370 Tue Microscope. 
the former being moved by the action of the lever. This stage, 
if well made, could not be unqualifiedly condemned, although 
it had some glaringly objectionable features. 
For special studies special stages are made. Warm stages are 
used, the warmth being produced by heated air, electricity, hot 
water or by heated metal plates. Some complicated arrange- 
ments are described which are often interesting and amusing, 
for at times it would seem as if the inventors of these queer de- 
vices put down on paper what they think ought to be useful, if 
somebody could make them successful. They have dial plates 
attached, and thermometers, and spirit lamps, and electric bat- 
teries, and steam cylinders, and boilers with a multiplicity of 
rubber tubes, all of which, with many others for cooling objects, 
for subjecting them to the influence of gases, and for other pur- 
poses, are doubtless more or less useful in their particular de- 
partments, but they need not detain us now, as the beginner will 
not need them,‘nor the advanced microscopist, either, I imagine. 
One of the most delightful of microscopical luxuries, one 
which in some cases is an absolute necessity, is a mechanical 
stage, provided it is of the right kind. The beginner will prob- 
ably not buy a stand with a mechanical stage, though he might 
do worse things, but if he should even once perform any serious 
work with that device, he will, I am sure, never abandon it 
voluntarily. A mechanical stage is a “thing of beauty” and if 
well made, the rest of that hackneyed quotation is descriptive of 
it. But whatis it? Only a stage so made that the horizontal 
and the vertical motions are accomplished by rank and pinion. 
The description is short, it seems a small matter, but the stage is 
one of the most important parts of the stand. An inconvenient 
stage means an inconvenient stand. If properly constructed, a 
mechanical stage is strong, light, firm, durable, desirable and 
unrelinquishable. If improperly made it may be strong, firm, 
thin and light, it will be altogether abominable. Scarcely any 
part of the stand sees so much active service as the stage, unless 
it is the fine adjustment, and scarcely any part must approach 
perfection so closely as the stage unless, again, it is the fine ad- 
justment mechanism. To have that part loose and wabbling, 
with the image dancing at every turn of the screw, is as bad 
as having lost motion in the racks and pinions of the mechani- 
cal stage, or to have the parts loose and rattling, or to have them 
