THE MIcRoscOoPE. ; pA 
to supply it. The American Society of Microscopists suggests 
that eye-pieces be one and one-fourth inches in diameter, which 
of course means a body-tube slightly larger. One English firm 
makes eye-pieces one and one-fourth, one and five-eighths and 
one and seven-eighths inches in diameter, with body-tubes of 
corresponding sizes. Why a single size only should not be 
made, the firm alone knows. The diameter of the tube on my 
own stand, from a prominent American maker, is one and eight- 
twentieths inches, or only three-twentieths greater than the 
standard recommended by the American Society for eye-pieces, 
yet I doubt if that maker would willingly alter his pattern even 
by so little; and a solid one-half inch eye-piece from Mr. Tolles 
is only one and one-twentieth inches in diameter, demanding a 
wealth of paper wrapped around it to make it usable on my 
stand. This is hardly a valid criticism, however, since the solid 
eye-pieces of all opticians who make them, are expected to be 
supplied with an adapter to fit the body-tube. 
_ The purchaser of a stand should select the one with the widest 
body. There is no objection to the use of an adapter on a small 
eye-piece to make it fit a large tube, nor even to the application 
of a paper bandage for the same purpose, since the microscopist 
can himself apply the latter with a successful issue. If each 
turn of the stout paper band is well coated with mucilage, the 
cylinder thus formed will, when dry, be almost as hard as wood, 
and if injured may be easily reapplied without cost. 
There is already a standard for the length of the body. It is 
ten inches, or the same as the arbitrary standard for normal dis- 
tinct vision. Yet at the present day it would seem that most 
makers do their best to have the body less than the standard 
length. In some instruments it is only one and one-half inches 
less, the proper length being obtained by pulling out the draw- 
tube. It is true that the short tubes are used on the continental 
stands, and on those modelled after them, and there they are 
necessary, since the pillar has no joint for inclination, the mic- 
roscopist being forced to use the instrment in a vertical position. 
If human necks and backs were made of India rubber, then 
those microscopists who use and recommend stands with short 
bodies, might join the majority of working microscopists and 
elongate their necks over the standard tubes in a vertical position. 
But since human vertebre are not elastic, this class of micro- 
