511 



NOTES. 



THE ROUSSELET COMPRESSOR. 



By E. M. Nelson, F.R.M.S. 

 {Read March 2mh, 1912.) 



Although my microscopical work is mostly concerned with 

 mounted objects, yet living and other specimens which happen 

 to come in my way are often examined, for which purpose the 

 Rousselet compressor is invaluable. There are two small faults 

 to be found w-ith this compressor; but as both may easily be 

 remedied they do not much matter. 



The first is that when my rotating (double) nose-piece is put 

 into action, unless the microscope body is first racked up by the 

 coarse adjustment the front lens of the objective, which it is 

 intended to use, comes into contact with the edge of the milled 

 head at the top of the screw-post. This trouble is got rid of by 

 lengthening the arm which holds the cover ; the post is then out 

 of the way. 



The second trouble affects me probably more than other micro- 

 scopists. If my cover-glass gets broken or uncemented from the 

 ring, what is to be done ? I have no means of cutting a new 

 one, and no cement by which to fix it. The only thing is to 

 post it to town to have it repaired ! Those who mount slides 

 have cover-glasses, cements, balsam, spirit-lamps, etc., always at 

 hand, and are unable to appreciate the difliculty such a simple 

 case as this presents. They say, " Why not get a bottle of 

 cement and a few covers, and then you can repair your com- 

 pressor ? " This is very true ; but as there is no occasion to use 

 either the cement or the cover-glasses more than once in several 

 years, they get lost or the cement dries up, so when wanted it 



