, if of equal size. Carefully dust and arrange slides before exhibiting. Water sometimes enters gas bag while filling. To prevent this, keep bag higher than purifier. All air should be expelled from gas bags. To prevent leakage, see that all joints are tight. To insure passage of gas, blow through tubes and jets. Use pure Chlor. Potash and Manganese for Oxygen. Use good Zinc and Sulphuric Acid for Hydrogen. Wash out and dry the Oxygen retort after use. If lime cylinder breaks, turn off the Oxygen. In commencing exhibition light Hydrogen first. Keep lime cylinders carefully corked from air. If gas bags are stiff, soften in warm room. Gas Bags. Jeanet and twill, rendered impervious to air and gases by treatment with india- rubber, are the two materials employed in the manufac- ture of gas bags. The former will answer very well for the Oxycalcium, while the latter, as being stronger, is more suitable for the Oxy- hydrogen Light. On account Eig. 23. of the wedge-shape imparted to them to facilitate the extrusion of the gas and their bulging when filled, an accurate statement of cubic contents cannot be given. A bag, however, having the dimensions 20 in. long by 46 THE MAGIC LANTERN. 14 J wide by 12-in. wedge, if it retained a pure wedje shape, would hold as near as possible one cubic fool^M gas, and upon the same assumption, the following table may be accepted as an accurate statement of the contents of gas bags of the dimensions given. Measurement. About cubic feet. 24 X 18 X 16 27 X 24 X 16 30 X 25 X 1 8£ 34 X 28 X 22 36 X 32 X 24 2 3 4 6 8 Gasometers. For India and other hot climates, where the use of gas bags is inadmis- sible, round or square metallic gas- holders are used, made either of cop- per, zinc, or galvanized iron. In construction and mode of action they closely resemble an ordinary gaso- meter, as will be seen on reference to fig. 24, which requires no explanation. The necessary pressure is produced by unhanging the weights and placing them on the top of the gasometer, and sometimes by the addition of 56 lbs. to these. Compressed Gases. Numerous efforts, attended with varying success, have been made to get rid of the impediments of gas bags, pressure boards, and weights, by the use of com- pressed gases, especially in America. Fig. 25 illus- THE MAGIC LANTERN, 47 jjptes the method adopted in this country. A is the wrought-iron vessel, B a well-fitted stopcock, C the regulating orifice, an enlarged view of which is shown at fig. 26, where it will be seen that a central diaphragm extends across the tube, and that a hole in its centre is plugged by a pin P, one end of which presses against a lever 0, which in its turn rests against a screw, furnished with a strong milled head : an inward Fig. 25. Fig. 26. turn of the screw forces the pin into the central hole and prevents the escape of gas, while a gradual turn- ing outward allows the gas to come forth with that easy and continuous flow so essential to the success of the lime light. The pin, and the aperture into which it fits, should be made of gold, or some metal not readily oxidizable. The connection with the lantern is made in the usual way at D. The Opaque Lantern. The Catadioptrical Phantasmagoria, introduced by Sir David Brewster, forms the basis of an ingenious modification introduced and registered in 1864 by an enterprising provincial Optician. It is represented at fig. 27, and in many respects re- 48 THE MAGIC LANTERN, sembles the Physioscope and the Opaque Microscope^ The main difference between this and the ordinary lantern consists in its representing by reflection, instead of transparency, an almost unlimited variety of opaque objects, such as card photographs, either plain or coloured, engravings, lithographs, coins, medals, plaster of Paris casts, bas-reliefs, &c., the latter producing a singularly raised effect. Fig. 27. Its successful use requires a light of intense bril- liancy ; nothing less than the oxyhydrogen light will do. The rays from such a source are collected by a concave silvered reflector, of large diameter (12 in.), and thrown upon the surface of a plano-convex con- denser, in order to concentrate the light upon the opaque object, which, thus brilliantly illuminated, THE MAGIC LANTERN. 49 transmits the rays through a double achromatic object- glass of large diameter and long focus to project the image upon the screen. When the works or face of a watch, with the “ second ” hand in motion, is thus exhibited, the effect is very striking, and never fails to elicit the warmest expressions of interest. The angular portion of the lantern is placed at 45° to the axis of the condenser, because of the necessity for the object-glass being out of the angle of reflection; and although especially designed for opaque objects, it can be replaced by the ordinary lantern front, and thus rendered suitable for the exhibition of transparent slides. It may be also made for dissolving effects, in the form of a double lantern, one over the other, or witli the angular compartment at each end of the square box. The reader will have rightly inferred from the description that this apparatus is of a somewhat costly character. A much less expensive one has, however, recently been introduced under the title of the “Wonder Camera,” which will enlarge a vignette album portrait to life size, very fairly, on a disc of 3 feet in diameter. The Aphengescope. “I do here bestow a simple instrument.” — ShaJcspere. This is another modification of the Opaque Lantern, and was introduced in 1866 for the purpose of ex- hibiting Cartes de Yisite and other opaque pictures on the screen by means of a pair of ordinary gas lanterns. When using the Aphengescope, the Lanterns L L, with their jets arranged in the usual way, are placed with their . backs to the screen, and their axes inclined at D 50 THE MAGIC LANTERN. right angles to each other, as shown in the