204 HOW TO SEE WITH THE MICROSCOPE. 



and the stage level there will be found, in ninety-live 

 cases out of the hundred no necessity for covering the 

 mount. I simply place on a clean glass slide a drop of 

 the specimen to be examined and, without covering it at 

 all, place the same on the stage, the spring clips being 

 turned back out of the way, for even these are a draw- 

 back to rapid work. It will be often necessary to use 

 re-agents, and to this end the long working distance 

 affords every facility. With this two-thirds or the inch I 

 am enabled, by eye-piecing, to get nice definition up, say 

 to 200 or 250 diameters. Here we have a practical ad- 

 vantage arising from the use of a high -angled glass, and 

 one of the greatest value. In thus being able to dispense 

 with the use of covers a wonderful saving of time is 

 accomplished; the objective, too, is far enough out of 

 the way, so that it does iiot become clouded by the 

 evaporation, nor injured by the fumes of the re-agents. 

 Any desirable change in amplification that can ordina- 

 rily occur is furnished instantly by changing the eye- 

 piece. And here let me say that the oculars should slip 

 in and out of the tube just as easily as possible without 

 decentering the object viewed. A tight fitting eye-piece 

 is an abomination of the first order; any ocular of mine 

 will drop out of the tube instantly by tipping the stand 

 " upside down." Now the advantage of the short tube 

 is this : You are enabled to work over a table of the 

 ordinary height, and to view your object comfortably, 

 at the same time the table forms a very acceptable rest 

 for the forearm ; on the other hand, by keeping the tube 

 its standard length one must use a lower table, and the 



