44 HOW TO SEE WITH THE MICROSCOPE. 



maker. It would probably take me a trifle longer to 

 adjust nicely an objective on the Histological, and but a 

 trifle ; while, on the other hand, all the objections con- 

 nected with the adjustment at the nose-piece are 

 avoided. 



The Histological, as furnished by the maker, has 

 simply a plain stage with spring-clips. This defect did 

 not pass unnoticed by the writer, Mr. Zentmayer re- 

 sponding promptly to his request with the improvised 

 stage described on a preceding page. 



It remains to be noticed that the Histological has 

 neither rack nor pinion,* and that the coarse adjustment 

 is effected by sliding the body within an adjustable 

 "jacket." There is no novelty in this, for the sliding 

 tube is " as old as the hills," and has been extensively 

 adopted in the construction of cheap stands. 



The author felt very much like kicking at this feature 

 of the Histological. In a little time, however, experi- 

 ence taught him that the sacrifice of the rack and pinion 

 was not such a serious matter as might be supposed. 

 The sliding movement of the 1 body tube within its 

 jacket in the little stand is very smooth, regular, and 

 reliable, while, on the other hand, there are some ad- 

 vantages accruing to the slide that are not to be ob- 

 tained by the use of the rack and pinion. 



For example: suppose we are working over wet 

 preparations, and unfortunately the front of the objec- 

 tive becomes immersed in the liquid a misfortune 



*Mr. Zentmayer now furnishes the Histological, with or without the 

 rack and pinion coarse adjustment. AUTHOR. 