diagram. This is effected by removing the brass focusing tubes and collars from each lantern, and unscrewing the Achromatic Lens A from the hexagonal box called the Aphengescope B. The lanterns L L being then placed sufficiently near to each other for their nozzles to enter Tig. 28. Fig. 29. the apertures provided for them, the instrument is secured in its place by lifting the lid and applying the adapting screws supplied for that purpose ; the achro- matic front is then replaced, and two grooved doors, D D, hold the pictures during exhibition, the operations of focusing, adjusting lamps, &c., being effected in the usual manner. There is a modification M of the instrument for use with one oil lantern, but the disc is necessarily smaller and less brilliant than with two gas lanterns. The double achromatic lens furnished with the earlier instruments has now been advantageously replaced by a single achromatic of larger diameter, resulting in a greatly increased brilliancy of image. THE MAGIC LANTERN, 51 The Slides or Pictures. , “ Why, all these should be in the lantern.” — Shakspere. A Magic Lantern without a collection of slides may not inappropriately be compared to a Theatre without scenery or actors, and the purchaser will consequently need some information relative to these important adjuncts. They may be considered under two different heads, viz., Paintings and Photographs. The Paintings are made on glass with transparent varnish, and are for the larger lanterns, painted on circles varying from 2 inches to inches in dia- meter. For the smaller lanterns, the paintings are exclusively executed on slips of glass, about 6 or 8 inches long by 2 inches wide ; * while the medium sized lanterns, although adapted for use with single pictures, may also be furnished with slides up to the length of 14 inches. It will be understood that the dimensions here given are merely approximate, and although applicable to the stock obtainable in most Opticians’ shops, may now and then be found not to agree with the sizes kept in some houses. The long, narrow slides consist of detached figures of clown, pantaloon, and other grotesque subjects, and sometimes of connected stories — e.g ., “ Death and Burial of Cock Bobin,” which seems to be always full of in- terest for the ever-rising generation. Such a slide is called — * See figs. 30, 31, 32, page 52. 52 THE MAGIC LANTERN. The “ Natural History Slide” abounds in good representatives of the division Verte- brata, viz., Mammals, Birds, Beptiles, and Fishes. Fig. 32. The “ Astronomical Slide” bears some really good diagrams of the Solar System, Earth’s Motion round the Sun, Spring and Neap Tides, Moon’s Phases, Rotundity of the Earth, &c., &c. These are very instructive and entertaining sets ; and it is to be regretted that equally favourable remarks cannot be made in reference to the remaining class, called “ Scrip- ture History.” The last-mentioned are slides in which subjects of the most sacred character are treated in a THE MAGIC LANTERN. 53 Fig. 33. Elephant Hunt, described by Du Chaillu. manner more calculated to excite ridicule than reverence, and comparable only to the vulgar and inartistic outlines which were once so common on Dutch tiles. It will be readily understood that the style of drawing and colouring which might not be inappropriate for such subjects as clown and pantaloon would be altogether unsuitable for illustrating the events narrated in sacred history. Such a treatment of sacred subjects cannot be recommended; and the purchaser of slides of this class is referred to the very excellent photographic reproductions of the old masters now to be found in every Optician's warehouse. .54 THE MAGIC LANTERN. The preceding remarks refer especially to those narrow slides varying in length from 6 to 14 inches, and employed generally with the simple Magic Lantern. It remains now to offer some remarks on the better dass of pictures, painted on separate circles of 2 inches to 4 inches diameter. Important improvements have lately been made by enlisting the services of the lithographer in their pro- duction. Outlines of great delicacy and beauty are prepared on suitable paper, and these being transferred to glass discs, are coloured by competent artists, thus insuring greater accuracy than was formerly possessed by the cheaper kinds of slides. The separate coloured slides include nursery tales, such as “ Blue Beard/' “ Cinderella/' “ House that Jack Built," tf Bobinson Crusoe," “ Pussy’s Hoad to Buin/’ &c., &C;, in sets of 6 or 9 slides, varying in price from £1 to £3 or £4, according to the quality of painting and the number of pictures. Panoramas are also included in this series, and views of remarkable buildings and places, e.g. f Switzerland, Holy Land, &c. ; illustrations of the travels of Gordon Cumming, Livingstone, Du Chaillu, &c. A scene from the experience of the last is appended, fig. 33. Sets of views, with effects for dissolving, afford scope for the display of great inge- nuity, and are a source of unfailing amusement and instruction. The Society for Promoting Christian Knowledge publishes a work on Natural Phenomena, by Charles Tomlinson, Esq., containing numerous illustrations, which, reproduced as paintings on glass for the Magic Lantern, form, with the book, the materials for an THE MAGIC LANTERN. 