THE MICROSCOPE AND ITS PARTS. 15 



he should use what is called in the trade, Japanese 

 filter-paper, a soft, light, vegetable product from 

 Japan, much employed by dentists, in some of their 

 work, and almost as extensively by advanced micros- 

 copists for drying the fronts of immersion-lenses, or 

 those objectives which are used with a drop of water, 

 of oil, or of some chemical solution between them and 

 the cover-glass over the object. The paper can be 

 bought from the dealers in microscopical supplies. A 

 piece once used should be thrown away. 



When the objective is to to be taken from its box, 

 unscrew the cover and tip the lens into the palm of 

 the left-hand, supporting it with the fingers; pick it 

 up with the thumb and finger of the right-hand against 

 the sides of the tube or brass mounting, and it will be 

 ready, when reversed, to be screwed to the stand. If 

 it is not to be returned to the box immediately after 

 use, as will often happen if the student has more than 

 one, and he desires to examine the object with an- 

 other power, stand it on its screw-end on the table, 

 and to protect it from dust invert its box over it. The 

 latter can be lifted off in a moment, and the objective 

 will then be ready to be picked up as before. 



What objectives should the beginner select? If 

 possible, . he should have ■ two, a. low-power and a 

 moderately high magnifying power. If unable to pur- 

 chase both at once, let him by all means first take 

 what is called the one-inch objective; if he, can also 

 buy a high-power, the :t or | will be the proper glass. 

 But for this he can wait. There is so much to be ex- 

 amined with the one-inch objective, or even by the two- 

 inch, tha!t, for a.long time, he will scarcely feel the 

 need of 6'thers. The one-inch, if p'roperly selected. 



