THE Franklin institute LIBRARY The Elihu Thomson Collection • Given by Mrs. Elihu Thomson CLASS BOOK ^^.^^j=L5" ACCESSION y<$' Pijsr^ REFERENCE No. 29. Carl Zeiss OPTISCHE WERKSTATTE Jena. MICROSCOPES AND MICROSCOPICAL ACCESSORIES. 1891. The followinji' Catalogues may also be had gratis on application Illustrated Catalogue of Photographic Objectives. Catalogue of Optical Measuring Instruments. LIBRARY f " THE " > FRANKLIN INSTITUTI THE GETTY CiNTER UBRARY Terms. Each article specified in this Catalogue may be supplied singly or in sets at the prices subjoined. The price of completely fitted Microscopes is in all cases the sum-total of the individual items. The quotations are understood: goods delivered at Jena, packing charged extra, net cash without any reduction, cheques upon a principal town in Germany, England or France being also accepted. Goods are forwarded, value insured, at the risk and cost of the buyer. In case of special shipping instructions not being given foreign orders will be despatched by the best possible route and with every precaution. It is requested that name and address be plainly written in all orders and, to prevent mistakeSf that the number or date of this Catalogue be quoted, Jena, 1891. Carl Zeiss, Optische Werkstatte. Telegrams: "Zeiss Werkstatte Jena". ^ A selection of completely fitted Microscopes for the most varied requirements will be found at the end of this list. ^ We shall be glad to supply for scientific publications electros of the figures contained in this catalogue. Some of these also in reduced sizes. Unauthorized reproductions of the figures or text of this catalogue are prohibited. Contents. page ObjectiYes and Eye-pieces l Apochromatic Objectives 7 Compensating Eye-pieces 15 Projection Eye-pieces 18 Achromatic Objectives 19 Huyghenian Eye-pieces 23 Accessory Apparatus for testing Objectives 24 Stands 26 Specification and Prices of the various Stands 32 Accessory Apparatus for the Microscope Illuminating Apparatus 57 Appliances for changing the Objectives on the Stand 67 Apparatus for measuring and counting microscopical Objects . . 70 Drawing Apparatus 77 Arrangements for Polarisation ... 79 Spectroscopic Eye-pieces 81 Various optical and mechanical Apparatus 85 Apparatus for Photo-micrography 92 Dissecting Microscopes and Magnifiers 100 Microtomes HO Slips and Covers 112 An asterisk denotes that the ' apparatus or optical combination so marked originated in our factories, i. e. was either introduced by us as new or, at any rate, first made by us in the manner here described. Objectives and Eye-pieees. In our previous catalogue (No. 28, issued in 1889) we referred to the advance made, through our efforts, a few years previous to the publication of that catalogue, in the practical development of the microscope. It was there pointed out that this advance was, in a great measure, due to the results obtained in the production of new glasses (borate and phosphate glasses in particula]') by the ''(llastechnisches Laboratorium Schott and (jenossen", which has been established here, with our cooperation, as the outcome of long continued ex- periments by Dr. Schott and Prof. Abbe. By the use of these new glasses, which by their properties with respect to refractive power' and dispersion con- stitute a much superior material for the construction of microscope lenses, and the application of new formulae in the construction of the lenses, we have, since 1 886, produced microscope objectives which possess a considerably m ore perfect correction both of chromatic and spherical aberration, and therefore a much greater concentration of light in the image, than had hitherto been attained. We also introduced eye-pieces specially adapted for use with these objectives, which, in addition to other advantages of minor importance, produce almost perfect achromatism and give a sharp image over the whole visual field. These new combinations which were first published in August 188() under the designations "Apochromatic Objectives'' and "Compensating Eye-pieces" and ■"Projection Eye -pieces" are now extensively used and appreciated (we refer to the numerous comments in various scientific and technical periodicals and works), and have stood the test to which they were put as a means of advanced scientific research. At the request of eminent microscopists the series of these objectives has been increased by the addition of a few new types (vid. l^elowj. (Bazl 2 The present catalogue includes, in addition to this new series, most of our older achromatic objectives and ordinary eye-pieces. For although there is every reason to assume that in the course of time the apochromatic lenses, at least in the more difficult departments of microscopical research, will entirely supplant the older objectives, yet there are a great many problems in microscopy that do not demand the highest attainable degree of perfection for their solution and in the plurality of such cases the former achromatic microscope will be all that is needful, provided it is good of its kind and judiciously and carefully made. The objectives and eye-pieces of the older type have certainly this advantage that, thanks to their much simpler construction, really good lenses of this class can be supplied at considerably lower prices than the lenses of the new series which are much more complicated and involve in their production an extraordinary degree of manual skill. For these considerations we have, in publishing the last edition of our cata- logue, omitted from the list of our foi-mer objectives only those numbers whose special purpose is at present undoubtedly better realised by the apochromatics — namely a few of the low power dry lenses of relatively large aperture and the very short and very long focus lenses in the series of water and homogeneous immersions. The original achromatic objectives, moreover, li a ^' e been considerably improved in detail by the use of the new varieties of glass and such other alterations as their type of construction permitted. The higher powers of these lenses — both of the dry and immersion series — where the advance thus effected is relatively considerable, might be termed, after the example of other makers, "s emi - ap o ch r o m at i c lenses". The original prices of these systems have not sustained any change l)y these improvements. In the special catalogue of 1880 we made a l)eginning and introduced a rational system of designation of the objectives and eye -pieces of the new series in contradistinction to the prevailing purposeless and arbitrary method. Although we consider this system to be more practical than any of the usual conventions of lettering and numbering, and though its universal adoption would constitute a decided step in advance, we consider it nevertheless wiser to desist, for the present, from redesignating our older (achromatic) objectives. 