55 admirable lecture to a Sunday school. There is little difficulty in obtaining them from any respectable Optician, and this series (about thirty in number) can be recommended as proving entertaining and in- structive. Phantasmagoria pictures are essentially dis- tinguished from ordinary Magic Lantern slides by having the outline of the figure so filled in with black paint that light comes only through the figure (see fig. 9), while the ordinary slide (fig. 33) yields a com- plete circle of light. Slides of the Phantasmagoria character prove very attractive in an entertainment, owing to their bril- liancy as contrasted with the surrounding darkness ; hence statuary should always form a fair proportion of the slides for an exhibition, and it enhances the sense of brilliancy if the audience be allowed to sit in darkness for a few minutes before showing the first picture. If two Lanterns be used, and the statue placed in one and a piece of ruby or sapphire-tinted glass in the other ; by working the Dissolving Appa- ratus the statue appears to advance out of a blue or red cloud. Slipping Slide. Of all the slides, however, prepared for the Lantern, those with mechanical effects prove the most interest- ing to persons of all ages, from seven to seventy years ; they consist of slides provided with slipping plates, pulleys, levers, rack work, and other arrange- ments, by means of which life and motion are appa- rently imparted to the objects exhibited, and the phe- nomena of moving waters, storms, lightning, volcanic 5G THE MAGIC LANTERN. action, &c., illustrated, in the manner described by the showman as being “ as natural as though in reality. 1 ' The drawings on this page will give an idea of a M Fig. 35. simple slipping slide, wherein the picture is painted on two pieces of glass, one of which is firmly fixed in the frame, and the other moveable. These glasses are so adjusted that when the sliding glass is pulled out, an effect is produced which differs en- tirely from that shown when the same glass is pushed in. Lever Slide. An illustration is appended of another popular but rather more expensive kind of mechanical effect, pro- duced by what is called a Lever Slide, in one of THE MAGIC LANTERN. 57 which a horse, having approached the water, fig. 36, may be “ made to drink ” (the old adage to the con- trary notwithstanding) by raising the brass lever on the right hand, as shown in fig. 37. Fig. 37. More startling effects and greater excitement may be produced by combining the lever and slipping motions, thus producing a most vividly lifelike effect. When a pair of lanterns are used, as in the case of dissolving views, and sets of slides suitably painted are employed, the most pleasing effects may be produced, illustrating daylight views changing to moonlight; summer to winter, with falling snow ; fair weather at sea, changing to a storm with lightning and rain, 58 THE MAGIC LANTERN. returning again to a calm. Such slides are supplied in sets, varying in number from 2 to 12, and in various qualities, with prices corresponding to the amount of time and skill expended on the minute details. There is a very pretty imitation of a curtain supplied by some Opticians, furnished with an arrangement for “ drawing up/’ which forms a most appropriate begin- ning to an exhibition. There are two classes of Photographs for the Lantern, viz., instantaneous and other views direct from nature, and reproductions of ancient and modern engravings or paintings. It would be difficult to overrate the advantages which have accrued from the application of Photo- graphy to Magic Lantern illustrations, or describe the difference between the delicate and accurate little gems produced by its means, and the daubs which once were supplied for the cheaper lanterns. Some idea of the value of Photography, associated with the Magic Lantern as an educational instrument, may be gathered from the fact, that as the camera has now penetrated to almost every habitable part of the globe, the physical peculiarities of every country, to- gether with lifelike portraits of their inhabitants, and the form and arrangement of their dwellings, may be obtained in miniature, and reproduced as large as life. Photographs of the sun and moon in various phases, and partially and totally eclipsed, also the fixed stars and nebulse, have been obtained, and employed for lecture illustration. Enlarged photographs of micro- scopic objects have also been obtained, and these again still further enlarged to 8 or 10 feet in diameter, THE MAGIC LANTERN. 59 so that, in fact, a diatom no larger than a grain of sand may be shown of such a size in the lecture theatre that a large audience may together examine its details with perfect comfort. The productions of the most celebrated painters and sculptors may be shown with equal facility, as well as maps, hymns, music, &c., so that an entire school may learn or sing together. Amateur Photographers who have acquired the necessary delicacy of manipulation, may desire to prepare their own transparencies. This can be readily accomplished by placing the Camera with the arranged negative, near an open Fig. 38. window, in such a manner that the light may fall on a piece of white cardboard placed at an angle of 45° as shown in the diagram, fig. 38, which may be thus explained. A, fine white cardboard inclined at an angle of 45° to the negative ; B, negative and carrying frame with lateral and perpendicular movements ; C, Camera ; D, brown cardboard to prevent direct rays of light entering the lens from the window ; E, the table. The Chromatrope. “ Into all the colours of the rainbow.” — Shakspere. Fig. 39 represents the pulley form of the Chroma- trope (literally, colour-turner ), but can give no idea 60 THE MAGIC LANTERN. of the dazzling brilliancy of the effects it produces on the screen. There is nothing it. resembles so much as the kaleidoscope, with the addition of constant motion and rapid change. It was first shown at the Poly- technic Institution about twenty-five years ago, and consists of two discs of glass painted with an almost endless variety of geometrical and other designs in brilliant colours. By turning the handle shown in the figure, the multiplying band causes the rapid revolution of one disc over the other, producing two apparent motions; and with good designs the result “ beggars all MrtLDt TV Fig. 39. description.” There are two forms, one of which is illustrated by fig. 39, the construction of the other being shown in fig. 40, the motion being accomplished by means of a double rack and pinion instead of a band. As there are two discs, revolving one over the other, each is necessarily furnished with a toothed rack, as shown in fig. 40, and the one pinion works both racks. It has been said that Chromatrope designs do not admit of description, but for the guidance of purchasers it may be stated that many are furnished with central paintings representing fountains, windmills, watermills, &c., in action, and] the words “Welcome,” “Adieu/’ THE MAGIC LANTERN. 