CH. V/fZ.] PHOTO-MICROGRAPHY. 209 



and some pure white. With good printing the fine half tone work on 

 the larger natural history specimens is capable of giving very satisfac- 

 tory results as may be seen by observing Fig. 160 and 161. 



For the methods of Photo-Micrography and Photography in general, consult the 

 works mentioned in the bibliography. Especial attention is also called to the 

 papers of Woodward " On an improved method of photographing histological 

 preparations by sunlight, 1871, and on the Application of Photography to Mi- 

 crometry." 



To the papers and discussions of A. C. Mercer in the various volumes of the 

 Proceedings of the American Microscopial Society. 



To the papers and discussions on photo-micrography by Piffard ; Journal of the 

 Royal Micr. Soc. 1892, and 1893, also in the Amer. Jour. Med. Sciences 1893. The 

 paper by Dr. G. A. Piersol, — "Some experiences in Photo-Micrography " in the 

 American Annual of Photography for 1890 will also be found very instructive and 

 helpful. In ever}' volume, and freqeuntly in every number, of the microscopical 

 journals of this and foreign countries one may find articles, notes or references to 

 work in photo-microgaphy. Excellent papers are also frequently found in the 

 photographic journals and annuals. 



Thomas J. Wray. — Photo-Micrography by use of ordinary objectives, practically 

 considered with specimens of work. Proc. Amer. Micr. Soc. Vol. XVIII, (1896). 

 The specimens in connection with this paper impressed one that simple apparatus 

 was no bar to success. 



Sunlight and Heliostat. — In case one wishes to utilize sunlight for Photo- 

 Micrography it would be of great advantage to consult the papers of Woodward 

 mentioned above and also the paper of Mercer in the Jour. Roy. Micr. Soc, 1892, 

 pp. 305 to 318. For work with sunlight, a heliostat is almost a necessity. An ex- 

 cellent and inexpensive form was devised by Dr. L,. Deck and described and 

 figured in the Proc. Amer. Micr. Soc, 1891, pp. 49-50. A good form of heliostat 

 is also figured and described in Van Heurck, pp. 265-266. 



Sunlight is not so easily managed as some form of artificial 'light, even when 

 one possesses a heliostat. 



For samples of photo-micrographic w T ork, see the magnificent photo prints ex- 

 hibited by Dr. Woodward at the Centennial Celebration at Philadelphia in 1876, 

 the works of Mason, Sternberg, Piersol, Wilson and Starr; Carpenter-Dallinger, 

 Pringle, Bousfield Nehauss, etc., besides the great embryological and morpho- 

 logical journals where photo-micrographic plates are frequently published. 

 Catalogs of photo-micrographic apparatus, in some cases, have admirable speci- 

 mens of photo-micrographs. 



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