382 THE Microscope. 
tives which are made for short tubes as well adapted to them as 
the long tube objectives are adapted to the long tubes?” If a 
short tube objective will not bear the extension to the standard 
length, will a long tube objective bear any better the enormous 
extension of a long draw-tube in addition to the standard length? 
My own tube is short, and vastly more convenient than a longer 
one, particularly if it is ever to be used in a vertical position. My 
objectives were made for that particular kind of stand, with the 
exception of a Bausch & Lomb one-eighth. I am anxious to 
know if I am working at such a terrible disadvantage. 
Yours truly, 
Boston, Mass. GuIDON. 
Eprror Tue Microscorr :— 
I regret that I have not yet made my meaning plain. It is 
just this. An objective corrected for a short tube may be an 
excellent objective for that tube, but it will not be a good objec- 
tive if used on a long tube; and an objective corrected for a long 
tube may be a good one when used on a long tube, but it will 
not be a good one when used on the standard body lengthened 
to the full extent of the draw-tube. If “Guidon” is employing 
objectives on a short tube which were made for short tubes, 
what more does he want? He is certainly not working to a dis- 
advantage. And since the Bausch & Lomb one-eighth is an ad- 
justable glass, he may be able to make the corrections needed to 
adapt it to use on the short tube, but I doubt if he gets the best 
results from that excellent objective. If short bodies are to be 
used, then select objectives made especially for short tubes; if 
long tubes are to be employed, then take those objectives which 
have been made for the long bodied instruments, and even then 
do not detract from a good image by enormously lengthening 
the draw-tube. Yours truly, 
An AMATEUR. 
Eprtror THe Microscorpr:— 
The statement of “Amateur” that to put the fine adjustment 
upon the nose piece, is to put it in an objectionable place, I do 
not think is the experience of the majority, for this reason. The 
fine adjustment placed upon the back of the arm necessitates an 
arrangement whereby it supports the weight of the whole body, 
«nd also the weight of all the mechanism of the coarse adjust- 