61 “Good night/' &c., to be used at the beginning and end of an entertainment. The sentiment of loyalty is also provided for, sucl^ phrases as “ God Save the Queen/’ “ Buie Britannia/’ &c., forming the centre in some chromatropes, from which are thrown off the most dazzling rays of glory. The Eidotrope. This valuable accessory to the Magic Lantern was devised by Sir Charles Wheatstone in 1866, and consists of two perforated metal discs, which, by an arrangement precisely similar to the chromatrope, are made to revolve one over the other. The effects are so beautiful as to excite surprise that they should be obtained by a mechanical contrivance of such extreme simplicity. By slow revolution, hexagonal, octagonal, and other geometrical figures are obtained, with delicate gradations of shadow ; while a more accelerated motion produces the * effect of stellate flashings or scintillations of light. Colour may be imparted by the use of very delicate tints of coloured glass. The Astrometeoroscope is a recent invention, not altogether dissimilar from the Eidotrope, though more costly in construction. It produces effects like falling stars and shooting comets. Chinese Fireworks. These are similar in principle to the Colour-Top and Trocheidoscope, being founded on the phenomena of the “ persistence of vision.” They consist of a Chromatrope painted with bands of the seven pris- matic colours, and a set of shifting screens repre- 62 THE MAGIC LANTERN, senting temples, fountains, cascades, fireworks, &c., the outlines of which being traced on black painted glass, and inserted with the Chromatrope into the Lantern, become fringed with prismatic colours. Revolving Figures. In this class of slides the rack and pinion, so useful in the Chromatrope, is applied for the production of motion in the sails of a windmill, the wheel of a water- mill, or the paddle-wheel of a steamer ; the mill itself, and the landscape surrounding it, being painted on a fixed disc of glass, while the sails are painted on a disc having a toothed rack attached to its circumference, to which motion is imparted by the pinion handle, fig. 40. Such slides form an interesting and valuable addition to the outfit attached to the larger sizes of lanterns. Moving Waters. Under this title two forms of slides are sold ; by means of which, in a single or double lantern, very pleasing effects may be produced. In the simplest form, a moonlight scene is painted on a fixed disc, and THE MAGIC LANTERN 63 the “ rippling waters 55 on a piece of glass attached by one corner only to the framework of the slide, which, being moved np and down, causes the appearance of a ripple on the water. Another somewhat more expensive, but infinitely more truthful effect is produced by a slide having two moveable and one fixed disc of glass, and known as the “ Moving Water with eccentric motion / 5 In this slide, not only is the ripple produced, but the heaving of a boat upon the waves, the “ rolling 55 of the sea, and the “hovering 55 motion of birds is imitated with surprising closeness to nature. General Precautions for Use of Slides. It will be well, as soon as possible after purchasing a set of slides, to have a private performance, for the purpose of ascertaining eocactly how far in to push each slide, how high up or low down in the slide holder each should be placed, &c. In the case of chroma- tropes, and other slides bearing printed words, as “ welcome , 55 “ adieu , 55 in a wreath of flowers, it is im- portant not only to insert the slide upside down , but with the right side towards the front, for unless this precaution be observed the most ludicrous results are produced. This preliminary examination of the slides is espe- cially necessary in the case of dissolving views, where it is required that the “ moonlight 55 in one slide should “ register 55 with the space in the sky of the other in which it is intended the moonlight effect should be brought on. This “ correct registration 55 can only be obtained by a preliminary experimental trial of each THE MAGIC 1 LANTERN. 64 set of slides, and by making notches or attaching such other distinguishing marks as can be readily under- stood in an obscure light, or felt in the dark , and enable the operator so to place the slide in the lantern front that the correct effect shall occur with ease and precision on the screen. The words right, left, top, front, will suggest themselves as being suitable for printing, in large type, on slides of the kind now under consideration. It should always be remembered that the exhibition of pictures by the Magic Lantern has to be conducted, if not in total darkness, at least in so obscure a light that the operator has to depend more on the sense of feeling than sight ; it is therefore of the first import- ance that the number of slides to be shown should be determined beforehand, that these should be carefully freed from dust and linger marks, and arranged in the order in which they will have to be exhibited ; also, that they should be so labelled as to be readily distin- guishable one from another in the subdued light re- ferred to, for which purpose white paper labels, x If in, bearing figures one inch long, should be attached to the “ right ” side of the picture, the frame of which should bear a notch on that side turned to- wards the source of light and heat , which should be the side upon which the picture is painted, and not the bare glass, when showing on an opaque screen, but when showing through a transparent screen the paint- ing should be turned away from the light. The clear- ness with which the slides are shown is greatly de- pendent on the maintenance of perfect darkness, on which account it is desirable to slide the hand gra- THE MAGIC LANTERN. 