CHAPTER XV. 



THE ART OP MAKING PHOTO-MICROGRAPHS. 



PHOTO-MICROGRAPH is the picture of a 

 microscopic preparation, as seen by the eye 

 when enlarged by means of the microscope ; 

 its converse, being a much-reduced image of an object 

 photographed on glass, which is called a micro-photograph, 

 and which can only be seen when placed in the microscope. 

 This latter, however, is a mere curiosity, and, although 

 it excites some wonder when looked at, has no educational 

 or scientific value, except perhaps as a proof of the fine 

 structure of a photographic film. A photo-micrograph, on 

 the other hand, affords a valuable means of displaying to a 

 large audience the delicate structure of various organisms, 

 both animal and vegetable ; besides which that of coal and 

 other minerals can: be well exhibited. Lantern micro- 

 scopes, some of very beautiful construction, have been 

 brought forward from time to time, and one of them, at 

 least, I shall refer to in a subsequent chapter. 



But although lantern microscopes may give very fine 

 results, it is an indisputable fact that the amount of light 

 which is able to get through the tiny aperture of a high- 

 power objective, is small. And when this small amount 



p 2 



