作者：Leitz, Ernst
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Microscopes and Accessory Apparatus Catalogue No. 40试读：
Notice.
All previous editions of this catalogue are superceded by the present one, which should be exclusively used in ordering.
Orders will be filled at once after their receipt.
In ordering care should be taken to give the number of each article desired and to state listprice.
To avoid delay and misunderstandings, we request that name and address be plainly written.
Goods are forwarded at the expense and risk of the purchaser.
Our instruments for use in Universities, Colleges, Schools &c. of the United States are by law free of duty and we shall be pleased to make specially low quotations for such orders.ERNST LEITZ.
New Constructions.
Since issueing our last catalogue, a number of new apparatus and accessories have been added. The following are the more important ones:
1. A completely new stand "A" with extra fine micrometerscrew transmitting its movement directly to the tube. The stand is of elegant appearance and large dimensions, making it especially well adapted for work in photo-micrography.
2. Stand I is now fitted out with the new special fine adjustment (each division 1/1000 mm).
3. Stand II with round centering stage.
4. Stand IV is replaced by a model of larger size.
5. Photo-micrographic apparatus for use in horizontal and vertical position, having joint for inclination, large size bellows and plateholder.
6. Large projection-apparatus for electric lamp of 30 Ampère with triple collecting lens of 210 mm aperture.
7. Objective 1 a with adjustable mounting and changeable magnification. It is an excellent objective of low power for general purposes, having a comparatively short working distance.
8. Objective 1 b with changeable magnification of lowest power, as far down as two diameters. It serves for drawing extended sections and specimens.
9. Saccharimeter after Mitcherlich improved form.
10. Trichinoscope, projection-apparatus of strong and simple construction.
Preface.
Our American Branch house in New-York under the management of Mr. Wm. Krafft has now been established for over 10 years. This period has witnessed a gradual development of our business in the United States, making it necessary to establish some years ago a Western Branch in Chicago of which Mr. R. Gibson has charge.
The cordial reception our firm received has been most gratifying and we take this opportunity to thank our many patrons for their kind consideration.
It is our aim to co-operate with the scientists and construct new apparatus to meet their needs or improve others wherever this is possible.
The foregoing list of additions and improvements made since issueing our last catalogue is proof that we spare no time nor labor to hold pace with the increased wants of modern times.
We have now manufactured and sold over 71000 compound microscopes and 31000 oil immersion objectives, a large number of which are used in the laboratories of Universities, Colleges, and other Educational Institutions of the United States.
We are prepared at New-York and Chicago to repair our instruments or make alterations at short notice and at lowest prices. The optical part of a microscope should invariably be sent to the maker, as he is best in a position to repair same and has an added interest to bring a lens back to its original quality or even improve it.
Microscopes, bacteriological apparatus and all other scientific instruments or preparations expressly imported for use in educational institutions are exempt from duty.
Catalogues may be had on application by addressing:
ERNST LEITZ,
NEW-YORK CHICAGO411 West 59th Street 32 Clark, Cor. Lake Street.Objectives and Eye-pieces.
In the manufacture of our objectives only such glass is employed as has been subjected to the most rigid scientific tests. By these the exact index of refraction and the exact degree of dispersion of the glass are determined, and with these data available it is possible to very perfectly correct both spherical and chromatic aberrations while still making use of wide angular apertures in the objectives.
The precise mathematical calculation, combined with accurate systematical working and testing methods, make it possible for us to guarantee our objectives to be all of equal and excellent quality.
Every objective before leaving our hands, is subjected to the most careful test, and only such lenses as are of the highest grade, are sent out.
For the past seventeen years we have used glasses manufactured by Schott & Co. of Jena. This glass has many points to recommend it for the construction of optical instruments, and only such kinds are employed by us, which have for many years been thoroughly tested as to their durability.
Our lenses are therefore absolutely permanent. Objectives of the earlier type which have become cloudy, we shall gladly repair.
The three illustrations given above afford an idea of the plan of construction of our achromatic objectives.
The first figure represents the plan of our low power objectives, and it will be noted that they consist of two doublets, or triplets each carefully corrected.
The central figure shows the construction of our high power dry objectives. A hemispherical front lens is combined with two doublets or sometimes triplets. The front lens is the chief magnifier of the combination, while the other lenses serve to correct the various aberrations.
The Oil-immersion, represented by the last illustration consists of a front lens, hemispherical, behind which is a meniscus, which is in turn followed by a doublet and a triplet, these latter acting as the correcting lenses of the combination.