65 dually over the front of the lantern during the in- terval of exchanging one slide for another, so that the dazzling disc of light may not unfit the eye for the appreciation of the next picture. There are slide- frames so constructed that square glass slides may he pushed through in succession, and the interval of bright light thus avoided, while some lanterns are fur- nished with brass caps wherewith to cover the fronts while changing slides. It should also be recollected that the intense light necessary for the effective exhibition of Magic Lantern Slides is accompanied by great heat ; and as the oil and water colours and varnish of which the pictures are composed are unfavourably affected by heat, it is desirable that they should not be too long submitted to its action ; five minutes generally suffice, but the time should never exceed ten minutes. The 'Screen. “There’s magic in the web of it.” — Shalcspere. The qualities necessary in a good screen are — 1. Freedom from seams, folds, ^ or creases. 2. Pure white- ness. 3. Freedom from texture. 4. Adequate size. 5. Opacity, or transparency. The materials employed, with the view of attain- ing these conditions, are linen, calico, muslin, and a material called “ union but of these four, linen is decidedly to be preferred, as including more of the above qualities than either of the others. Linen can be obtained of the width of 10 feet with- out seam ; it is stronger than calico ; and although this latter material is cheaper in the first outlay, it will not E 66 THE MAGIC LANTERN. bear washing like linen, which is, moreover, quite as transparent, if not more so than calico, when moistened for showing pictures through the screen. If a larger screen than 10 feet square be desired — say, for instance, 20 feet square, — it should not be made by joining two 10-feet widths of linen, for that would give a seam in the centre, but one 10-feet width should have a 5-feet width sewed on to each side, so that the centre of the picture may be free. If extreme transparency be desired for exhibiting microscopic objects on a comparatively contracted field of three or four feet in diameter, a material known to drapers as Nain Zook Muslin may be advantageously employed, moistened or varnished, and stretched over a child's hoop of the required size. This form of screen, though very elegant and efficient, is seldom used, on account of its expensive character and want of portability. The framework necessary for stretching the screen may be extemporized on the occasion by using two clothes-props, or other material of sufficient length and weight to stretch the fabric ; but the bulky cha- racter of the frames and rollers supplied at the shops renders them undesirable purchases. Where a screen with a seam must necessarily be employed, it should be so arranged that the seam is in the lower part, so as to come among the dark objects which usually occupy the foreground of a picture, and thus leave the brighter middle distance and sky free from the dark line which would be unavoidable were this precaution neglected. The material of which the screen is made should be THE MAGIC LANTERN. 67 kept clean and free from folds, for which purpose it should be rolled on a pole about three inches in diameter, and of suitable length. When so far soiled as to require washing, it should be carefully ironed before using, or if this be regarded as too troublesome an operation, stout white paper may be smoothly pasted over the whole surface, and then whitewashed ; should this require renewing, a fresh coat of white- wash may be very readily applied, and a pure white reflecting surface thus obtained. Where it is convenient to assign a permanent place to a Magic Lantern Screen, as at the end of a school- room, it may be mounted in a manner exactly similar to the ordinary linen blinds in a bedroom window, and coated with pure dead white “ distemper/' which yields the purest white known for this purpose. To neutralize the yellow light of an oil lamp, a faint tinge of blue , called “ French white/' may be laid on. Beautiful effects may also be produced with statuary, and similar subjects, by using as a screen a piece of finely ground focusing glass, about two feet square, which, being suitably framed, may be placed on the table to receive the image. The Lantern Microscope. “Never ceaseth to enlarge.” “The bigger bulk it shows.” — ShaJcspere. This instrument is intended to show natural objects, suitably prepared and mounted with Canada Balsam, between two discs of glass. They consist of details in the anatomy of a bee, wasp, flea, spider, larvse of insects found in stagnant water, as gnats, dragon-flios 68 THE MAGIC LANTERN. parasitic and other insects, parts of insects, sections ot woods, teeth, bones, fossil bones, shells, lace, silk, mnslin, &c., &c. ; and as such objects are smaller than paintings for the Lantern, and contain more delicate Fig. 41. details, a proportionately higher magnifying power is required, which may be adapted to the front of the larger sizes of lanterns- at a moderate cost. By filling a glass trough (T) with diluted sulphuric acid, and dropping into it a few pieces of granu- lated zinc, the decomposition of water may be shown to an entire audience. Aided by a 6-cell Smee’s or Groves Battery, and a cell like T, fig- 42, the power which Palladium possesses of absorbing 900 times its volume of hydrogen may be also shown ; the snake- like contortions of the strip of metal, and the bubbles of gas escaping on the reversing of the current, proving very interesting. The crystallization of salts may also be shown by placing a drop of a strong solution of Epsom salts, or sulphate of copper (blue vitriol), on a piece of glass of suitable size. Another effective result is obtained by placing in THE MAGIC LANTERN. 