THE SELECTION AND USE 



OF 



THE MICROSCOPIC. 



What is a Microscope 'I The microscope is an instru- 

 ment which enables us to see either very minute objects or 

 very minute parts of large objects. It is a very popular idea 

 that the name microscope is applicable only to complex instru- 

 ments of considerable power; but this is clearly wrong. A ten 

 cent magnifying glass has as good a right to the name micro- 

 scope as has a complicated binocular instrument with all the 

 latest improvements. By common consent, however, the small 

 hand instruments, without stands, are generally called magni- 

 fiers. An attempt has been made to introduce the foreign word 

 loupe as an equivalent of magnifier. The word loupe is, how- 

 ever, superfluous, and is used only by ostentatious pedants, and 

 by foreigners who are ignorant of English. 



What the Microscope Does. It is well known that 

 the further off any object is, the less it appears. A house at a 

 distance appears less than a man who is close by, and the dis- 

 tinctness with which an object is seen depends largely upon its 

 apparent size. Thus, at a distance, a house not only appears 

 very small, but the windows cannot be distinguished from the 

 rest of the building. As we draw nearer it becomes apparently 

 larger, and the different parts become more distinct. First the 

 windows are seen clearly, then the individual panes of glass, 

 then the bricks, and finally the grains of the material of which 

 the bricks are made. When, however, we approach too closely 

 we again find it impossible to see distinctly, as may easily be 