3 Grroat alterations in tlie focal lengths of both objectives and eye-pieces would have been necessary in order to designate these by the same convenient round numbers as in the new series. Our microscopes, however, being in such extensive use, so many microscopists have become accustomed to the focal lengths hitherto adopted and the usual denotation of the various combinations, that a radical alteration in this direction might give rise to considerable confusion. For these reasons the former designation of the objectives by letters and the arbitrary numeration of the eye-pieces has been retained in the older series. Tlie iiiaiuifactiire of all our objectives is based upon a method of coiuidete theoretical computation of all the constructive tyi)es ])revious to their actual manu- facture. By this process, which was introduced by Prof. Abbe in our works in 1 a n d C may be used on t h e 1 a r g e English stands with lO-incli tubes without ai)preciable loss. _ 5 All the others, particularly the ap ochrom atic series and also the homogeneous immersions, perform more or less defi- ciently on stands of English model, u n 1 e s s sp e c iall y a d j u ste d for these. In foreujn orders it should always he stated irhether the objectives are to be adjusted for the short (continental) or for the lomj (En(jlish) tube. Thickness of Cover. All objectives in lixed mounts are, unless otherwise ordered, corrected for a medium thickness of cover between 0.15 and 0.20 mm. In the higher series (from the apochromatic 8-mm and achro- matic D upwards) the thickness of cover corresponding to th e most perfect correction is indicated on the side of the mount by small figures (millimeter). It is, as a rule, sufficient for ordinary work with those objectives which we supply only in lixed mounts, to use covers of an estimated medium thickness. Homogeneous immersion ob- jectives are, within wide limits, inde- pendent of the thickness of cover. Correction Adjustment. The gra- duation and numbering on the correction collar, read off on the lixed index, indicates directly for each position of the collar the corresponding thickness of cover (in hundredths of a millimeter) which yields the best correction for that position. The correction for cover must be carefully ad- justed, particularly in the case of the apo- chromatics 4.0. rJ.O mm (dry) and 2.5 mm (water immersion) and the achromatic lenses F and J, failing which the ef- ficiency of the lenses wall be greatly diminished. The homogeneous immersion ob- jectives are only supplied in fixed m 0 u n t s beause, as already stated, their efficiency is within rather wide limits Figr. 1. The correction ring b serves to adjust the distance between the upper part d of tlie system and the lower part e which is attached to the mounting a. 6 in(lei)endent of thickness of cover-glasses and also because any alteration in the distance of their lenses interferes with the perfection of their correction. Con- siderable variations in thickness of cover are best compensated for by slightly lengthening the body-tube for thinner covers, ,, shortening ,, .. ., thicker ones. On page 21) it is shown in what manner the thickness of cover -glasses of a mounted specimen can be easily ascertained by means of our stands. The immersion liuid which we recommend for the homogeneous objectives is C e d a r - w 0 0 d oil (from Juniperus virginiana) which we have used from the first. We supply the same in a thickened condition, which not only does away with its inconvenient fluidity, but at the same time yields almost perfect identity of refractive index with that of the cover -glass. A bottle of this oil is supplied with each objective and may be procured from us at any future occasion (price M. 0.75 pr 1/2 oz bot). We expressly request, that no immersion fluids derived from other sources be used with our objectives, or at least none which have not been carefully tested as to their proper refractive power — as is done by us — because the use of unsuitable fluids implies considerable loss in the optical performance of the objective. As regards the relative merit of the homogeneous and noii- homogeneous (water etc.) immersion systems, the former claim superiority over the latter (focal length and aperture being equal) by reason of their eminently superior defining power and their greater insensibility as to variations of thickness of cover -glasses. Water immersion systems are only to be preferred in such cases where the nature of the objects does not admit of oil being used as immersion fluid. The mounts of all objectives are provided with the Eiiglisli standard thread of about 20 mm external diameter. In the series from A to J however, and also in DD when not fitted with correction adjustment, the lower part of the mount containing the lenses is made to unscrew from the adapter and may then be used with the narrow-gauge thread. The name of our firm is engraved on the mountings of all objectives, on the apochromatics also the aperture, focal length and tube length for which they are adjusted and on the ordinary glasses the letter by which they are designated. When ordering objectives which are intended for use with stands not made by us, it is in all cases, tvhere these are not noted for having the same screw-thread and internal diameter of tube, advisable to send the tube in question for the i^urpose of adapting the objectives and eye-jAeces. Apoehromatie Objectives. While referring to the paper of Prof. Abbe, entitled "Ueber Verbesserungen des Mikroskops mit Hilfe neuer Arten optischen Glases" (Sitzungsberichte der Med.-naturw. Gesellschaft zu Jena vom 9. Juli 1H8()) ^) and to the forthcoming work of our colleague Dr. Czapski on the "Theorie der optischen Instruniente" (Breslau 1893, Trewendt), which combine to furnish a complete exposition of the scientific aims and principles which governed the construction of the apoehromatie lenses, we must here content ourselves in briefly stating the essential features of these lenses. These objectives essentially differ from all other microscopical lenses hitherto constructed by the simultaneous realisation of the two following conditions: viz. 1) the union of three different colours of the spectrum in one point of the axis, that is to say, the removal of the so-called secondary spectrum inherent to the older achromatic lenses, and 2) the correction of spherical aberration for two different colours in contradistinction to that for one in the brightest part of the spectrum only. With all optical systems hitherto constructed, microscopes included, the sharpness of the image projected is limited to one particular colour of the light transmitted (i. e. green -yellow in the case of lenses used for ocular observations, blue-violet in photographic lenses), while the other rays give more or less confused images, appearing partly as colour fringes and partly as a general blur. With the apoehromatie lenses, however, the projected images are nearly equally sharp for all 1) Sent gratis on application. s colours of the spectrum, and the quality of the projected image is, therefore, within wide limits independent of the nature of the illuminating source, which may be white or compound, or monochromatic light emerging from any section of the spectrum. In the older series again complete colour correction is obtained for one zone of the objective only, a marked deterioration being observable towards the margin and the centre of the aperture, whilst in the apochromatic lenses it is corrected uniformly for all zones. Consequently, in using Abbe's test-plate, scarcely more colour is perceived with