Part 4

59. =Demonstration lens-holder=, consisting of a hardrubber stage with handle, clamps for holding the preparation in position, and with a moveable lens- holder. Without lens =2.40=

60. =Focussing lens= for photographic camera. Lens in spring-sleeve with clamping ring =4.75=

61. =Handle= with ring for holding lens =1.25=

The =aplanatic triplets after Steinheil= are remarkable for their large, flat field and excellent definition, free from chromatic aberration.

Diameter Visual field Magnification

62. 24 mm 20 mm 8 diam. =4.--=

63. 15 " 15 " 10 " =4.--=

64. 12 " 12 " 12 " =4.--=

65. 10 " 10 " 16 " =4.--=

66. 6 " 3,5 " 20 " =4.--=

67. 5 " 2 " 30 " =4.--=

68. 3 " 1 " 40 " =4.--=

The =achromatic doublets= have a very large, clear and flat field.

69. 30 mm 35 mm 5 diam. =4.--=

70. 23 " 20 " 8 " =3.25=

=Doublet magnifier=, consisting of two double convex lenses.

71. 23 mm 25 mm 6 diam. =1.25=

The doublet No. 69 can only be used as a hand lens. The mounting of all the other lenses is such that they fit any of the dissecting stands or lens holders. Aplanatic triplets 64-68 can only be used on stands with rack and pinion adjustment.

72. The aplanatic lenses Nos. 62-66 are also to be had with a moveable cover and ring adapting them for use as pocket lenses.

Price, when thus mounted =4.75=

73. =The Binocular Preparation Microscope=, after the model of Eilhard Schulze permits the convenient use of both eyes in dissecting small anatomical and botanical preparations. It consists of two Brücke lenses, adjusted to an accurate focus.

Both tubes are moveable on a joint and are adjustable to various distances between the observers eyes. The distance of the eye from the preparation is about 250 millimetres; the field of vision is large and flat; the magnification, four diameters; lenses are adjustable to either vertical or horizontal position and may be raised and lowered on the vertical support, thumb-screws fixing them in the desired position. A rack and pinion serves as fine adjustment =24.--=

74. =Greenough's Stereoscopic Binocular Microscope.= Two microscope tubes are so arranged as to bring the same object into focus in the axis of each tube, the tubes being set at an angle to each other for this purpose. The stand is provided with rack and pinion adjustment and both draw-tubes are also regulated by a rack and pinion arrangement, so that they may be adapted to the correct distance of the observers eyes.

By interposition of prisms the image is rendered erect. Magnification, 20 diam. Price =80.--=

74a. =Corneal-Microscope=, is designed for the examination of the interior of the eye.

=Prismtube= No. 49 with eye-piece =16.--=

=Objective= of low power permitting 2 degrees of magnification =6.--=

=Stand= on heavy base, with rack and pinion adjustment etc. =8.--= ------- =30.--=

=Apparatus for Blood Examinations.=

75. =The Micro-Spectroscope= fits into the tube of the microscope like any ordinary eye-piece and may be fixed in any desired position by means of the thumb-screw M. The position of the bright and dark lines of the spectrum and their respective wave lengths are ascertained by means of a scale. The flat drum A, the interior of which is shown in section, contains the slit and the comparison prism. The slit is regulated by the screws F and H. The lever T moves the comparison prism across one half of the slit. The cylinder Q above the eye-piece contains the Amici prism. At the point N of the horizontal tube RN is the micrometer scale, illuminated by the mirror O. After raising the spring- catch L the upper part of the spectroscope may be turned round the pivot K, thus allowing of the adjustment of the eye-piece =66.--=

(A full description accompanies each instrument.)

76. =Hand-Spectroscope=, Browning's, for spectroscopic examination of the blood =12.--=

76a. =Hand-Spectroscope= with comparison prism, mirror, and holder for vials =16.--=

77. =Thoma's Haemacytometer= consists of an object glass with carefully constructed cell, a ground absolutely plane coverglass and two pipettes for mixing the blood and saline solution used in the examinations. One of these pipettes, for estimating the number of red corpuscles is so graduated as to permit dilution of the blood 100 or 200 times as required; the other, for counting the white corpuscles (leucocytes), is graduated for dilution of the blood 10 or 20 times.

