Microscopy. 
MICROSCOPY. 
Thoma's Camera Lucid a. ^ — The ( 
well adapted for a low magnifying power (1-6), nor is any all( 
ance made in their construction for the refractive index of 
the drawing-paper r 
of vision. 
In the construction of Thoma's camera the above difficulties 
are avoided, and it is specially recommended for drawing with a 
magnifying power of from 1-10 times, and for the production of 
reduced drmvings. 
camera consists of a blackened, metallic frame containing 
from 0.15 to 
silvered mirror. Both 
thickness, while the other (c) 
ors are parallel with each other i 
clined at an angle of 45° to the 
in order to draw an object magnified four times, we place at o 
a convex eye-glass with a focal distance of 40 cm., and then fasten 
the camera upon the vertical rod so that the distance b c &ndc 2 = 40 
w' ^'l'!''^ ^"^' ^' ^' Wliittmaii, Director of the Lake Laboratory, Mil- 
' Zeitschrift f. wiss. Mikroskopie, v. S, p. ^97, Sept., 1887. 