the most oblique illumination than with central light. Finall}^, even within the zone of the most complete colour correction of the ordinary achromatics, only two colours can be united in one point. The various coloured images therefore can only fall on the same spot in pairs between which there is a considerable difference in focus. In the new series, however, three colours are brought to a focus, whereby the amount of focal difference for the various sections of the spectrum, from the visible to far into the chemically active portion, is reduced to '/^ to i/^^, of its original magnitude i. e. practically eliminated, and this, as has been stated before, equally for each zone of the objective. The images due to each single colour, thus individually corrected, are rendered coincident und collectively form the final image i). The practical advantages of these new lenses become at once apparent. A considerably increased concentration of light with ordinary eye -piece observ- ation or any other mode of application under all possible conditions of illumination confers on these glasses an acknowledged superiority over the ordinary achromatic lenses botli witli respect to optical capacity and diversity of applicability. The natural colours of objects, even in the more delicate tints, are truly reproduced by these objectives. Close to the margin of the field, the images are nearly as sharp as in the centre, though tlie high aperture and the relatively great working distance render a moderate degree of curvature of the image unavoidable in these objectives as in the older ones; the central 1) It would be a grave error, both theoretically and practically, to view this process of achromatisation of a higher order as here defined in the light of a mere improvement of ordinary "achromatism", such as would result from a diminution of the secondary spectrum while yet only two colours are united, or from achromatisation embodying the principles here indicated but limited to one particular zone of the objective (which might be obtained by the introduction of suitable glasses into objectives constructed after the usual formula). The word "apochromatic" was introduced by Prof Abbe as a technical term for this other kind of achromatism, long familiar to scientists as a theoretical idea but only recently realised practically. With deference to intelligible technical phraseology it is desirable that this expression thus clearly defined by its author should retain its original meaning, and any attempt to utilise it for jiur poses of trade advertisements should be discountenanced. 9 and marginal portions of the field do, therefore, not appear in sharp focus simultaneously, but have to be focussed in succession. As a result of the great concentration of light afforded by these objectives, they permit of the use o f v e r y high power e y e - p i e c e s without detriment to accuracy or brightness of the image, thus giving high magnifying power with relatively long focal length, tlius yielding with the same objective a series of very varying amplifications. In the annexed list beside the apertures and foci the corresponding objective magnification is stated, i. e. the magnification which the ob- jective alone would give at the distance of distinct vision if used as a simple lens. This is simply 250 (distance for distinct vision) divided by the focal length of the objective in mm. For instance, the objective magnification of a 3-mm objective is: The apertures indicated are tlie guaranteed minimum values; the stated focal lengths are adhered to as closely as possible. Remarks on the use of tlie 2-mm Apocliromatic Lens of 1.40 mm aperture (homogeneous immersion). Owing both to the hyper-hemispherical form of the front lens, which is held in situ by a very narrow ridge at the extreme edge of the setting, and its rela- tively short working distance (0.2 mm) this lens demands careful treatment and should, in particular, be scrupulously guarded against shocks or pressure. As compared with the 2-mm lens of 1.30 aperture this lens possesses a greater resolving and defining power in the proportion of 14 : 13 and gives a brighter image in the proportion of 20 : 17. The 2-mm 1.40 is a decided advantage where exceptionally intricate problems requiring the most delicate apparatus have to be solved, and also in such cases where the lens is to serve as a means of controlling observations made with lower powers; for regular work preference should be given, generally speaking, to the 2-nim 1.30, owing, to the greater firmness of the frontal lens. The objective 3-mm 1.40 apert. has, however, this advantage over the 2-mm 1.40 that, while possessing the same optical capacity, it has a greater working distance and is also less delicate as regards its mechanical construction. 10 In reply to numerous enquiries and. in some cases, publicly expressed doubts respecting the durability of apochroinatic lenses we append the following statements. All glasses used in the construction of apochromatic lenses have been amply tested through several years' experience and offer a fair guarantee for their immutability, at any rate in temperate climates and on condition that the lenses are not subjected to any undue treatment. This statement does, however, not apply for the present to suit hot climates where an exceptionally damp and hot atmosphere constitutes an abnormally active decomposing agent, which even the older (silicate) glasses do not permanently resist; in these cases we disadvise the use of apochromatic lenses. A few isolated cases have indeed occurred even in our climate in which the one or the other of the constituent lenses of certain apochromatic systems have become turbid; but it would not be fair to hold us responsible for such contingencies. For be it remembered, the introduction of apochromatic lenses by us necessitated the application of entirely new materials which until then had not been used or tested. The first lenses, necessarily, lacked the kindly aid of experience and it is not surprising that a few failures should have occurred. Whereever varieties of glass used in the construction of lenses proved to be liable to deterioration, the lenses containing such glasses were subjected to reconstruction and all doubtful glasses supplanted by such that were known by experience to possess greater durability. Even as now constructed the apochromatic lenses are sensitive with respect to moist stagnating air and in damp hot climates ; it is, therefore, advisable to keep the lenses, when not in use, in air-tight receptacles. As in former cases we shall also in future in any such cases, where one of the lenses of an objective supplied by us should exhibit spontaneous changes, not hesitate to repair the damage at our cost. To this promise we attacli however the condition that the objective in question be sent to us previous to any attempt being made in this direction by others. In no case should such an objective be disconnected, with a view to clean it, by any other but an expert, as this might suffice to convert a slight irregularity, that could be easily corrected by us, into a serious or even irreparable defect. 