528 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
mechanical stage, but a most desirable substitute for usual work with 
the Microscope ; permitting, as it does, absolute freedom of movements 
about a field for full two inches horizontally and one inch vertically, 
thus allowing ample room for even serial sections ; and possessing, as it 
does, exquisitely smooth sliding movements, over the stage proper of the 
Microscope, of almost absolute precision. My carriage and stage, made 
for me a year ago by Zentmayer of Philadelphia, after my own specifica- 
tions, is of such excellent workmanship as to give perfectly level and 
precise movements under a power of 2250 diameters (Zeiss 1/12 homo, 
immers., 18 compens. ocular). 
The drawing shows in fig. 63 a plan of the sliding carriage, and in 
fig. 64 a cross-section on a vertical central line. The stage should have 
Fig. 63. Fig. 64. 
two flat rails, one on each side of its aperture, slightly raised above the 
surrounding surface, on which the carriage slides ; and the stage may be 
square or round in shape, as preferred. The outlines of the carriage are 
shown by the full lines of the figures. Affixed to the bottom of the 
carriage are glass rails, A and B, of which the outlines and positions are 
indicated by dotted lines. These glass rails of the carriage slide on and 
over the metal rails of the stage. The circles a a and b show respectively 
knobs for holdfasts and a centering stop for object slide C, indicated by the 
broken lines of the figures. A spring clip c is provided, which can be 
swung against the upper side of the slide, as indicated by the dotted 
lines in fig. 63, to hold it securely in place when the stage is perpen- 
dicular or while it is rotated, or swung aside out of the way as shown 
by full lines. The slide rests with sufficient security against the ledge 
of the carriage when the stage is level or inclined, free from being 
clipped in a rigid position, justly criticized as objectionable by Dr. 
Dallinger. The carriage is kept in contact on the rails of the stage by 
the spring and ivory-pointed thumb-screw D, and the pressure thereby 
regulated. It will be observed that there is ample room in the opening 
of the sliding carriage, above the object-slides, to insert the end of the 
forefinger in quick focusing as recommended by Dr. Dallinger and 
practised by many microscopists ; and also that the object-slide is not 
slipped in a rigid position, but can be when desired. This opening also 
permits the use of wide angle, short focus or immersion substage con- 
