ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
417 
nected by stiff joints, which cause the lamp to remain in any position 
in which it has been placed, and the possible positions of elevation or of 
obliquity are such as to give light in any manner desired. 
The oil-tank can be rotated in the holder, thus turning the edge or 
the broadside of the flame towards the Microscope, as necessity may 
require. The thick glass chimney 
as well as the flame is concealed 
by the metallic hood, well black- 
ened, while a projection on the side 
of the hood directs the rays of 
light towards the bull’s-eye. The 
latter, of unusual size (3 in. diam.), 
is supported by an independent 
support. The advantage of this is 
that the entire illuminating appa- 
ratus may be disconnected from 
the bull’s-eye, or the light directed 
otherwise than through the bull's- 
eye if more general illumination 
is desired. The light from the 
flame is passed through a ground 
glass or blue glass at pleasure, and 
before reaching the bull’s-eye. 
Strong or faint light, direct or 
oblique light, can all be had easily 
and without changing any adjust- 
ment of the Microscope. The 
1/2-in. wick gives a very good 
flame, kerosene being used to burn. 
The arrangements for draught and 
for cleaning are good. 
Some new Improvements applied to the mechanical part of the 
Microscope.* — M. Yves Delage, in collaboration with M. Nachet, has 
devised several improvements in the centering and other mechanical 
arrangements of the Microscope. In their new triple nose-piece or 
revolver the spring-catch consists of a cylindrical roller C (fig. 49), which 
is carried by a powerful spring R attached to the fixed piece of the 
revolver. This spring serves to press the roller into a semi-cylindrical 
groove hollowed in each of the arms of the movable piece. The groove, 
which has a radius a little less than that of the roller, so as to prevent 
all lateral motion, is cut in a small sliding carrier, which is kept pressed 
against a powerful spring by the conical screw-head F. By turning the 
screw the carrier is moved and the point of the movable piece displaced 
until arrested in front of the fixed roller. By this means the transverse 
adjustment is effected. 
For the adjustment from front to back a movement of rotation about 
a horizontal axis is employed. For this purpose the central part of the 
movable piece is formed of strong tempered steel, flexible enough to 
yield beneath the pressure of a screw, but sufficiently rigid not to 
1892. 
Arch. Zool. Exper. et Gen., x. (1892) pp. i.-ix. 
2 G 