11 New Lenses. At the request of eminent niicroscopists we have added to the series of our apochromatric lenses the following types: 1) two objectives of very low p o w e r for the purposes of p h o t o - ni i c r o - graphy (serial sections etc) and for projection on a screen — viz. 70-iiim and 35-mm projection systems; 2) two objectives of large aperture and a shorter focus (for an increased initial amplification) as compared with the older types — viz. 3-mm apochromatic dry system of 0.95 apert. and 1.5-mm apochromatic homogeneous immersion lens of 1.30 apert. ; 3) an objective having the greatest aperture attainable with the present optical means — viz. 2.5-mm monobromide of naphthaline immersion objective of 1.60 apert. ad 1. The systems of 70 and 35 mm focus serve, as stated above, for p h 0 1 0 - m i c r 0 g r a p h y and projection exclusively. Of these the former can only be used in conjunction with the photo-microgr aphic stand, the latter, however, may be used with any of the other stands. The 35-mm lens screws to the lower end of the tube in the usual manner. The 70-mni lens requires a special conical adai)ter, which is supplied with each lens, to insert it into the upper end of the tube. Both are used without eye - pieces. As a condenser it is best to use a convex lens of a suitable focus (price of lens mounted in sleeve M. 5. — ) to concentrate the rays of the source of light upon the objective, so that the pencil of rays emerging from this lens may traverse the object before coming to a focus. 12 In order to predetermine by calculation the aniplitications obtainable from these lenses, the distance of the image (i. e. of the focussing plate) from the ob- jective has to be divided by its focal length, i. e. by 70 and 35 respectively and the quotient so obtained is to be diminished by unity, in accordance with the well known formula. N = ^-l. Prices : Projection lens of 35 mm focus M. 35.— ad 2. The two newly constructed apochromatic objectives of relatively short focus present the same principal features as all the older types of this class of lenses. In particular, they require the use of "Compensating oculars", with this exception, however, that — in consequence of the relatively greater initial ampli- fication of the new systems — the highest numbers of eye-pieces should not be used with them, it being in the case of histological and bacteriological investigations not even advisable to go beyond the No. 8 eye-i)iece. ad 3. In autumn 1880 we constructed a system which sensibly exceeds with regard to defining p o w e r the limits which had existed for the then known objectives whose apertures were of necessity numerically less than the refractive indices of crown-glasses. The objective has an aperture of 1.60 to 1.63 with a focus of 2.5 mm and may satisfactorily be used with the ordinary compensating eye-pieces. The slight traces of colour which are observable near the margin of the field may, if thought necessary, be neutralised by adapting a correcting lens to the eye-pieces No. 8, 12 and 18. Pure monobromide of naphthaline serves as the immersion-fiuid to this objective, and a small bottle of it is supplied with each objective. The specimens have to be covered with carefully polished flint cover-glasses having an exactly calibrated thickness (of ab. 0.17 mm) and must be embedded in media of a refractivity exceeding 1.60 (e. g. monobromide of naphthaline, realgar, iodide of mercury, metliylene-iodide. Smith's medium etc.). When oblique illumination or an illuminating cone having an aperture of more than 1.40 is to be employed, flint slips, a flint-glass condenser and some highly refracting substance connecting both — say monobromide of naphthaline — have to be used. To obviate misconceptions regarding the capabilities of this lens we will not omit to distinctly state that we do not proifer this lens as an improved means of microscopical research directly applicable to the adopted micro-technical methods : 13 it has, on the contrary, been constructed for the purpose of placing in the hands of those specially interested in the development of microscopical technique from an optical point of view, a means of determining to what extent lenses possessing an aperture exceeding the highest aperture obtainable under the usual conditions of application may successfully be used in certain departments of microscopical research. Every advance in this direction necessarily involves an increase of the external dif- ficulties attending the application of the lens; we are, in particular, referring to the preparation of objects ; the difficulties to be surmounted here will be readily appre- ciated if it be remembered that the aperture can never be made to exceed the refractive index of the embedding medium and the cover-glass. Originally only a few specimens of this new objective were made as a purely scientific experiment. The results, however, which have been obtained with it by several microscopists , despite of the difficulties attending its application, have encouraged us in including it in our list of objectives, and we shall continue to make this lens as long as nothing better exists in this direction. A detailed account of the principles of construction of this lens, its mode of application and its capabilities will be found in the Zeitsclir. fiir wiss. Mikroskopie, VI, 1889, p. 417 — 422 (also English translation in pamphlet form), Journ. of the Roy. Microsc. Soc. 1890, p. 11, and H. van Heurck, La nouvelle combinaison optique de Mr. Zeiss et la structure de la valve des diatomees, Anvers 1890. We shall be glad to forward these publications to applicants. CHO. 14 List of the Apochromatic Objectives. Numerical aperture Equivalent focus in mm Initial magnification Price Marks Dry Series 0.30 24.0* 16.0 10.5 15.5 140.— 100.— 0.65 12.0* 8.0 21 31 170 — 130 — 0.95 6.0* 4.0 3.0 42 63 83 220.- 180- 200.— with"' cor- rection collar Water Iinniersion 1.25 2.5 100 300.- with cor- rection collar Homogeneous Immersion 1.30 3.0 2.0 1.5 83 125 167 400 — 400 — 450 — 1.40 3.0 2.0 83 125 500.- 500.— Monobromide of Naplitlialine Immersion 1.60 2.5 100 800.— The last named system is supplied together with 25 fiint cover-glasses and 3 slips of heavy flint. Each additional cover-glass M. 1. — Each additional slip , 2. — Noii-acbromatic Condenser of 1.60 aperture having a flint-glass front-lens to be used with the monobromide of naphthaline immersion lens (for very oblique or wide illuminating pencils) . . . M. 35. — Monobromide of Naphthaline, per bottle containing 5 gr . . ,, 1.50 * The three objectives 24-mm, 12-m,m and 6-mm of the dry series are constructed exclusively for the 10-inch tuhCf all the others are adjusted either for continental or English tube. 15 ^Compensating Eye-pieees. All objectives of considerable aperture, from their peculiar construction (hemispherical fronts) exhibit certain colour defects in the extra -axial portion of the visual field (chromatic difference of the magnification), even if perfectly achro- matic in the centre. The differently coloured images which combine to form the final image (Dippel, 2'"^ ed. p. 225) are of different dimensions, the blue image being greater than the red one. Whether an image be directly projected by such an objective or whether it be examined with an eye-piece (even of