CHAPTER XIV. 



MISCELLANEOUS HINTS TO MIC B SO P I S T S. 



. 



ON CLEANING THE GLASSES. " When you clean the eye- 

 glasses (a point of great importance to pure vision), do not 

 remove more than one at a time, and be sure to replace it be- 

 fore you begin another ; by this means you will be sure to 

 preserve the component glasses in their proper places ; recol- 

 lect that if they become intermingled, they will be useless. 

 Keep a piece of well-dusted chamois leather, slightly impreg- 

 nated with some of the finest putty or crocus powder, in a little 

 box to wipe them with for it is of consequence to preserve it 

 from dust and damp ; the former will scratch the glasses, and 

 the latter will prevent you from wiping them clean. As to the 

 object-glasses, endeavor to keep them as clean as possible 

 without wiping, and merely use a camel's-hair pencil to brush 

 them with ; for wiping them hard with anything has always a 

 tendency to destroy their adjustment, unless they are firmly 

 burnished into their cells." Dr. Goring. 



ON STOPPING FALSE LIGHT IN MICROSCOPES. This is one 

 of the most important requisites in an instrument; for however 

 perfect it may be, if there is the least light reflected from the 

 mountings of the glasses, or within the tubes, the fog and glare 

 produced will materially deteriorate their performance ; it is 

 therefore necessary that all their surfaces be made as sombre as 

 possible. The usual method of effecting this is to cover the 

 parts while hot with a black lacquer, made by mixing lamp- 



