268 PROJECTION OF HORIZONTAL OBJECTS [Ch. IX
Projection of Horizontal Objects
§ 397. As with the magic lantern, so with the projection micro¬
scope some objects must be left in a horizontal position for projec¬
tion. This requires that the microscope be in a vertical position.
As the light source is for giving light in a horizontal direction
(fig. i21), it is necessary to use a mirror or prism to reflect the
horizontal light upward through the vertical microscope and then
another mirror or prism above the microscope to reflect the vertical
light horizontally to the screen. This is shown in fig. 147, 175.
The ordinary mirror of the microscope serves very well for mak¬
ing the light vertical, but for reflecting it horizontally to the screen
a prism or a plane mirror silvered on the face is best, as it gives a
single image, not a double image as would the ordinary glass mirror
silvered on the back.
§ 398. Avoidance of stray light with a vertical microscope.—
This is easily accomplished by using a vertical piece of blackened
cardboard just beyond the microscope as shown in fig. 147. If
light escapes from the sides one can use pieces of black cardboard
or asbestos to enclose the microscope more completely. Ordi¬
narily, however, the single black shield beyond the microscope
will answer.
§ 399. Sample Objects Suitable for Projection with the Differ¬
ent Objectives (see also §3 99a).
Photographic Type of Objectives (Micro-Planars, etc.)
No Tube (fig. 138)
Magnification with:—
Object
Size of Object
Objective
S Meter
Screen
7.5 Meter
Screen
10 Meter
Screen
Brain Section ......
55 to 90 mm.
125 mm.
39
61
80.6
Cerebellum ami Brain
Stem............
50 to 75 mm.
100 mm.
48
74
98.4
Longitudinal Section
of 40 mm. Embryo.
35 to 50 mm.
70 mm.
72
107
143
Section of Eve......
25 to 40 mm.
60 mm.
85
123
I68
Section of Injected
Kidnev ..........
20 to 35 mm.
50 mm.
IOI
147
202
36 Hour Chick Entire
15 to 25 mm.
35 mm.
142
210
285
Transection of Human
Esophagus .......
10 to 20 mm.
30 mm.
167
250
330
Appendix (Homo) . .
5 to 11 mm.
20 mm.
253
370
495