the achromatic or so-called aplanatic type), colour fringes will be observed, increasing towards the margin of the field. This peculiarity is also possessed by -the apochromatic objectives, and to the lower power ones it has been intentionally imparted to a similar degree, a means being thereby obtained to nearly entirely eliminate this error by help of suitable eye- pieces. These are made to possess an equivalent error of opposite sign, that is, the image formed by the red rays is greater than that corresponding to the blue rays. Such eye -pieces therefore serve to compensate the unequal magnification of different colours and the images ap])ear free from colour up to the margin of the field. This compensatory action of the eye-pieces is manifested, particularly in the higher numbers where the limiting diaphragm is placed outside the lenses, by the fact that the edge of this diaphragm shows a red border, whilst the image of the object formed at this very edge of the diaphragm is perfectly colourless. The setting- of the eye -pieces is so arranged that the lower focal point of all numbers in each series lies in the same plane when inserted in the body- tube. No alteration of focus is therefore required on changing the eye -piece, and the ''optical tube -length" (i. e. the distance between the upper focal point of the objective and the lower one of the eye-piece), which is the standard factor for the magnifying power, remains constant. This optical tube -length in the continental microscopes (excluding small differences between the various objectives) is 180 mm, provided that tlie length of the body, from the screw -collar of the objective to the upper end of the tube on which the eye-pieces rest, is 100 mm. The eye -pieces of extremely low power designated as Searchers serve the purpose of reducing to its lowest limits the available magnification with each objective, thereby facilitating the preliminary examination and the labour of searching for particular points with high powers. Thus No. 1 of this series enables an objective to be employed with its own 16 initial magnifying power, i. e. as if it were used as a simple lens without an eye-piece. They will be found of special service with immersion objectives, where great inconvenience is caused by having to change a lens already adjusted for another of lower power. The working eye -pieces for regular observation beginning with a magni- fication of 4 are likewise of entirely new construction and may be used with advantage even in the highest numbers. The eye- point in all lies so high above the eye-lens and the diameter of the lens itself is so large, that the usual inconveniences attending the use of eye-pieces of short focus are entirely obviated. Owing to the uniform position of the eye-points of the compensating eye- pieces any one of these may, without difficulty, be used with the usual drawing prisms, including, in particular, the Abbe Camera. The most appropriate for the purpose are naturally the lower powers 4 and 6. The numeration of tliese eye-pieces is carried out on the principle sug- gested by Prof. Abbe. The number which denotes how many times an eye- piece, when used with a given tube-length, increases the initial magnifying power of the objective, aifords the proper measure of the eye- piece magnification and, at the same time, furnishes the figures for rational numeration. On this basis the series of our compensating eye -pieces is arranged according to their magnifying powers, which are respectively 1, 2, 4, G, 8, 12, 18, (27), and these figures likewise serve as their designation. The magnification obtained by combining a compensating eye-piece with any apochromatic objective is arrived at directly by multiplying its number by the initial magnification of the objective as given in the preceding table. An objective of 3.0 mm focus for example yields in itself a magnification of 83.3 (cal- culated for a conventional distance of vision of 250 mm); eye-piece 12 therefore gives with this objective 12X83.3 = 1000. F or the continental and the English model microscopes two distinct series of compensating eye-pieces are made. The corresponding numbers in both series are of a different focal length according to the different lengths of the tubes. The eye -pieces 1 and 6 are only made for the continental, 27 only for the English tube. An order for eye- pieces to be used on stands wldch are not of our make should be accompanied by an exact impression of the edge of tlte tube in sealinff-ivax or some other exact gatir/e of the internal diameter of the tube,' the best gauge, ivill, in all cases, be the tube itself. 17 List of Compensating Eye-pieces. Searcher Eye-pieces Working Eye-pieces Eye-piece No. : 1 2 4 6 8 12 18 1 27 Equivalent focal length in mm 180 90 For t 45 le continental t 30 22.5 ube : 15 10 T'ripp • TVTfirl^''; 20 20 20 20 30 30 25 Equivalent focal length in mm 135 For ()7 the En^ >lisli tu' 34 36 : 22.5 15 10 Price: Marks 25 25 35 30 30 25 Table of Magnifications of the Apochromatic Objectives with the Compensating Eye-pieces for an image distance of 250 mm. Focus of the Searcher Eye-pieces Working Eye-pieces objective 1 2 4 6 8 12 18 27 24.0 16.0 12.0 8.0 6.0 4.0 3.0 2.5 2.0 1.5 15.5 31 62 83 100 125 167 21 31 42 62 83 125 167 200 250 333 42 62 83 125 167 250 333 400 500 667 94 187 372 498 600 750 1000 83 125 167 250 333 500 667 800 1000 1334 125 187 250 375 500 750 1000 1200 1500 2000 187 281 375 562 750 1125 1500 1800 2250 3000 281 562 1125 18 ^Projection Eye-pieees. These are used for projecting the image formed by the objective on a screen for demonstrating purposes or upon a photographic plate. They consist of a convex lens and a compound system, which is most carefully corrected both spherically and chromatically after the principle of apochromatic lenses, and is entirely free from secondary chromatic aberration and from difference of focus between the visual and chemical rays. A diaphragm is placed between the lenses for limiting the field, and the compound lens can be made to approach or recede from this diaphragm. The cap of the projection eye-piece forms a diaphragm by which internal reflexion in the body-tube is entirely ob- viated. The aperture of this diaphragm is made to correspond with the greatest aperture of the apochromatic lenses. The projection eye-pieces are specially corrected for our apochromatic lenses on the principle of the compensating series, but may, nevertheless, be advantageously employed with ordinary achromatic lenses of large aperture. The designation of these eye -pieces corresponds, as in the case of the other compensating eye -pieces, to those amplifications which they would yield (magnifications being measured after the same principle as for the other compen- sating eye-pieces) il used for ocular observation. The magnifications are 2 and 4 for the l()0-mm tube, 3 and 6 for the 2r)0-mm (10") tube. We do not construct projection oculars yielding higher amplifications beyond those indicated as these would not possess a,ny practical advantage over the ordinary compensating eye-pieces, which can be used when higher amplifications are required. Tlie magnification for any distance of image from the eye-piece is obtained, by dividing this