69 the glass trough a small horseshoe magnet, and drop- ping around it some iron filings, which will be found to arrange themselves, or rather be attracted by the magnet, in a most extraordinary manner. Fig. 42. The above diagram shows this important addition to the lantern in sec- tion. L is the source of light, which should be preferably either oxy- hydrogen or oxycalcium; but excellent results have been obtained by the writer with an ordinary Argand oil-lamp, on a disc one foot in diameter, which is quite large enough for most objects. At C are shown the combination of condensing lenses, and at D the opening through which the ordinary slides are introduced. At E the usual object-glass has been unscrewed, and replaced by the Microscope, which has an opening at 0, into which the objects are thrust, and retained in position by a strong spiral spring, which may be held back while placing an object, by the milled heads F. Two powers are usually supplied with the instrument, the lowest of which is shown in position at G, the higher power H being detached. T is a glass trough, the use of which is explained below ; it is made of a size suitable for entering the aperture at 0. Exhibitions of microscopic objects by the aid of the Magic Lantern in the drawing-room sometimes fail to give that complete satisfaction which is desirable, 70 THE MAGIC LANTERN. owing to attempts being made to show them on too large a scale in proportion to the light employed. The writer has given very satisfactory exhibitions on a sheet of Imperial (22 x 30), or Atlas (26 x 31), white cardboard, fastened by drawing pins to a board, and fixed against some books or on a chair. In this way the proboscis of a blow-fly may be enlarged to 2 feet in length, and this is found to be quite large enough for most private assemblies. Of the two “powers," G and H, the lower one serves to exhibit objects of an inch or more in diameter, such as fronds of maiden-hair fern, seaweed, whole insects, mosses, wings of moths, butterflies, &c. ; while the higher power (the smallest in appearance) is best adapted for showing the more minute objects, such as animalcula, hairs of animals, spicules of sponge, and scales from the wings of butterflies, moths, &c. Large, collections o± such objects may be selected from the stock of the Optician supplying the Microscope. A third object-glass of great power, and having a rack and pinion adjustment, is sometimes furnished for the most minute objects. It is desirable to have two or three sets of lenses, of different powers, with the microscope, which are varied to suit the object to be exhibited; and it is important to observe that when minute objects are being exhi- bited, and a high power consequently in use, the source of light should be drawn farther from the condensing lenses. A very interesting addition to the microscope consists of a diagonal mirror, whereby the image of the objects, instead of being projected directly on an opaque screen, may be thrown down at right angles on THE MAGIC LANTERN. 71 a sheet of paper placed on a table, and a drawing very conveniently made. The Magic Lantern Kaleidoscope. “Beggars all description.” — Sha/cspere. Fig. 43. The Kaleidoscope * was invented by Sir David Brewster in 1814, and all who have witnessed the beautiful effects produced by the instrument will welcome its adaptation to the Magic Lantern, which, notwithstanding the attendant optical difficulties, has at length been accomplished. The instrument is shown in section at fig. 44 ; A being a sectional view, showing the disposition of the mirrors ; B an outline of the eight-celled image ; C a side view of the brass mount, containing the reflectors and lenses, with sliding adjustment for focusing, and projecting the image upon the screen. Fig. 43 shows how it is attached to the lantern, viz., by unscrewing the front, and screwing the Kaleidoscope into its place, turning it round in its sliding tube until * KaXoc, beautiful ; tidog, form ; aico7reio, to see. 72 THE MAGIC LANTERN. the reflectors are upright like the letter V. A rack slide, containing some fragments of coloured glass, bugles, beads, and other transparent objects, is also shown ; this is introduced into the usual slide-holder of the lantern, as shown in the cut, and the focus ad- justed by sliding the Kaleidoscope in or out until its back lens is at a proper distance from the slide. Fig. 44. In a former paragraph, the great importance ol having the various parts of the lantern and the objects to be shown properly centred has been dwelt upon at some length. Now, however, attention has to be directed to the importance of having a portion of the present arrangement out of centre. That portion is the light , which should always be above the centre of the condensers ; in the case of oil lamps, the elevation should be about half an inch, but with the oxy calcium, one inch, as shown in fig. 43. The maximum of illumi- nating power is obtained in the usual way, by pushing the light backwards and forwards, and the correct focus is obtained by means of the front sliding tube. Any dark portions of the image may be removed by turning the Kaleidoscope round a very little to the right or left. The “un-centring” of the light may be accom- THE MAGIC LANTERN. 