302 THE MICROSCOPE. 
lens, and supply a means for its manipulation. Figure 2 is a 
low power, non-adjustable objective. Every maker has his own 
special pattern for the brass mounting of his objectives, but all 
objectives of all opticians have the same general form, differing 
only in detail and in size, the screw end of course being the same 
in all, so that it may fit the screw on the lower end of the body 
tube. 
In figure 3 is shown, about natural size, the lower end only of 
the body and arm from the cheap stand with a French Triplet 
lens in position. Here the reader may easily observe the dif- 
ference in the appearance 
of the French Triplets and 
of the good objectives, 
figures 1 and 2. In figure 
3 notice how the lower 
end of the body suddenly 
narrows into a conical 
form, in order to receive 
the narrow screw of the 
French lenses. In praise- 
worthy stands there is no 
such appearance. In them 
the end of the body is 
terminated by an opening 
three-fourths of an inch 
in diameter. Notice also 
that the screw thread of 
the body is on the outside, 
while that of the lens is 
on the inside, whereas Fig.3. 
on commendable and) useful stands, and on good objectives the 
reverse is the arrangement, the screw thread being on the out- 
side of the objective, and on the inside of the body tube. The 
intending purchaser of a microscope will do well to reject any 
stand and all objectives with screws as just described and as 
shown in figure 3, as such lenses are the objectionable French 
Triplets and stands specially prepared for them, the whole being 
in the language again of our English friends, “cheap but nasty.” 
French ‘lriplets are intended to be used in two ways, either 
with the three parts united, a combination which is bad enough 
