The Microscope. 351 



CORRESPONDENCE AND QUERIES. 



To the Editors of the Microscope : 



Gentlemen — I was pleased to note your timely editorial on the 

 use of light in the July issue of The Microscope. The majority of 

 us find it is entirely out of the question to try and make use of 

 natural light (difPused sunlight). We cannot devote the daytime to 

 such work, and, in a smoky city like St. Louis, could not use day- 

 light to an advantage, even if we had the time. I keep two lamps 

 on my work-table. One is a large student lamp that aids me 

 when mounting or preparing specimens. The other is a cheap brass 

 hand-lamp, that serves as a source of light for the examination of 

 objects. When using the latter I turn the flame of the former down, 

 so that its rays will not interfere with the small lamp. Another 

 advantage this summer weather, and not a very small one either, is 

 that the small lamp does not heat up the room. When examining 

 objects I never have more than one light in the room, and above all 

 avoid the flickering flame of a gas jet. 



I fully appreciate the work that our manufacturers are doing in 

 the interest of microscopy, but I do not believe that they should put 

 so much stress upon the value of expensive lamps. Nor could I 

 ever understand why they should charge from five to six dollars for 

 lamps that can be bought in a lamp store for three to four dollars. 



In a new book just received, I notice that the author advises the 

 operator to illuminate the objects surrounding the microscope as 

 brightly as the field is lighted. I believe this is not only a useless 

 precaution, but is also one that will interfere with the proper 

 examination of many objects. 



When it is desirable to use oblique light, the diffused light from 



such an illumination would cause much trouble. I also find that 



when working with the polariscope that but one light should be 



used, and, as far as possible, all the rays concentrated on the 



mirror. 



H. M. WHELPLEY. 



St. Louis, Mo. 



How can I keep the knife of my section cutter bright when not 

 in use ? Despite all my precautions, minute spots of rust appear. 



B. 



Is there a better green for use in double staining wood sections 

 than malachite green? C. 