73 plished, in the case of oxycalcium or oxyhydrogen lamps, by means of the rod at the back of the lantern ; while for oil lamps, two pieces of wood, half an inch thick, placed in the pan, will effect the purpose. The instrument, before using, should be warmed, to prevent what is popularly known as the “ steaming of the glass/’ Hackwork frames, containing pieces of coloured glass, are supplied by the Opticians ; but exceedingly beauti- ful effects are obtainable with the Chromatrope, a piece of perforated zinc, the bow and the wards of a key, grasses, feathers, a bunch of oats, &c., &c. The Oxyhydrogen Polariscope. ‘‘Full of forms, figures, shapes, objects.” — Shalcspere. Fig. 45. Fig. 45 illustrates the method of using the Polariscope when detached from the lantern, as a “ Table Polariscope,” for the examination of sec- tions of uni-axial and bi-axial crystals, unannealed glass, &c. 74 THE MAGIC LANTERN. Fig. 46. Fig. 46 shows the Qxyhydrogen Polariscope, which consists of two tubes inclined to each other at an angle of 56° 45', and truncated at their points of junction, the oval space thus formed being closed by some ten or twelve pieces of thin crown glass, the lowest of which is blackened to absorb the polarized ray. This apparatus replaces the object-glass of the lantern, which should have condensers not less than 3| inches diameter. When attached, it will be seen that the light emanating from the point L, after passing through the condensers C ', becomes incident on the crown glass G, inclined at the polarizing angle (56° 45') ; the reflected, and in this case polarized light then passes through the selenite, or other object in the aperture at 0 ; after which it is brought to a focus by the object- glasses at F, and finally again polarized, or analyzed , by the Nicol’s prism, P, and thence thrown on the screen, the disc on which should not exceed three feet in diameter. The phenomena connected with the polarization of light are attended by a most gorgeous display of colours, and are, in consequence, among the most attractive in the whole range of physical optics ; an apparatus, there- fore, which facilitates their exhibition to an audience becomes a most valuable adjunct to the Magic Lantern. The ^subject itself is, however, of too recondite a nature to admit of adequate treatment in the present THE MAGIC LANTERN. 75 manual ; the reader is therefore referred to Pereira's lectures on “ Polarized Light,” “ Ganot’s Physics,” and other works on Physical Optics. The objects best suited for the Polariscope are de- signed with lilms of selenite of various thicknesses and forms ; sections of quartz, cut in different relation to the axis of the crystal, producing most splendid tints ; unannealed glass, quill, Iceland spar, and, indeed, almost any matter the particles of which are in a state of tension. Specimens may be seen, and lists of the 76 THE MAGIC LANTERN. various designs are obtainable from Opticians supply- ing the apparatus. When it is desired to illustrate the various plieno- Fig. 48. Fig. 49. Enlarged View op Magnetic Regulator. mena of Physical Optics, as in a course of Lectures on Light, the best possible arrangement is that devised THE MAGIC LANTERN. 77 by MM. Duboscq, and shown in figs. 47 and 48.* For a detailed description, the reader is referred to the admirable work from which these illustrations are reproduced. It may be here briefly stated that A, B, D is a solar microscope fixed on the outside of a brass box, inside which are two charcoal points in connection with a powerful battery, so placed that the space between them coincides with the axis of the lenses of the microscope. Electricity, from the opposite poles of a battery, reaches the points by the wires H, K, thus producing the necessary brilliant light. The two carbons are found to consume at unequal rates, and as it is of the first importance that the points should be maintained at a uniform distance, the Regulator P is introduced. In this regulator (the details of which are shown in fig. 48) the two charcoals are moveable, but at unequal velocities, which are virtually proportional to their waste. The motion is transmitted by a drum placed on the axis, x, y, fig. 48. This turns two wheels, a and 6, the diameters of which are as 1 to 2, and which respectively transmit their motion to two rack- works, C' and C. C lowers the positive charcoal p, by means of a rod sliding in the tube H, while C' raises the negative charcoal n twice as rapidly. By means of the milled head y , the drum can be wound up, and at the same time the positive charcoal moved by the hand ; the milled head x moves the negative charcoal also by the hand, and independently of the first. The two charcoals being placed in contact, the current of a powerful battery of 40 to 50 elements reaches the * Ganot’s Physics, new edition, Longmans and Co. / 78 THE MAGIC LANTERN. apparatus by means of the wires E E'. A magnetic regulator, of which fig. 49 is an enlarged view, furnishes the means of maintaining a regular and continuous light, until the carbons are quite used. The microscope can be replaced by the object-glass of a Phantasmagoria Lantern, by variable diaphragms, lenses, prisms, &c., &c., to illustrate an endless variety of optical experi- ments. Dissolving Views. ‘‘Look here upon this picture, and on this.” — ShaJcspere. Fig. 50. — Dissolving Views. The simplicity of the means by which the numerous illusions and peculiarities already described are pro- duced will have shown the reader that the results are attributable, not so much to any changes effected by modern science in the chief instrument, as to various THE MAGIC LANTERN. 