MICROSCOPY. 61 
Fig. 43 is a large view of one of the screws, with its indicator. 
The indicator may be a simple pin set in the wooden frame, but 
is more convenient if made movable around the axis of the 
screws, so that when the razor is returned after sharpening they 
may be all turned around to the 0 of their respective screws and 
therefore all read alike while the successive cuts are being made. 
On the side of the indicators are scales which show how many com- 
plete revolutions of the screws have been made. These indicators 
should move quite stiffly, so as not to be accidentally misplaced 
when turning the screw heads. 
With the hands upon the triangle and the eye at the microscope 
tube, the razor can be moved so that its edge shall either make a 
drawing cut or push straight through the object like a chisel, ac- 
Fig. 42. Fig. 43. 
cording as either method or any gradation between them suits best 
the nature of the substance cut. Thus perfectly even slices can 
be cut, and it is quite easy to take them in consecutive order even 
when called off in the midst of the work and compelled to wait 
half an hour before resuming it. It is a luxury to take off slice 
after slice and know that there is no danger of losing just the 
slices you want especially to see. The object is kept wet with 
glycerine, and just as the razor begins to cut, a drop of glycerine 
is pl on its edge in which the slice floats without sticking ; 
though care must be taken in the case of very thin and small sec- 
tions not to lose them in a large drop of glycerine in which they 
would be found with great difficulty. By this method slices gobo 
of an inch in thickness, or rather in thinness, can be all worked 
out nicely, though before it was adopted such thin slices were all 