The volume contents of the pipettes are most carefully determined and the depth of the cell is established by accurate micrometric measurement, thus permitting very exact observations by means of this instrument.

(A full description with each instrument) =14.50=

78. =Mixing-Pipette for white corpuscles= =3.60=

79. =Mixing-Pipette for red corpuscles= =3.60=

80. =Thoma counting chamber, with coverglass= =5.75=

81. =Türck counting chamber with coverglass= =7.25=

82. =Ehrlich's Eye-piece= is provided with a diaphragm having a square opening, the size of which is regulated by a small lever.

This eye-piece is designed to facilitate the estimation of the relative numbers of red and white blood corpuscles in dry preparations.

Full directions accompany each instrument =12.--=

82a. =Apparatus= for the clinical determination of the alcalinity of the blood, after Prof. C. S. Engel.

The following parts compose the apparatus:

1) a capillary pipette so graduated as to permit the dilution of 0,05 cc. blood from the finger, up to 5 cc. with distilled water.

2) a beaker, for the reception of the diluted blood.

3) a burette mounted on stand, capacity 10 cc. Full directions accompany each outfit. Price in box =8.--=

=Micrometers.=

83. =Screw-micrometer eye-piece= for accurate measurement of large objects. Between the eye lens and the collecting lens of a Huyghenian ocular there is a millimeter scale etched on glass, above which is a moveable indicator whose position is controlled by a micrometer screw to which a graduated drum is attached. The value of each graduation on the drum (about 1/20 of the micrometer value of the objective) must be determined for each combination of ocular and objective by means of the stage micrometer. The eye lens of the ocular is moveable to permit accurate focus upon the scale. The apparatus slips into the tube of the microscope like any ordinary eye-piece and is fixed in position by a thumb-screw at the side =20.--=

84. =Micrometer eye-piece.= The mount unscrews in the centre to permit the introduction of the micrometer scale. The eye lens is moveable to permit of accurate focus on the scale =4.--=

85. =Glass-Micrometer for the eye-piece=, to drop on the diaphragm of the eye-piece. Scale of 5 mm divided into 100 parts =2.50=

86. =The same=, 10 mm divided into 100 parts =2.--=

87. =Stage-Micrometer=, 1 mm divided into 100 parts etched on glass =3.75=

88. =Stage-Micrometer=, photographed on glass, 2 mm divided into 200 parts =1.40=

89. =Eye-piece Micrometer=, divided into squares for counting scattered objects in the field. Mounted. Distance between the lines 0,5 mm =2.--=

90. =Glass slide with cell= 2/10 mm deep, with ocular micrometer No. 89, in box =3.25=

91. =Glass slide with cell= the floor of which is divided into squares, 1/400 square mm each, in box =4.--=

=Drawing Apparatus.=

The two following =drawing eye-pieces= Nos. 92 and 93, have quickly found favor among those having frequent occasion to make drawings from microscopic preparations and are now largely used in educational institutions as an aid to students in the study of their specimens. In both eye-pieces the prism is so adjusted as to accomplish total reflection of the image, thus doing away with loss of light and with secondary reflections, such disturbing features of those forms of drawing apparatus of which a mirror forms an essential part.

92. This =drawing eye-piece= is employed with the stand in the vertical position. The reflected image lies at the side of the microscope, the rays passing off at an acute angle from the reflecting prism near the top of the eye-piece. The eye-piece slips into the tube of the microscope like any ordinary eye-piece and is held in position by a thumb-screw. The drawing field is at once visible without further adjustment, and the picture is clear and sharp. The brightness of the drawing field may be regulated by smoked glass plates mounted in two moveable metal arms =8.--=

93. This =drawing eye-piece= is similar in construction to that just described, but is so arranged as to throw the image vertically downwards behind the microscope when the latter is inclined at an angle of 45 degrees. In this case also the picture reflected is clear and sharp, devoid of all disturbing secondary images. As the image is reflected vertically downwards upon the table, no special drawing stand is necessary as there is no distortion of the picture. The intensity of the light may be modified by smoked glass plates mounted in two moveable metal arms =10.--=

For a description of these drawing eye-pieces and of the principles involved in their construction reference may be had to the Zeitschrift für wissenschaftliche Mikroskopie, XII, 1895.

