Microscopes and Accessory Apparatus Part 8

36. =Horizontal Microscope.= This instrument consists of a microscope tube placed horizontally on a long extensible column, supported in turn by a tripod base provided with levelling screws and a round spirit level.

The extension of the upright supporting column is accomplished by two sliding motions, the lower, controlled by a set screw only, being intended for coa.r.s.er adjustments, the upper, controlled by rack and pinion, for finer adjustments. A millimeter scale and a vernier serve to indicate the degrees of the various motions, so that vertical motion of the microscope tube to the extent of 1/10 mm may be accomplished.

The microscope tube carries a spirit level and revolves upon a horizontal disc. The objective, consisting of two separable doublets, permits three degrees of magnification of 5, 9 and 48 cm focal distance respectively. A rack and pinion adjustment serves as adjustment of the microscope tube. A micrometer, 1 cm long and divided into 100, in the diaphragm of the ocular still further increases the availability of the instrument for making fine and accurate measurements.

The instrument serves as a useful aid in many physical and physiological investigations.

Price, including objective, ocular and micrometer =40.--=

=Microscopes for Mineralogical Research.=

We construct two Microscopes for mineralogical investigations. Both are adapted for determining the axes of elasticity and for the differentiation of isotropic and anisotropic bodies. Stand I alone is adapted for determining the optical axes and their angles.

Only such objectives, condensers and oculars are available for mineralogical examinations as have been shown after careful examination in polarized light to be free from polarization.

[Ill.u.s.tration: Mineralogical Stand I.]

=Mineralogical Stand I.=

37. This microscope corresponds in its dimensions to Stand Ia as described on page 31. Coa.r.s.e adjustment by rack and pinion, fine adjustment by micrometer-screw, the milled head of which has 50 divisions, each representing a motion of the objective of 1/100 mm. The condenser, iris-diaphragm and polarizer can be raised and lowered by rack and pinion. A triple condenser facilitates the observation of the axial lines in the microscope. It is so arranged as to be easily replaced by a simple diaphragm-carrier. By means of a collar attached to the end of the tube the objective is brought into coincidence with the centre of the revolving stage.

This revolving stage is divided into 360 degrees and fitted with a vernier and index. Two scales on the stage, at right angles to each other, permit accurate location of specimens. The Nicol prism, which serves as a polarizer, can, after turning the iris-diaphragm aside, be drawn out from under the latter. The zero position of the Nicol prism is indicated by a line, as well as the angles 90, 180, 270. The a.n.a.lyser is mounted in metal and is firmly fixed above the eye- piece. The a.n.a.lyser rotates on a disc graduated to 360 deg. The front of the tube has a movable window which provides access to the inner tube. In the latter is an opening for the introduction of a Bertrand lens. This lens serves the purpose of magnifying the interference figures produced by the converging rays of polarized light. This lens and the eye-piece can be raised or lowered by rack and pinion. In the a.n.a.lyzer is a slide for the insertion of gypsum and quartz plates at an angle of 45 degrees.

In many investigations it is advisable to employ an a.n.a.lyzer introduced laterally into the tube, instead of the one mentioned above.

The following parts are supplied to complete the outfit: Triple nose-piece.

Eye-piece 0, with Bertrand's quartered quartz plate.

Eye-piece I with cross-lines, Brezina's Calcspath-plate, cleft perpendicularly to its axis, made to fit over eye-piece I, Klein's gypsum and quartz plates for insertion in the opening over the objective.

Price of the stand with these accessories =160.--=

38. =The same= with eye-piece III, objectives 1, 3, 5, 7.

1/12 Oil-Immersion, magnifications 18-800 =236.--=

The new mechanical stage No. 98 (See page 78) can be fitted to the stand for the purpose of investigating large preparations and serial sections.

Price =28.--=

[Ill.u.s.tration: Mineralogical Stand II.]

=Mineralogical Stand II.=

39. The base and pillar are in one piece, neatly j.a.panned black. The coa.r.s.e adjustment is by rack and pinion.

The stage is revolving and graduated on the edge into 360 degrees. A pointer indicates its position.

The polarizer has stop at zeropoint and also marks at 90, 180 and 270. It is held in a spring-sleeve and the substage can be raised and lowered by lateral screw, or may be swung to one side. The condenser is mounted in separate arm above the polarizer and swings out of the optical axis by means of a lever, if parallel instead of convergent rays are desired.

The a.n.a.lyzer fits into an opening of the tube above the objectives and can be instantly thrown in or out of the optical axis. There is a slot below the a.n.a.lyzer for the insertion of quartz and gypsum plates.

By means of a collar with two centering screws attached to the end of the tube, the objective may be brought into the optical axis.

Price of this microscope with eye-piece I with cross-lines, Klein's quartz wedge and gypsum plate, red, I. order =$56.--=

40. =The same= with eye-piece III. and objectives 3 and 5.

Magnifications 60-250 =74.--=

=Dissecting Microscopes and Hand Lenses.=

[Ill.u.s.tration: Large Dissecting Microscope No. 41.]

41. =Large Dissecting Microscope.=

Stand on heavy horse-shoe base, large stage with gla.s.s plate, adjustment by rack and pinion. The lens-carrier is movable for examining large plates. Illumination by movable plane mirror and white gla.s.s plate. Metal hand- rests covered with leather may be attached to the sides of the stage. They fit inside the mahogany case.

A black metal plate with wheel-diaphragm or a milk- gla.s.s-plate can be inserted below the stage, serving as dark or white back-ground respectively.

Stand without lenses in mahogany case =16.--=

42. =The same= with three aplanatic lenses after Steinheil, magnifying 8, 16 and 20 diameters =28.--=

43. =The same= with these lenses and Abbe's drawing apparatus =40.--=

44. =The same stand= with prism-tube No. 49 for erected image. Objectives 1*, 2, 3, magnifying 18, 40 and 80 diam. =47.25=

[Ill.u.s.tration: Simple Dissecting Microscope No. 45.]

45. =Simple Dissecting Microscope=, with adjustment by rack and pinion, movable plane mirror and white gla.s.s plate, gla.s.s stage in metal frame. Metal hand-rests covered with leather fit inside the case. Stand without lenses =8.--=

46. =The same= with two aplanatic lenses after Steinheil, Magnification 10 and 20 diam. =16.--=

47. =The same stand= with prism-tube No. 49, for erected image; with objectives 2 and 3, magnifying 40 and 80 diam. =36.--=

[Ill.u.s.tration: Dissecting microscope with erected image after R.

Pfeiffer.]

=The Dissecting microscope with erected image according to Prof. R.