34 
ELEMENTARY CHEMICAL MICROSCOPY 
place, as shown in Fig. lo. Accompanying the instrument is a 
rheostat so constructed as to permit the lamp to be connected 
with ordinary house¬ 
lighting circuits. One 
of the great advantages 
of this illuminating 
device is the rapidity 
with which it can be 
attached or removed 
from the microscope. 
The radiant being self- 
contained there is no 
loss of time or annoy¬ 
ance of properly “ lin¬ 
ing up ” the source of 
light. 
The Silverman Illu- 
^ c-i Til • ^ u j minator may also be 
Fig. io. The Silverman Illuminator attached to _ 
the Objective of the Microscope. USed with micrOSCOpes 
of the Greenough dou¬ 
ble objective type. For this purpose a clamp, Fig. ii, is pro¬ 
vided which fastens to the stage of the microscope. The fingers 
are held back by a ring R, attached to the spindle of the clamp; 
there is thus afforded an unobstructed view through the central 
orifice. The lamp and mounting are adjusted below the objective 
so as to interfere in no way with the field of view. Unless the 
worker is left handed the clamp should be fastened on the left side 
of the stage and as far back toward the pillar as possible so as not 
to interfere with manipulations which may be made upon the 
stage. 
The character of the light rays thrown by the Silverman 
Illuminator is similar to those reflected by the old time para¬ 
boloid save that they more nearly axial, in other words the 
light effect is that of a combination of both axial and oblique 
rays streaming from an incandescent filament in the form of 
a semicircle. This will be readily understood by referring to 
Fig. 12. The dotted lines a, a' mark the points of attachment 
