334 H. L, Smith on a Finger for the Microscope. 
tubes g and A by means of the head 7, and so adjust by slipping 
the tube g up and down, and by moving the arm mo, or the 
forceps p, in the socket r, that the end of the hair shall stand 
just over and a trifle above the dot; now clamp g by means of the 
screw f; and bring the point of the hair so that it may be seen, 
slightly out of focus, when looking into the microscope, just 
over the intersection of the cross, or the dot, by means of the 
screw s. The whole may now be elevated by means of the rack 
of the microscope and the adjusting slide replaced by another 
containing the material from which it is desired to pick up cer- 
tain objects. If the material is dried upon mica from a suspen- 
sion in alcohol, the object may be picked up easily; if dried 
, from suspension in water, it sometimes adheres 
strongly, but with a little care is easily detached. If the illumin- 
ation from below is too strong, the hair, which is, of eourse, a 
little within the proper focus, is not so readily seen at the same 
time with the object as it is with a feebler illumination. Upon 
ame this care must be taken to avoid a current of air, made 
by t 