distance, expressed in millimeters, by the focal length of the objective in use and multiplying the result by the number of the projection eye- piece employed. Thus the ocjective of i) mm gives with the projection eye-piece 2 an image magnified lOTK) times at a distance of 150 cm. for This rule holds good, strictly speaking, for long distances only; for short distances the figure so obtained is in excess of the true value. The image distance may be reduced in the case of 2 and 3 to about 4( KD mm and with 4 and G to about 250 mm (reckoning from the eye-piece) ; it may, however, be increased to any desired length. For further details see "Specialkatalog fiir Mikrophotographie" (German). Price of the Projection Eye-pieces: 40 Marks each. 19 Aehromatie Objectives. Respecting the general character of these objectives we refer to the remarks on pages 2 and 4 — 6. To the list of achromatic lenses only one new system has been added. At the same time, however, most of the older types of achromatic lenses have been reconstructed with a view to more completely eliminate imperfections due to spherical and chromatic aberration than had been done formerly or — rather — than could have been done without the aid of the new glasses. With the dry lenses DD, E and F this improvement becomes obvious by the clearer appearance of the image and the increased sensibility of the lenses with regard to differences in the thickness of the cover - glass and length of tube. To the achromatic lenses enumerated in our last catalogue we have recently added a water immersion lens of great focal length but having a relatively small ajierture, viz Objective D*. It is calculated to facilitate the examination at medium magnitications (200 to 500 diameters) of living zoophytological objects Hoating in water troughs. Its large focal distance gives to the microscopist a relatively wide range in following the motions of these living objects. The objective being constructed on the water -immersion i)rinciple, i. e. there being always a layer of water interposed between the objective and the cover- glass, the correction of the aberration will not be affected by focussing at various depths of the water-cell, as to a diminution of the stratum of water under the cover-glass always corresponds an increase of the stratum of the water above the cover -glass, and vice versa. This manner of using the lens will, con- sequently, not interfere with the quality of the image. The relatively small aperture is conditional to the great focal distance; for that kind of observation, however, for which the lens is mainly designed this will, owing to the increased depth, constitute rather an advantage than a disadvantage. The system maybe used with or without cover-glass and gives equally good images both with fresh and sea water. 20 The magnificat ions yielded with this objective in conjunction with the Hiiyghenian eye -pieces are the same as in the case of the D and DD ; when used in combination with the compensating eye-pieces it gives nearly the same magnifications as the 4-mm apochroniatic lens of 0.95 aperture (about 9 less). The Olbjectiyes a are simple achromatic lenses, so mounted that, notwith- standing their great focal length, the body of the microscope remains at its ordinary elevation during observation. In the thread is so placed that when screwed home the lens is inside the body; it can, therefore, not be used with a revolving nose-piece or other objective-changer. They are only intended for use with the lower eye-pieces. ObjectiYC a* consists of two achromatic lenses combined after a formula peculiar to us. By means of a ring rotating like a correction collar the two lenses can be approximated or withdrawn, whereby, using one of the lower eye- pieces, the magnification is changeable in the proportion from about 1 to 2. This graduation of the magnifying power is obviously useful for many purposes. We no longer supply the objectives BB, CC; G, K, L (water immersion) and ^/g and ^/^g (hom. immers.) of our former catalogues because their special aim is now, in our opinion, better realised by the apochromatic lenses. All objectives are also supplied adjusted for the 10-inch body and in the English form of mount. Regarding the use of achromatic objectires in conjunction with com- pensating eye-pieces it will be well to state here that only our achromatic objectives from DD upwards, i. e. all those having relatively large aper- tures should be used in that manner. With those of small apertures the use of compensating eye-pieces gives rise to similar errors (though of the inverse chromatic order of succession) in the achromatism of the margin of the field to those effected when apochromatic lenses are being used in conjunction with the ordinary H u y g h e n i a n eye-pieces. Separate maho(jany cases for objectives to he L'ept otitside the microscope case, with loch, accordim/ to si^e 7 to 30 Marks. 21 List of Achromatic Objectives. De- Numerical Equivalent X'rice signation aperture focal length without 1 with correction Marks Dry Series a, — 40mm (1 9_^/;^ 13 — )) 5? a. 35""» (If") 13 — a. — 30mm 13.— 5! )5 ■ a* — 38-36'"'" (li"— 1") 40.— aa 0.17 37.— !; A 0.30 18mm (|//^ 34.— A A AA A OA QA oU. — " " B 0.35 13"™ (i'O 30.- C 0.40 7mm (.^9^/-) 36.— D 0.65 4.3""" (1") 43.— DD 0.85 4.3'"'" il") 54.— 74 — r 0.85 O ^, Oftijdvc Wc^^taU^, Sena. 108 No. 84 Dissecting Lens after Brucke, double objective with achro- matic lenses of 33 mm aperture and sliding eye-piece, magnifying 5 to 10 times The above two numbers are specially designed for the lens holders Nos. I and II. Hand Magnifiers. 87 Achromatic Magnifier, in ivory mount to fold, as above, with two achromatic lenses; magnifying 3, 5 and 8 109 Synopsis of Magnifiers. No. Type Magni- fication i \J\ji mm : a) white crown-glass witli ground edges, per 100 . . unground edges, per KK) . c) best white phite-glass witli ground edges, per W Hollow Slips: a) small pattern, 5r)X">2 nnn, of l)est make and finish, ground edges, each b) extra large, 87 X-^'^ best make and finish, edges ground and polished, 5 mm thick, each Slips with cemented glass rings, for moist chambers 1 or 2 mm deep, each 0.80 Covers square: size : 24 21 18 15 12 mm □ per 100 Mk.: 470 3.60 2.70 1.80 1.-. 114 No. 99 Covers, round: 24 size 21 18 15 12 mm diameter per 100 Mk. : 6.90 5.50 4.20 3.00 1.50. Marks 24 M5 100 Covers, oblong: size : 32X24 mm per 100 Mk. : ~aOO and 24X21 mm 4.507 32X24MHi 24X21MB The thickness of the above covers varies between 0.15 and 0.22 mm; one third more must be added to the above prices for covers of given thickness. Complete Microscopes. For the convenience of the buyer we have compiled the following series of suitable and current combinations with the total price appended. In ordering either of these sets it will be sufficient to quote the respective number and price. 1) Microscope: stand I* with mechanical stage M. 400. Apochromatic Objectives : 16.0 mm, 8.0 mm, 4.0 mm 0. 30 n. ap. 0.65 n. ap. 0.95 n. ap. 100 — 130.— 180.— M. 410. — 2.5 mm (Water Immers.) 1.25 D. ap. 300.— „ 300 — 2.0 mm, 3.0 mm (Homog. Immers.) 1.30 n. ap. 1.40 n. ap. 400.— 500.— n 900— „ 1610. Compensating Eye-pieces : 1, 2, 4, 8, 12, 18 20 — 20.— 20.— 30.— 30.— 25.