We manufacture both Achromatic and Apochromatic objectives. They differ in that the glasses made use of in the apochromatics and the manner in which they are combined permit a more perfect correction of chromatic aberration. This advantage is not gained without a certain sacrifice of simplicity in construction; by avoiding the use of flint glass having a high refractive index and substituting materials to take the place of crownglass. The apochromatics as a matter of fact do resolve the fine markings of test objects (butterfly scales and diatomes) somewhat more clearly than the achromatics, but the difference is slight and in ordinary stained microscope preparations is hardly detectable.
The correction of both achromatics and apochromatics is complete. The ordinary Huyghenian eye-pieces are consequently well adapted for use with the objectives of either construction. Only with the highest powers is it desirable to make use of the so-called "compensation" eye-pieces.
The achromatics and Huyghenian eye-pieces are also well adapted to the requirements of photomicrography, special objectives being unnecessary for this purpose. This statement is substantiated by the excellent results obtained with our achromatic objectives, as shown in the photomicrographs accompanying our brochure on Photomicrography:—"Anleitung zur Mikrophotographie".
In making use of the higher power objectives—from No. 5 on—it should be remembered, that the lenses are corrected for cover glasses of 0,17 mm in thickness and for a microscope tube-length of 170 mm. When using the oil-immersion objectives it is particularly desirable, that this exact tube length should be employed. With a view to facilitate the adjustment of the tube-length the draw tubes of all our larger stands are graduated in millimeters, the scale indicating the exact length of the microscope tube in any given position of the draw tube. In this connection it should be remembered, that the width of the collar of the nose-pieces is 15 millimeters, and that consequently, when a nose-piece is attached to the tube the reading of the draw tube scale should be 155 mm instead of 170 when the adjustment is proper.Figure comparative merits of the dry and immersion systems.
The above sketch may serve to make clear the advantages of the immersion objectives over those of the dry series. It is intended to represent diagrammatically a section through a cover-glass and the front lens of an objective, one half of the figure representing the conditions present in the case of the Oil-immersion, the other those which are present in the dry objectives. It will be noticed that by the interposition of a drop of oil of the same index of refraction as the glass between the cover-glass and the objective the refraction which occurs in the dry system when the light leaves the upper surface of the cover-glass is done away with. Since this second refraction is attended with much loss of light it must be evident, that in the immersion system a much greater quantity of light enters the objective than is possible, other things being equal, in objectives of the dry system.
If we let u represent one half the angular aperture of an objective, represented in the diagram by D'BN in the case of the immersion, and n the index of refraction of the medium interposed between the cover-glass and the objective we have in the formula n sin. u a mathematical expression of the optic power of the various systems of lenses, or in other words for what is designated the numerical aperture.
The following table gives the numerical apertures of objectives of the various systems and of various angular apertures. In the dry system n., representing the index of refraction of air is taken as 1.00; in the immersion systems n equals 1.33 for water, 1.52 for cedar oil and 1.66 for monobromnaphthalin. A glance at the table will suffice to show the great advantage which the immersion objectives have over those of the dry series.Angular102030405060708090100°110°120°130°140°uaperture 2 °°°°°°°°°Numerical apertures.Dry series0,00,10,20,30,40,50,50,60,70,70,80,80,90,9 = 1,00n98642074172714Water-Immersion0,10,20,30,40,50,60,70,80,91,01,01,11,21,2 = 1,33n24566665429505Homogeneous Oil-0,10,20,40,50,60,70,80,91,01,11,21,31,31,4Immersion46024678764283 = 1,52nMonobromide of0,10,20,40,50,70,80,91,01,11,21,31,41,51,5Naphthaline-Immersion59370357776406 = 1,66nPhotographic objectives with iris diaphragms, f/3.5Focal length mm64423524Price $20181818
Objective 1b.
It is designed principally for drawing extended sections and large specimens, and consists of two adjustable doublets. By varying their distance, a changeable magnification down to two diameters may be obtained.
Price $8.—
Huyghenian Eye-pieces.
Number0IIIIIIIVVFocal length mm504035302520Price of each eyepiece $ 2.00.The objectives designed for the Edinger apparatus of 64, 42, 35, and 24 mm focal distance have been found to be very useful for a number of purposes and have come into great favor.
(see. Dr. Kaiserling: Praktikum der wissenschaftlichen Photographie p. 263).
Achromatic Objectives.
