192 THE MICROSCOPE Dec 



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Photo-Micrography. — The art of photographing the image 

 of a microscopic object, which image has been enlarged by the 

 microscope, is called photo-micrography, in contradistinction 

 to the art of producing microscopic photographs of large objects, 

 winch require the aid of a microscope to render the details visi- 

 ble. Dr. J. W. Draper, of New York, is supposed to have been 

 the first to take photo-micrographs by the daguerreotype 

 process, as he was the first to take portraits by this method, 

 since which time thousands have probably practiced this art, 

 abroad and at home. In this country Draper, Rood, Fowler, 

 Deames, Rutherford, Seller, Mercer and Col. Woodward, Drs. 

 Curtis and Sternberg, of the army, stand prominent as masters 

 of photo-micrography. The object of photo-micrography is to 

 produce a faithful photograph of the enlarged image of a micro- 

 scopic object, which shall not only show everything apart from 

 color, that we can see in the microscope, but even more, as it is 

 the most reliable and easy way of making faithful records of 

 the appearances and measurements of microscopic objects. Be it 

 for illustrations of scientific books or for lantern slides for lec- 

 tures, or for supplying evidence in law courts in cases of adul- 

 teration, forgery, murder, etc., its importance is obvious. In 

 the domain of botany, biology, physiology, pathology, bacteri- 

 ology, chemistry, petrology, etc., and in fact, wherever the 

 microscope is used, there photo-micrography is destined to be- 

 come daily of more service and importance. The method of 

 taking a photo-micrograph consists chiefly in the following 

 operations. Focussing and illuminating the object in much the 

 same way as for visual examination at the eye-piece end of the 

 microscope, with the camera ; focussing on the ground gla^^s ; 

 replacing the latter by the holder containing the sensitive plate 

 and making the exposure and finall} developing the negative. 

 To command success in photo-micrography requires not only 

 the possession of a good microscopical apparatus and camera, 

 but also an intimate acquaintance with the principles of micro- 

 scopical illumination for photography, which depends for cor- 

 rectness first of all upon the choice of the illuminator, and 

 secondly, upon the condenser and that of the objective, the 

 rule being that the aperture of the condenser ought to be the 

 same as that of the objective if we wish to obtain critical 

 images. 



