2 AQUATIC MICROSCOPY FOR BEGINNERS. 



but one glass, and the distance from the object much 

 shorter when in focus. In the compound microscope 

 the lenses near the eye magnify the image formed by 

 the lower lenses, and that image is inverted and tran- 

 sposed, the upper side of the object then appearing to 

 be the lower, the right-hand side the left, and the left- 

 hand the right. In the simple microscope, however, 

 these changes do not take place; and in those forms 

 where two or three lenses are combined, the effect is 

 the same as though one glass of great magnifying 

 power were used. But separate the lenses so that the 

 upper shall magnify the image produced by the lower, 

 and you will have a simple form of compound micro- 

 scope. With the simple microscope we see the object 

 itself; in the compound we see the, enlarged image of 

 the object. 



As a simple microscope does not seem to invert and 

 reverse the object, and because the distance between 

 the two is long when the low-power glass is in focus — 

 that is, when the lens is in such a position that the 

 magnified object looks clear and distinct to the eye — 

 it is always used for the examination of a flower, the 

 surface of a piece of bark, a stone, an insect, or any 

 other specimen of considerable size, or one fhat is vis- 

 ible to the naked eye, more, extended study being re- 

 served for the compound instrument at home. A sim- 

 ple microscope, a "pocket-lens" as it is often and pref- 

 erably called {J^ig. i), is ■ indispensable to every one 

 that has a taste for nature studies, arid a desire to 

 know somewhat of the beauties hidden from our un- 

 aided vision; for the simplest glass shows the' student 

 unimagined charm in the petal of a flower, in the sand 

 we walk.-, on, and in the green scum that floats upon 



