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 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 ovsr 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. 



