MICROSCOPE LAMPS 
165 
a which is attached to the end of the body tube of the micro¬ 
scope. The screws S, S', turned by a small key, permit the 
Fig. ioo. Bausch & Lomb Clutch 
Objective Changer. 
Fig. ioi. Leitz Clutch Objective 
Changer. 
accurate centering of each objective. This is the best type of 
device when centering is essential, but requires a special box for 
holding the objectives to which the blocks h have 
been attached. With the clutch or clamp type 
(Figs. IOO and loi) the ring is of such diameter 
as to permit placing the objectives in their 
usual brass boxes. 
Sedimentation Glasses. — The apparatus illus¬ 
trated in Fig. 103, commonly known as Spaeth’s 
sedimentation glass, will 
be found a most useful 
laboratory device. The 
liquid containing the 
sediment to be examined 
is poured into the glass 
with its stopcock up as 
shown. After subsidence 
has taken place gentle 
stirring will dislodge any 
material clinging to the 
sides of the vessel and this will fall to the bottom. The stop¬ 
cock is now turned a quarter turn and the liquid emptied out. 
The stopcock can now be removed with the sediment contained 
in the conical depression and with but very little of the super- 
Fig. 102. Zeiss Centering 
Objective Changer. 
Fig. 103. Spaeth Sed¬ 
imentation Glass. 