79 accessories recently discovered and applied by the aid of racks, slides, rollers, &c. The apparently supernatural scenes with which science has familiarized us need not again be referred to ; we will pass on to the chamber where the charm- ing and ever-changing Dissolving Views are being exhibited. Most persons would be disposed, if these exhibitions were not so familiar, to make a great effort to see them ; but familiarity has, perhaps, in this case, bred a sort of half-contempt, which the beauty of the dissolving charm seldom merits. The scenes presented by this arrangement are some- thing like the following : — -A noble palace, glowing in the golden beams of a setting sun, stands before us ; its walls glittering in their marble purity, filling the imagination like an architectural dream, and forming the centre of a lovely landscape, with a background of majestic mountains, at the foot of which a limpid stream runs at its own sweet will, the cerulean heavens shedding a charm over all that makes us think of “ a better land ; ” when lo ! a gradual indistinctness appears, the “ insubstantial pageant fades ; ” the glow is gone ; a grey vapour atmosphere succeeds ; the river is ice ; the trees are bare and leafless ; the meadows and gardens white and flowerless ; our spirits fall. But now the skaters appear on the scene ; the snow falls , too , at first slightly, then heavily, and the scene is half obscured, when once more appears the enchanted palace, the everlasting hills, the beauteous landscape, and the blue sky ; and when this scene disappears, we go away filled with delight, and wondering how the charm was wrought. 80 THE MAGIC LANTERN. This interesting and valuable method of exhibiting Magic Lantern Slides, and producing with them what are called “ effects/' involves the employment of two or more lanterns, placed either side by side, or one over the other, and so arranged that their axes may be made to converge and produce coincident discs of light on the screen. The two lanterns are fastened to a base-board, or Fig. 51. the top of the box in which they are contained when not in use, as in fig. 50, and to the front of this box is attached a rack and pinion (worked by a winch- handle), to which are attached two toothed fans or combs. The length of the rackwork is so adjusted, that when turned completely to the right or left, one or other of the lanterns is completely closed, while the other is as completely open. Fig. 51 is another THE MAGIC LANTERN. 81 and very convenient form of Dissolving View Appa- ratus, turned round to show the position of the oxycalcium lamps, and an arrangement, liAtiyni /Ohs//, t^uirC &l '€c^t/^ / A j (s //(y6/vu,Cs ^h'truft'l ad ci^yi . / . / Oi ltAstvUV’i’ t tss^'l'i' 2s TH<--sy£ O^dc^ps* - 0-11 nl .£/yyuiJs Tie / Clever Stage Illusions Produced With Mirrors and Other Contrivances. PEPPER’S GHOST. One of the best of those Illusions which confound the senses in spite of the judg- ment, is the one known as “Peppers Ghost,” first produced at a cheap London theatre by Professor Figgetter, who was then but thirteen years old. Like most of the famous inventions it came about through observance of nature’s laws. Pro- fessor Figgetter observed his mother’s image reflected in a polished window glass, and following out tne principle there re- vealed set to work, and in a primitive form brought forth the ‘‘ghost show,” w 7 hich speedily became the talk of the town. This illusion is so simple that it requires but little explanation. The subject is reclining on a dark-covered background at an angle of forty-five degrees, and the strong light thrown causes her to be reflected on a polished glass above, tilted at the same angle. To heighten the effect figures are introduced by the management from the stage level behind the polished glass. The light below, when turned on or off, causes the reflected figure to appear or disappear in the midst of those actually moving about the stage. Follow-, ing the various kinds of ghost shows came Colonel btodar's living head of the “Sphnix.” His was the first illusion that dispensed with parts of the body and OPENED A NEW SYSTEM of illusions and necromancy, and then in rapid succession came the “ Mysterious Cabinet,” “Fatima,” “Komah,” and so on. It is a significant fact that- the famous sphinx was evolved from the kaleidoscope, a toy that almost every child has, at some time or other, had, and found delight in its ever-changing colors, diamonds, circles, prisms and squares. The sphinx speedily became famous for the cleverness by which the body was concealed and its oracular utterances and replies to questions. The body is hidden in the sphinx by two mirrors, joined icPthe centre with two bevelled edges leaning toward the floor at an angle and re- flecting the floor, painted or draped, in a manner exactly similar to the back-ground and sides, even a fourth table leg being sometimes reproduced. Colonel Stodar, who invented the sphinx, in his efforts to keep to himself all the profits of the “head without a body” patented it and thereby gave the secret of the con- struction away, and not busy showmen to work devising’ other illusions on the same order. Had he not dene so it is more than probable that the secret would have re- mained such until the present day. Among THE MOST POPULAR ILLUSIONS is “Tauma,” This is a pretty young woman who has apparently been cut in halves. The figure from the waist up is shown swinging on a dainty little trapeze. By grasping the ropes at either side the lady at times lifts her half body clear of the trapeze. The lecturer, to show that there are no con- cealed mirrors or supports, puts his arm or a cane under the trapeze and some distance back of the bright lights at the base of the stage. Thi9 illusion is not produced by mirrors. The whole woman is before your eyes, but on account of the brightness of the lights in front the darkness back of the curtains is intensified. The waist portion of the figure is a dummy, which is attached to the real girl under the perfectly fitted dress waist. The body of the girl, draped in sombre black, rests on an inclined board, also draped in black, running back into the curtained recess. It is impossible for the spectator to see the faintest outline of this black draped portion of the figure, no mat- ter how positive he may be that it is near him, and therefore ought to be discernible.