THE MIcROSCOPE. 371 
“lift,” that is to be raised above the general plane surface when- 
eyer the milled heads are turned to bring the mechanism into 
action. Every movement should be smooth, prompt, noiseless. 
Every slightest touch of the milled heads should be followed by 
a movement of the stage plate that shall be visible through the 
microscope, whatever it may be to the naked eye. To be forced 
to turn the milled heads through part of a revolution before the 
pinion engages the teeth of the rack, is something that will un- 
dermine the best disposition the microscopist is blessed with; 
and to feel the pinion crunch against the rack, while the whole 
jolts and bounces along, and lifts the object out of focus, will 
complete the ruin. Nothing of that kind is made in the United 
States, but something very similar is made outside of the United 
States. A perfect mechanical stage reminds me of that human 
being who is low voiced, and gentle, and kind, and good ; whose 
touch is tender, who makes you love him in spite of yourself; a 
rare human being, but precious when found. A perfect me- 
chanical stage is a rarity, but a treasure when discovered. 
The position of the two milled heads actuating the horizontal 
and vertical racks, relegate mechanical stages into two groups, 
one including those with the milled heads projecting beyond the 
margin and parallel with the surface, the other comprising those 
with the milled heads perpendicular to the surface. There is 
little difference in the desirability of either kind, if the milled 
heads are separated from each other, as they often are; but when 
both work on the same axis, as some of them work, then there 
isa choice. Personally, I dislike the stage with the milled heads 
projecting beyond the margin; I greatly prefer the other form, 
where they are on the upper surface, perpendicular to it, and 
working on the same axis. When they are in this first-men- 
tioned position and separated from each other, as they com- 
monly are in this form of stage, using them is, for me at least, 
awkward and inconvenient, cramping the hand and failing to 
supply that rapidity of action so desirable in many inyesti- 
gations, because I am forced to abandon the hold on one screw 
head to seize the other, thus losing time, and often the object as 
well. This is cnly a prejudice, however; the reader may prefer 
a mechanical stage with the milled heads thus arranged. Some 
accomplished microscopists do so. This was the opinion of my 
lamented friend, Dr Allen Y. Moore, of Cleveland, young, brill- 