94. In =Abbe's Drawing Apparatus= the drawing field is reflected by a mirror at the side of the instrument and by a prism which fits over the eye-piece of the microscope. The prism is supported on a vertical hinge so that it may be readily turned out of the axis of the microscope without disconnecting the whole apparatus from the stand. It is shown turned to the side in the figure. A cylindrical cap accompanies the apparatus which fits over the prism holder and has six lateral windows in which are smoked glasses of various intensity, serving to regulate the lightness of the reflected drawing field =12.--=

The =Drawing boards= serve two purposes. They afford a smooth plane surface for the drawing paper and they are so arranged that they may be inclined at such an angle as to receive the rays of the reflected image at right angle to their surface, thus doing away with any distortion of the image on the paper.

95. This =drawing board= is especially adapted for use with drawing eye-piece No. 92. When in the position indicated in the figure its drawing surface forms an angle of 12° to the horizontal =2.--=

96. In =Giesenhagen's drawing board= the drawing surface may be adjusted at various angles and may be raised and lowered =4.--=

For drawing eye-piece No. 93 and the Abbe drawing apparatus the surface of the drawing board should be horizontal.

97. The =drawing apparatus= after v. Tubeuf serves for drawing objects from nature. By means of a prism mounted in a metal box, the object is reflected into the eye in such a manner that its image appears erected on the drawing surface. This is quite an advantage when drawing from nature but is unimportant when using a drawing apparatus on the microscope. Two smoked glasses mounted in moveable metal arms serve to moderate the intensity of the light. On the side of the prism nearest the eye is a small wheel diaphragm attached to regulate the size of the opening. The apparatus is mounted on a heavy nickel-plated stand with vertical and lateral adjustments controlled by thumb-screws =12.--=

=Mechanical Stages.=

98. =Mechanical stage= adapted to Stands I, Ia and Ib. The stage is readily attached to the microscope by means of a small screw, _C_, which screws into a thread in the microscope just behind its stage, and binds the mechanical stage firmly in position and always in the same position. It may be again removed by simply unscrewing this set screw.

The movements of the stage are at right angles to one another, are accomplished by carefully constructed rack and pinion adjustments and the exact position of each adjustment is indicated by vernier scales. The extent of the lateral movement is 50 mm; that of the other 30 mm.

This stage permits the careful and systematic examination of large specimens and its construction is so perfect that by means of the vernier scales the most minute objects may be readily replaced in the field of vision, even after removal and readjustment of the stage, provided only that their location when in the field of vision as indicated by the scales had been noted =28.--=

99. =Large mechanical stage= for stand, _A_, adapted for slides 50×100 mm; both movements by rack and pinion adjustments =32.--=

100. =Mechanical Stage No. 100.= When a mechanical stage is ordered subsequently to a microscope outfit and under such circumstances that its correct adjustment to the stand by a skillful mechanic is impossible we advise the purchase of this more readily adjusted mechanical stage, which may readily be attached to Stands I, Ia, Ib, IIa and IIb by means of a thumb-screw. It is as carefully constructed as Mechanical Stage No. 98 and serves the same purpose in every particular =28.--=

100a. =New Mechanical stage=, simplified form =20.--=

101. =Warm stage= after Schultze. This consists of a metal stage to which long lateral arms are attached, through which the heat from one or more small lamps is conducted to the central part of the stage and the object. The apparatus is also provided with a condenser, which affords illumination sufficient for the use of high power objectives, and with a thermometer indicating the exact temperature of the centre of the stage, which may be carried as high as 100° C. =12.--=

102. =Warm stage= after Pfeiffer. It consists of a glass chamber through which warm water may be made to flow. A small cell is ground in its surface thus permitting its use as a moist chamber =6.--=

103. =Warm stage= after Stricker. This stage consists of a metal chamber, through which warm water is made to flow when in use, and is provided also with a condenser and thermometer. It may be screwed firmly to any of the square microscope stages =14.--=

104. =Warm stage= after Errera, permitting rapid changes from low to high temperature and vice-versa.