MicroNumerical Focal meter PriceNo. of ObjectiveAperturelength$ Value(num. aper.) s{ 1*{ 1 44 0,054 Low power { 1amm 0,09mm = [1]3.25(1-3/Dry Series { 2 54µ4"){ 3 { 4 44 0,054 mm mm = 0,096(1-3/54µ4") 10(adjusta50—39-27 ble 0,06—0,1026µmmmounting)30 0,028 mm 0,14mm = 6(1-1/28µ4")18 0,015 mm 0,28mm = 6(3/4)16µ0,009 8 mm 0,55mm 10(1/3)= 9µHigh power { 5 { 6 (Fluorite) { 6a5,8 0,004mm 0,775 mm { 7 10(1/4")= 4,5µ(Fluorite) { 7a" { 8 " { 9 4,4 0,003mm 4 mm 0,8212(1/6")= 3,5µ4,4 0,003mm 4 mm [2]0,8216(1/6")= 3,5µ3,2 0,002mm 0,856 mm 12(1/8")= 2,6µ3,2 0,002mm 0,856 mm [2]16(1/8")= 2,6µ2,5 0,002mm 0 mm 0,8716(1/10")= 2,0µ2,2 0,001mm 0,877 mm 24(1/12")= 1,7µ2,2 0,001Water-Immersion 10mm 7 mm 1,1026(1/12")= 1,7µ{ 1/102,5 0,002mm 1,302 mm Homogeneous Oil-Immersion { 1/1230(1/10")= 2,2µ{ 1/162,1 0,001mm 7 mm 1,3040(1/12")= 1,7µ1,7 0,001mm 1,304 mm 60(1/16")= 1,4µ[1] Objective 1* consists of only one doublet, carefully corrected. It is sufficient for many purposes, though it does not possess the same brilliancy of field as the No. 1 objective.
[2] The objectives 6a. and 7a. are better corrected in achromatism than the regular No. 6 and 7.
Magnification
of the Achromatic and Apochromatic Objectives in combination with the Huyghenian Eye-pieces.Tube-length 170 mm. Distance of image 250 mm.ObjectivesEye-piecesObjectives 0 I IIIIIIV V{ 1* { 1 Low power { 1a Objectives { 2 { 3 { 4 Achromatics121822263040 121822263040111318246-9--1-2-2-391591952533405060801013456070805010111318237505500High Power { 5 Objectives { 6 and 6a141821253242(Cover-glass { 7 and 7a000050thickness { 8 0,17 mm) { 9 2025303546600500002633404560780500003040455570940000003850577090110050050Water-Immersion { 104053617495125505000Homogeneous { 1/10314147577394Oil- { 1/12050500Immersion { 1/164355658010135500000052708095121600005080{ 161114Dry Lenses { 8 Apochromatics4560708500{ 4 12141722299555055212731375063005505Oil-Immersion 23951587092110055080Apochromatic Objectives.
NumericFocal MicromealPriceObjectives lengthter$AperturmmValuese{ 160,015 0,30Dry Series { 8 1624mm{ 4 0,007 0,65832mm48with 0,003 0,954correction mmcollarHomogeneous 0,002 1,302100Oil-Immersion mm{ 2Compensation Eye-pieces.
for Apochromatic Objectives.Eye-pieces 4681218Price $6.506.5010108Compensation Eye-piece 6 with micrometer $8.50Magnification
of the Apochromatic Objectives in combination with the Compensation Eye-pieces.ObjectivesEye-pieces4681218{ 1610Dry Series { 8 701251552250{ 4 1420260325465003043100550675000Oil-Immersion 2 578210815022550000Double revolving Eye-piece.Until very recently we have manufactured no arrangement for changing oculars on the microscope. This was due in part to the fact that there was no great demand for such an accessory and in part to the clumsiness of all those revolving eye-pieces which changed the entire ocular. The latter of these difficulties has been overcome in our present revolving eye-piece by such an adjustment of the collecting or lower lens of the eye-piece that it may remain permanently in position, the eye lens of the combination alone moving in the revolver. So accurate is the construction of the revolver and so carefully are the lenses adjusted that the eye-pieces may be changed while a specimen is in focus on the microscope stage without a readjustment of the focus.
The revolving eye-piece is also particularly well adapted to use as a micrometer ocular, for when the eye lens is turned aside a micrometer scale may be inserted and rests upon the diaphragm of the eye-piece. Once adjusted in this way the micrometer values are the same for all the eye lenses of the combination.Double revolving Eye-piece, Prices: 4.—$without eye lenses Each eye lens1.25$Eye-piece Micrometer, No. 86 2.—$
Stands.
For the past thirty years division of labor has been employed to the utmost possible extent in the manufacture of our microscopes. This principle has been applied to our machinery as well as to our workmen, with the result that we have gradually accumulated a large plant of special machinery of the most accurate construction, each machine especially adapted to the manufacture of some particular part of our microscopes. By this development of mechanical appliances for microscope manufacture two ends have been attained:—The greatest accuracy and uniformity of construction of our microscopes has been made possible, while at the same time it has been possible to cheapen the cost of manufacture. Instruments which are the product of delicate machinery must always be more uniform, more accurate and should be less costly than those manufactured by hand.
