On Microscopes in General. 1 



While describing the different kinds of microscope, 

 a few words should be said on the binocular micro- 

 scope, and the solar and oxy -hydrogen microscopes. 



The binocular microscope (No. 2) is an ingenious 

 application of the principle of the stereoscope to the 

 compound microscope. Some objects are extremely 

 well suited to this mode of observation, and some 

 details which appear confused and unmeaning when 

 viewed with only one eye, appear to assume form and 

 solidity in the binocular instrument. 



The solar microscope is pronounced in an excel- 

 lent article, published more than twenty years ago in 

 the " Penny Cyclopaedia," to be nearly superseded 

 by the oxy-hydrogen instrument. The principle is 

 the same in both ; the rays from the sun or from the 

 brilliant artificial light are thrown on the object, and 

 then through a kind of simple microscope to a large 



names were originally given to convey an idea of the performance 

 of the compound microscope, as compared with that of the 

 simple (see Quekett on the Microscope, chap, ii.) It may be 

 useful to state the powers of each of the object-glasses with the 

 lowest eye-piece of the microscope used in this work. It will give a 

 general idea of the powers of object-glasses, but as these vary 

 slightly in each microscope, the purchaser of an instrument should 

 always obtain a table of its powers. 



Lowest eye-glass and two-inch object-glass 20 diameters. 



Ditto, and one-inch object-glass 60 



Ditto, and halt-inch object-glass 100 



Ditto, and quarter-inch object-glass 200 



Ditto, and one-eighth of an inch object-glass ... 420 



The expression "diameters " will be found explained at page 31. 

 The two other eye-glasses supply intermediate powers, and the follow- 

 ing higher powers, 670,900. 



