PHOTO-MICROGRAPHS. 
INTRODUCTION. 
PHOTO-MICROGRAPHS are sun-pictures of micro- 
scopic objects more or less magnified. 
A MICRO-PHOTOGRAPH is a microscopic picture 
of an object which can be seen by the naked 
eye. 
These two names should not be confounded, as 
they are required to distinguish two very different 
things. By means of photo-micrographs, those 
unfamiliar with the use of the microscope may be 
made acquainted with a variety of beautiful and in- 
teresting objects which are completely beyond the 
reach of ordinary vision ; while micro-photographs 
are simply curiosities in the art of photography, 
and are to be viewed under the microscope. 
The art of making photo-micrographs is of re- 
cent origin, and in no part of the world has more 
been done to perfect the technique of this art, than 
in our own country. The foremost place among 
those who have aided in this progress will readily 
be conceded to Lieutenant-Colonel J. J. Woodward, 
a distinguished surgeon in the United States Army, 
whose photographs of difficult test-diatoms and of 
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