It includes 2 vessels for cold and hot water, mounted on tripods, with rubber-tubing etc. =24.--=

=Photo-micrographic Apparatus.=

The method of employing this apparatus and the general technique of photo-micrography are treated of in a separate pamphlet containing also four photo-micrographs taken with this apparatus.

This little work is furnished with each apparatus.

105. =The Photo-micrographic Apparatus= consists of a heavy iron foot supporting a stout column in which another iron support moves vertically. This latter holds the camera and may be firmly fixed at any height by means of a thumb-screw. This permits the accurate adjustment of the camera to microscope stands of various sizes. The length of the camera is also adjustable by means of a thumb-screw sliding in the upright support. Regulation of the field of the camera is accomplished by a revolving disc diaphragm with openings of five different sizes situated in the neck of the camera. Two simple plate-holders for plates 9×12 and 13×18 cm are supplied with each camera, as are also a ground glass plate and clear glass plate in the frame of the camera serve to catch the picture in the plane of the photographic plate, and a simple lens aids in obtaining a correct focus of the image. A white glass plate, mounted on a stand is of use in diffusing direct sunlight so as to make it available for photographic purposes, and three discs of yellow, blue and green glass are provided which may be inserted over the iris- diaphragm of the condenser when colored light is required.

It is of great advantage to interpose an illuminating lens between the source of light and the mirror, thereby condensing the light-rays, giving a uniform illumination and preventing the heating up of the entire stand, which is a disturbing factor in retaining the focus. The illuminating lens also serves to lessen the time of exposure.

This photo-micrographic apparatus is also available when it is desired to photograph gross specimens as, for example, embryos, insects, etc., by reflected light, as is represented in the figure on p. 86. The photographic objective of 64 mm focal distance, is best adapted to this purpose. It fits in a collar in the neck of the camera and yields a magnified image of about 3 diameters. The object is brought into proper focus by means of a small stand, the table of which may be raised or lowered as required.

Price of the apparatus without microscope stand =40.--=

106. =Small stand for supporting specimens= to be photographed by reflected light as mentioned above =4.75=

107. =Welsbach lamp= with reflector =6.--=

108. =Illuminating lens= of 100 mm diam. on stand =12.--=

109. =Photo-micrographic apparatus=, for use in horizontal and vertical position. It is in construction similar to the foregoing, but is provided with joint for inclination and clamping lever, and can be used at any angle.

Large size bellows and plateholder, for plates up to 24×24 cm. Moveable platform with three leveling screws and clamping-bar for holding stand. Price of the apparatus, with 2 simple plate-holders, ground and plain glass plate, etc., without microscope stand =60.--=

=Edinger's Projection Apparatus.=

110. =Edinger's Projection Apparatus=--For projecting and drawing large objects slightly magnified. (Cf. Zeitschrift für wissensch. Mikroskopie. VIII. 1891.)

A polished wooden base, in which a lime wood drawing tablet is inlaid, supports a wooden stand which in turn holds a horizontal metal tube in which are a collecting lens and a reflecting mirror. The upright also carries, two arms, by rack and pinion adjustment, the one supporting the object stage, the other regulating the length of the camera. On the other side of the upright is a support for a lamp. The rays of this lamp are converged by the collecting lens upon the mirror, are reflected downward to the object and through the objective to the drawing board below. The various adjustments permit considerable variation of magnification with the same objective.

Price, including lamp =18.--=

For photographic purposes this same apparatus may be had with Nieser's photographic camera, plate holders, focussing plate etc.

111. =Edinger's Projection Apparatus with Camera= for plates 9×12 cm and 13×18 cm =38.--=

112. =Larger Projection Apparatus with Camera= for plates 9×12, 13×18, 18×24 and 24×30 cm =56.--=

The following Objectives of 24, 35, 42 and 64 mm focal distance respectively may be used in connection with this apparatus for photographic purposes.

113. } { of 24 mm focal distance =18.--= 114. } =Photographic Objectives { " 35 " " " =18.--= 115. } with Iris diaphragms= { " 42 " " " =18.--= 116. } { " 64 " " " =20.--=

The following table shows the size of the preparation which may be resolved by each one of these objectives and the magnification with the smaller and with the larger Edinger Projection Apparatus.