— „ 145 — 6 with ^/j^ micron divisions (Micrometer Eye-piece No, 29) ,, 30. — Projection Eye-pieces: 2. 4 40. — 40. — „ 80. — Goniometer Eye-piece No. 40 ,, 30. — 285.- Carry forward M. 2295. 116_ HiouKlit forward M. 2295. — Apertometer No. 2 M. 80.— Test-plate No. 3 10. — Sliding Objective-changer No. 25 with 6 Objective-slides ,, 70.- Case for 6 slides 7- — Stage Micrometer No. 26 10.— Screw Micrometer Eye-piece No. 30'' 80.— Stage Screw Micrometer No. 31 . . . . . ,, 120. — Crossed-line Micrometer No. 32 „ 5- — Apparatus for counting blood corpuscles No. 34*: 44. — Measures No. 36 and 37, 100 and 300 mm respectively ,, 10. 50 Fully divided Circle No. 39, 120 mm dia , 9.— Cover-glass Tester No. 41 „ 36. — Camera No. 44 42. — Polariscope No. 48^ (Divided Circle of the Goniometer Eye-piece No. 40) 39- — Series of Selenite and Mica Films No. 51 „ 10 — Spectroscopic Eye-piece No. 53 • " ^^S — Microscope Lamp No. 59 . . ,, 30. — Saccharimeter No. 61 . . . „ 65. — Turn Table No. 63 m 9 — Apparatus for Mounthiy. Dissecting Microscope : Dissecting Stand I ■ ., lOO.— Dissecting Series No. 76 . . . . ,, 40. — Aplanatic Lenses No. 79, )><^ 6 and 10 . . a 15 — ■• 30- — „ 170 Lens Holder I „ 25 — with Brucke's Lenses No. 83 and 84 41. — 66. — Microtome No. 89*) „ 40.— Extra Knife No. 92 . . . 5 — ,, 45. — Packing 8 50 j^j^^ 3^2«. 2) Microscope: Stand I'l without mechanical State M. 30O.— Apochromatic Objectives : 16.0 mm, 8.0 mm, 3.0 mm 0.30 n. ap. 0.65 n. ap. O.95 n. ap. 100. — 130. — 200.— M. 430.— 2.5 mm (Water Immers.) 1.25 n. ap. 300.— „ 300 — 1.5 mm (Homog. Immers.) 1.30 n. ap. 450— M 450— „ I180.— Carry forward M. 1480.— *) We are prepared to supply larger microtomes at manufacturer's prices (vide remark p. 111). 117 Brought forward M. 1480. — Compensating Eye-pieces: 2. 4, 8. 12, 18 20.— 2oT^ 30.- 30^ 25.— M 125.— 6 with ^/'^ micron divisions (^Micrometer Eye-piece No. 29) 30- — Revolving Nose-piece No. 24c n 35- — Stage Micrometer No. 26 „ lO- — Cover-glass Tester No. 41 >» 3^- — Camera No. 44 n 42- — Polariscope No. 48^1 1. 54- — Series of Selenite and Mica Films No. 51 lO- — Apparatus for Mounting : Dissecting Microscope: Dissecting Stand I „ lOO. — Dissecting Series No. 76 40. — Aplanatic Lenses No. 79, X ^ '° • • • ^S-— 3°- — 170.- ^^''^^^S 4- M. 1996.- 3) Microscope: Stand Ila M. 290.— Attachable mechanical Stage ,■, 75 — ^ Apochromatic Objectives : 16.0 mm 8.0 mm 4.0 mm 0.30 n. ap. 0.65 n. ap. O.95 n. ap. 100.— 130. — 180. — „ 410 — 2.0 mm (Homog. Immer.'iion) / ^j. 3-0 \ 1.40 n. ap. V 1.40 n. ap./ . . 500 — 910.- Compensating Eye-pieces : 2, 4, 8, 12, 20. — 20. — 30. — 30. — 100. — 6 with 7i micron divisions (Micrometer Eye-piece No. 29) 30. — _ Sliding Objective-changer No. 25 with 4 Objective-slides „ 50 — Case for 6 slides ?< 7- — Camera No. 44 „ 42. — Polariscope No. 48^ » 54' — 1=;^.- Apparatus for Mounting : Dissecting Microscope : Dissecting Stand III ,, 50 Dissecting Series No. 76 ,, 40 Aplanatic Lenses No. 79, X ^ ^""^ ^° • • ^ I5-— n 3^ Extra Lens Holder for use with Diss. Stand III . . ,, 5 Lens Holder I „ 25 with Bruckk's Lens No. 83 „ il Hand Microtome No. 90 ,, 18 with Knife No. 92 ,, 5 Packing I25-— 36— 23-— M. 1745.50 118 4) Microscope: Apochromatic Objectives : 16.0 mm 8.0 mm 4.0 mm 0.30 n. ap. 0.65 n. ap. 0.95 n. ap. 100.— 130.— 180.— M. 410. 2.0 mm (Homog. Immers.) 1.30 n. ap „ 400.- Compensating Eye-pieces : 2, 4, 8, 12 20. — 20. — 30. — 30. — „ 100.- 6 with micron divisions (Micrometer Eye-piece No. 29) „ 30.- Sliding Objective - changer No. 25 with 4 Objective- slides „ 50.- Case for 6 slides „ 7.- Stage Micrometer No. 26 ,, 10. Camera No. 44 „ 42.- This outfit costs with: a) Stand !» with mechanical Stage Packing or b) Stand Ila Attachable mechanical Stage Packing or c) Stand IVa Iris Diaphragm Attachable mechanical Stage Packing 5) Microscope: Apochromatic Objectives : 16.0 mm 3.0 mm 0.30 n. ap. 0.95 n. ap. 100.— 200.— M. 300.- 1.5 mm (Homog. Immers.) 1-30 n- ap , „ 450 - Compensating Eye-pieces: 2, 4, 8, 12 20 — 20. — 30. — 30.— „ lOO.- 6 with Yj micron divisions (Micrometer Eye-piece No. 29) ,, 30. Revolving Nose-piece No. 24^ 27.- This outfit costs with : a) Stand I* without mechanical Stage with „ „ Packing or b) Stand Ila Packing or c) Stand IVa Iris Diaphragm Attachable mechanical Stage Packing M. 1049.— M. 400 — 3-50 M. 1452.50 „ 290.— 75— 3- M. 1417.- 200. — 15— 75-- ^~ M. 1342.- M. 907. — M. 300. — „ 100.— 3-- „ 290.— 2.— M. 1310.— M. 1199. 200.— 15- 75-- M. 1199.50 119 6) Microscope {Outfit of the Prussian Military Hospitals) : Achromatic Dry Objectives: AA, DD 30— 54-— M. 84.- Apochromatic Homog Immers. Objective: 2.0 mm 1-30 n. ap Huyghenian Eye-pieces: 2' 4 k 7.— „ 14.. Compensating Eye-pieces : 4. 8_ " 50- 6 with micron divisions (Micrometer Eye-piece No. 29) „ 30.- Revolving Nose-piece No. 24b 27.- This outfit costs with: a) Stand la without mechanical Stage Packing or b) Stand 11^ Packing or c) Stand IVa Iris Diaphragm Attach ablemechanicalStage Packing 7) Microscope: Achromatic Objectives : A, Cj B 24— 36— 66.- M. 126.- ^Il2 ^'3° ^P- (Homog. Immers.) „ 300.- Huyghenian Eye-pieces: 2. 4 ,. 14.- 3 with Micrometer (Micrometer Eye-piece No. 28) . . ,, 15.- Revolving Nose-piece No. 24c 2^ _ Camera No. 44 ^2 - This outfit costs with : a) Stand la without mechanical Stage Packing or b) Stand Ila Packing or c) Stand IV* Iris Diaphragm Packing 8) Microscope: Achromatic Objectives : a«, A, C, P 12.— 24.— 36.— 84.— „ 156.- Carry forward M. 156.— M. 605. 300.— 290. — 2. — M. 532.— „ 300.— _n 3^ „ 290 M 2, — „ 200 „ 15— » 2.— M. 908. M. 897 200. — 75- — M. 897.60 M. 835.- M. 824.- M. 749.- cna. 120 Brought forward M. 156 — Water Immers. Objectives: D% J ,, 219. — Huyghenian Eye-pieces: 2, 4 k Mk. 7— „ I4-— 3 with Eye-piece Micrometer (Micrometer Eye-piece No. 28) „ 15- — Revolving Nose-piece No. 24!^ " ~ Camera No. 44 ^1 — A^lIU M. 473 — This outfit costs with: a) Stand without mechanical Stage " 300.— Packing 3-— m. 776.— or b) Stand Ila " ^90-— Packing " M. 765.— „ 200.- c) Stand IVa I c. — Iris Diaphragm ' Packing M. 690.— .9) Microscope {greatly patronized hy physicians, surgeons and veterinarians) : Achromatic Objectives: AA, DD ' . . . . M. 84.— 30.— 54.— ^ ^|,_ 1.20 (Homog. Immers.) " 160 — Huyghenian Eye-pieces: 2, 4 a Mk. 7.- „ I4-- Eevolving Nose-piece No 24b . ^7-Il_ M. 285.— This outfit, representing according to Prof. Koch of Berlin the minimum required for bacteriological in- vestigations, costs with: a) Stand I* without mechanical Stage " 3°° Packing - 3 — m. 588.— or 2QO. — b) Stand Packing » ^ ~~ M. 577.- or ,1 200.— c) Stand IVa IV — Iris Diaphragm Packing " M. 502.- 10) Microscope {for the same purposes, hd a little cheaper than outfit 9): Achromatic Objectives : A, D ' . . . M. 66.— 24- 42— 1.20 (Homog. Immers.) " l^c- I Huyghenian Eye-pieces: 2, 4 Mk. 7— M H- Revolving Nose-piece No. 24b . . . . . . • • • • ^7j— 267.— 121 f his outfit costs with : a) Stand la without mechanical Stage M. 300. — Packing ,, 3. — or " ~ b) Stand II* „ 290.— Paclcing „ 2. — c) Stand IV* „ 200.— Iris Diaphragm 15. — Packing „ 2. — 5r d) Stand IVb ,,150.— Illuminating Apparatus No. 18 with Iris Diaphragm . ,,40.