In the following remarks we refer more particularly to the larger microscope stands of our manufacture and draw attention to those parts which should be present in every well equipped microscope.
The elements of these microscopes are:
1. The foot and upright support with joint for inclination,2. The stage,3. The sub-stage, with condenser, iris diaphragm and mirror,4. The body with the adjustments,5. The tube, carrying eye-piece, nose-piece and objectives.
1. The foot and upright support are solid and are of such weight and shape as to permit inclination of the body of the microscope to a horizontal position. The foot is horse-shoe shaped and is made to touch the table at three points, thus insuring stability even on a surface which is not entirely level. Inclination of the body of the microscope is permitted by a joint in the upright, which joint may be fastened in the larger stands by a set-screw operated by a lever. Stands Ia and IIb are also made with the English foot. Abundant space is left under the stage for the various attachments of the sub-stage.
2. The stage of Stands A, I, Ia and II is round, revolving and centering. The centering arrangement consists of two small thumb-screws so situated at the sides of the stage as to control motion of the stage in all directions, thus to a limited extent serving the purpose of a mechanical stage.
The other microscope stands have square immovable stages, sufficiently large for general microscopic work. For the examination of very large sections two instruments are manufactured: the Nebelthau sliding microscope (p. 50) and the stand after Dölken (p. 52). The former is for magnifications up to 120 diam, whereas the latter can be used with any magnification.
3. The sub-stage carries a plane and concave mirror, the condenser and the diaphragm for regulating the illumination of the object.
The Condenser is so adjusted as to concentrate the rays of light about 2 mm above its surface, which is the average thickness of the microscopic slides, under an angle equal to the angular aperture of the highest power objective, which is about 120°.
In the lower power objectives the angular aperture is to be reduced by the iris diaphragm.
To focus the Condenser properly it is adjustable by rack and pinion movement on Stands A, I, Ia, Ib, and by side screw on Stands II and IIa.
4. The body of the microscope carries the tube and is fitted with two adjustments for focussing; a coarse adjustment and a fine adjustment. The smooth working of these adjustments is one of the chief requirements of a good microscope.
The coarse adjustment consists of rack and pinion and moves the tube of the microscope in a vertical groove with the least possible friction. The teeth of the rack and pinion are set obliquely to the axis of the tube and are so adjusted that two teeth of each are always interlocked, thus avoiding all possibility of slipping or loss of motion in the movement.Figure of the Micrometer-screw of the fine adjustment.
The fine adjustment consists of a micrometer screw which moves the tube and arm of the microscope supporting the coarse adjustment vertically upon a triangular column. This column is virtually a continuation upward of the upright support of the base of the microscope. Around the column is a broad collar so accurately fitted that it moves smoothly upon it with a minimum of friction and still without lateral motion, the movement being controlled by means of a micrometer screw at the top of the column. The head of this micrometer screw, a section of which is shown in the accompanying figure, is milled and is graduated in such a way as to indicate the exact degree of motion of the microscope tube which is accomplished by turning the micrometer screw, each division of the graduation corresponding to a motion of the tube through 1/100 millimeter, and a complete revolution of the screw corresponding to a motion of the tube through ½ millimeter. The accuracy of this adjustment and the smoothness of its motion must be conceded to be a triumph of mechanical skill.
Stands A. and I. are fitted with a new fine adjustment device (one division on the micrometer screw corresponding to 1/1000 mm.) which is fully described on pages 25-26.
5. The tube of the microscope encloses a second tube, or draw-tube, which latter carries the eye-piece, and is so graduated as to indicate the exact length of tube in use at any time. The lower end of the tube has a thread into which the various objectives or a nose-piece screw. Tube and objectives are provided with the so-called "Society screw".
The nose-piece has now become an almost indispensable part of a working microscope. It can, however, be used to best advantage only on such stands as are provided with a coarse adjustment by rack and pinion. Aside from the advantage derived from the rapid changing of objectives, which it permits, it is so accurately made and centered as to materially facilitate the focussing of the various objectives. It is only necessary to focus with the fine adjustment to obtain a view of the same microscope field which had been under observation before the change was made.
As it is necessary for this purpose that the objectives should be accurately adjusted to the nose-piece, it is very desirable that in ordering an instrument its nose-piece should be ordered at the same time if one is to be used, as subsequent ordering may necessitate the return of the stand and objectives to us.
Stands A, I, Ia, Ib, II, IIa, IIb and III are those which are best suited to fine microscopical investigations. Among them the physician and bacteriologist will find an instrument entirely suited to his particular needs.
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