CH. VIII] PHOTO-MICROGRAPHY 221 



were made by Wedgewood and Davy, and Davy says : "I have found that images 

 of small objects produced by means of the solar microscope may be copied without 

 difficulty on prepared paper. "f 



Thus among the very first of the experiments in photography the microscope 

 was called into requisition. And naturally, plants and motionless objects were 

 photographed in the beginnings of the art when the time of exposure required 

 was very great. 



At the present time photography is used to an almost inconceivable degree in 

 all the arts and sciences and in pure art. Even astronomy finds it of the greatest 

 assistance. 



It has also accomplished marvels in the production of colored plates for book 

 illustrations, especially in natural history. For an example see Comstock's Insect 

 Life, 2d edition. 



Although first in the field, Photo-Micrography has been least successful of 

 the branches of photography. This is due to several causes. In the first place, 

 microscopic objectives have been naturally constructed to give the clearest image 

 to the eye, that is the visual image as it is sometimes called, is for microscopic ob- 

 servation, of prime importance. The actinic or photographic image, on the other 

 hand, is of prime importance for photography. For the majority of microscopic 

 objects transmitted light ( \ 64) must be used, not reflected light as in ordinary vis- 

 ion. Finally, from the shortness of focus and the smallness of the lenses, the 

 proper illumination of the object is accomplished with some difficulty, and the 

 fact of the lack of sharpness over the whole field with any but the lower powers, 

 have combined to make photo-micrography less successful than ordinary macro- 

 photography. So tireless, however, have been the efforts of those who believed in 

 the ultimate success of photo-micrography, that now the ordinary achromatic ob- 

 jectives with ortho-chromatic or isochromatic plates and a color screen or petrol- 

 eum light give good results, while the apochromatic objectives with projection 

 oculars give excellent results, even in hands not especially skilled. The problem 

 of illumination has also been solved by the construction of achromatic and apoch- 

 romatic condensers and by the electric and other powerful lights now available. 

 There still remains the difficulty of transmitted light and of so preparing the 

 object that structural details stand out with sufficient clearness to make a picture 

 which approaches in definiteness the drawing of a skilled artist. 



The writer would advise all who wish to undertake photo-micrography seri- 

 ously, to study samples of the best work that has been produced. Among those 

 who showed the possibilities of photo-micrographs was Col. Woodward of the U. 



tin a most interesting paper by A. C. Mercer on "The Indebtedness of Pho- 

 tography to Microscopy," Photographic Times Almanac, 1887, it is shown that : "To 

 briefly recapitulate, photography is apparently somew 7 hat indebted to microscopy 

 for the first fleeting pictures of Wedgewood and Davy [1802], the first methods of 

 producing permanent paper prints [Reede, 1 837-1 839], the first offering of prints 

 for sale, the first plates engraved after photographs for the purpose of book illus- 

 tration [Donne &Foucalt, 1845], the photographic use of collodion [Archer & Dia- 

 mond, 1851], and finally, wholly indebted for the origin of the gelatino-bromide 

 process, greatest achievement of them all [Dr. R. L. Maddox, 1871]. See further 

 for the history of Photo-micrography, Neuhauss, also Bousfield. 