— Packing ,, 2. — e) Stand (see remark on p. 46 regarding applicability of immers. systems with these stands) 120. — Iris Diaphragm 15. — Packing ,, 2 or f) Stand VII (see remark on p. 46 regarding applicability of immers. systems with these stands) ,, 60 - Illuminating Apparatus No. 19 „ 10. — Small Iris Diaphragm „ 12.— Packing „ 1.20 11) Microscope: Achromatic Dry Objectives: A, D, F 24.— 42. — 84.— M. 150.— Hnyghenian Eye-pieces: 2, 4 ^ Mk. 7. — ,, 14 — Bevolving Nose-piece No. 24!) ,. 27 — This outfit costs with: a) Stand IVa „ 200.— Iris Diaphragm „ 15. — Packing „ 1.80 or b) Stand IVb ,,150.— Packing ,, i 80 c) Stand Vn ,,120. — Packing ,, 1.80 d) Stand VI ,,65. Packing „ I . 12) Microscope: Achromatic Dry Systems: A, C, B 24.— 36. — 66. — M. 126.— Huygbenian Eye-pieces: 2, 4 k M. 7.— „ 14.- Revolving Nose-piece No. 2/^^ ,, 27. — ^ This outfit costs with : a) Stand IVa 200. — Iris Diaphragm 1, 15- — Packing „ 1. 80 ina. M 670,— M. 559,— M 484.— M 459.— M. 404.— M. 360.20 M. 407.80 M 342.80 M. 312.80 M. 257.- M. 383.80 122 or b) Stand IVb M. 150.— Packing „ 1.80 or c) Stand Va „ 120 — Packing „ 1.80 d) Stand VII „ 60.— Packing „ I. — M. 318.80 M. 288.80 M. 228.— IS) Microscope : Achromatic Dry Objectives: a^ B, D 12. — 30. — 42. — M. 84.— Hnyghenian Eye-pieces: 2. 4 7—__^ HlH M. 98. This outfit costs with : a) Stand VII „ 60. Packing „ I. M. 169.— b) Stand IX ,,40.— Packing ,, 1.20 M. 139.20 or c) Hand Microscope No. 16 15 — P*'^'^"'^ _21 = M. 113.- 14) Microscope for the detection of Trichina after Professor Johne : Stand IX with specially constructed Triple Objective and 2 Eye-pieces; 6 Amplifications from 30 — 190 .... „ 70. — ''^^'^'"g ^ ^ M. 71.20 Index. pape a, a*, A, AA-Objectives . . 20—22 Achromatic Objectives . . . 19—22 „ „ combined with. Compensating Eye-pieces , 20 Accessory arrangements for testing the fundamental properties of microscopical objectives . 24 — 25 Apertometer 24 Adjustment, coarse, fine .... 29 Analysers and Polarisers ... 80 Apochromatic Objectives : Introduction of the „ . . . , 1 Properties of the „ . . . 7 — 11 Durability of the „ .... 10 New constructions .... 11 — 13 Price list 14 Magnifications with the Compen- sating Eye-pieces . . . 16 — 17 Apparatus for counting blood corpuscles after Thoma . . . 75 Apparatus for photo-micro- graphy 92—99 Arc lamp, electrical 96 Arrangements for polarisation 79 — 80 Axial images , Eye - piece for ob- servation of 56, 80 B-Objective 21—22 BB-Objective 20 Babuchin, Stands .... 42—45 Bertrand's Eye-piece 56 page Bull's Eye Lenses 87 Browning, Hand Spectroscope after 87 Body-length for which the ob- jectives are adjusted 4 — of the stands 30 C Objective 21—22 CC-Objective 20 Camera lucida . . . . 56, 77 — 78 Cap bottles for immersion oil . . 21 Cases for the stands 31 Cedar-wood oil 21 Centering Arrangement for the illu- minating apparatus .... 59, 61 Circles, fully divided 76 Clamping ring 48 Compensating Eye-pieces . 15 — 17 Condenser, achromatic 62 Condenser systems ... 14, 58, 61 Correction of the spherical and chromatic aberrations . . 1, 5, 7, 8 Correction Adjustment .... 5 Covers 14, 113—114 Cover-glass gauge 76 Crossed-line Micrometer .... 74 Crossed-line Stage Micrometer , 74 Cylinder diaphragms . 30, 32, 58, 61 D, DD, D*-Objectives . . 19—22 Diaphragms to insert in the Eye- pieces after Ehrlich 74 124 page Diffraction Plate after Abbe 86 — 87 Distance of object 4 Dissecting knives etc., set of . .111 „ lenses 106 stands .... 100—104 Divided Circles 76 Drawing apparatus ... 56, 77 — 78 Draw Tubes with millimeter scale 29 E-Objective 21—22 Engelmann , Micro - spectral Ob- jective 64 Micro-spectral Photometer Eye-pieces : Axial-image „ Bertrand's „ Compensating „ Huyghenian „ Orthoscopic „ Projection „ Stereoscopic „ Spectroscopic „ Setting of Eye-pieces Numeration „ Eye-piece Micrometer Engraving of names on stand . 82 56, 80 . 56 15—17 22—23, 56 23 18 85 , 81 . 15 . 16 56, 70 . 31 56 F-Objective 21—22 G -Objective (Water Immersion) . 20 Glass globe with stand .... 87 Goniometer Eye-piece . . .56, 76 H-Objective (Water Immersion) 21 — 22 Haemacytometer after Thoma . . 75 Hand Microscope 48 Hand Spectroscope after Browning 87 Heating arrangement for warming microscopical objects 88 Huyghenian Eye-pieces 22 — 23 — with crossed lines 56 Homogeneous Immersion: Objectives for „ ... 6, 14, 21 Pluid for 6, 21 page l-Objective (Water Immersion) 21 — 22 Illumination of the objects ... 30 Illuminating apparatus : for white light 30 for spectroscopically decomposed light 63 for monochromatic light after Hartnack 63 after Abbe 57 — 61 simplified 61 small of 1.0 ap 61 Image distance of the Projection Eye-pieces 18 Immersion fluid 6 Immersion Objectives, achromatic 6, 21 „ „ apochromatic 6, 14 Iris diaphragm 60 — 61 K-Objective (Water Immersion) . . 20 Knife for microtomes Ill L-Objective 20 Leather travelling cases . . . . 31 Lenses 106—109 Lens Holders 105 Magnification : Initial magnification of the Apo- chromatic Objectives , . . 9, 14 Eye-piece magnification . 16, 17, 23 Magnifiers 106—109 Mahogany cases for objectives . . 20 Measure on brass 75 „ „ plate-glass 76 Measuring and counting apparatus 70 Measuring Eye-pieces . . . 71 — 73 Metal name plates 31 Micro-burner 90 Micrometer movement of the stands 29 Micrometer : Stage Micrometer ] } 70 Eye-piece „ j Stage Screw Micrometer ... 73 Screw Micrometer Eye-piece . 56, 73 Crossed-line Micrometer ... 74 Crossed-line Stage Micrometer . 74 125 page Micrometer Eye-piece . . . . 56, 71 Microscope Lamp 87 Micro-spectral Objective after Engel- MANN 64 Micro-spectral Photometer . . 56, 82 Microtomes 110 — 111 Monobromide of Naphthaline . . 14 Nachet, reversing prism .... 86 Objectives : General Properties . . . 1 — 3, 4 — 6 Achromatic Objectives . . 19 — 22 Apochromatic „ ... 7 — 14 Changing arrangements for „ 67^ — 69 Objective magniflcation ... 9, 14 Photo-micrography : Apparatus for „ . . . . 92 — 99 Stand for „ 36 Polarisation arrangements . 79 — 80 Projection apparatus . . . 92 — 99 Eye-pieces 18 „ Systems .... 11 — 12 Reversing prism after Nachet . . 86 Revolving nose-piece 68 RoUet, Spectro-Polariser after . . 66 Saccharimeter 88 Screw Micrometer Eye-piece 56, 73 Series of Selenite and Mica films 56, 80 Sliding Objective-changer . 68—69 Slips 14, 112— 113 Sliding Ruler 91 Specimens, microscopical . . . .111 Specialkatalog of photo-micrography 92 page Spectroscopic Eye -pieces 56, 81 — 84 Spectro-polariser after Rollet . . 66 Spectroscope, Hand-after Browning 87 Standard Thread 6 Stage Micrometer 70 Stages : General remarks .... 26 — 28 Mechanical Stage for Stand F . 34 Attachable, mechanical stage . . 90 Stands : General remarks . . , . 26 — 31 Large Stands 32 37 Medium „ ..... 38—45 Small „ 46—48 for crystallographic and petrological researches 50 — 55 Stauroscopic Plate 56 Stops for Eye-pieces 74 Table of Magnifications of the Apochromatic Objectives with the Compensating Eye-pieces 1 7 of the Achromatic Objectives with the Huyghenian Eye-pieces . . 22 Test-plate after Abbe . . . . . 25 Test-tube holder 91 Thickness of Cover, for which the Objectives are corrected ... 5 — Measurement of the same by means of the Micrometer screw ... 29 Thoma, Haemacytometer after . . 75 Trichina, Microscope for dissecting 48 Turn Table (Tournettej .... 90 Working Distance 4 Working Eye-pieces 16 Warm Chamber 88 Hennann Polile, Hotbuclidruckerei, Jena. — 1 140