REPORT OF NATIONAL MUSEUM, 1922. 113 



insoluble in proportion to the amount of light allowed to strike it 

 through the negative, and after slight treatment is ready to receive 

 the printer's ink. A print from it gives all the tones and values of 

 the original. Very accurate results are obtained, as the grain is very 

 fine, and in color work where three or four plates are used is but 

 slightly perceptible even under a magnifying glass. The plate has 

 to be damped before it is inked, as in lithography, and is printed 

 on a hand or power press as desired. The results obtained depend 

 largely upon the quality of the negative. The retouching of the 

 negative is the expensive part of the process, but when this is com- 

 pleted, the rest is mechanical. Burnishing, scraping, reetching, or 

 retouching enter into the photomechanical processes, none of which 

 are automatic, as the name might imply. 



The entire collotype series has been rearranged and brought up 

 to the standard of the other photomechanical exhibits through the 

 courtesy of the above-mentioned firms. Of historical importance 

 are the first prints to come to this country in 1866, made by Tessie 

 du Motay, and numerous other specimens showing the work done 

 in the last 50 years. 



The other new accessions of importance will be mentioned in re- 

 lation to the rearrangement to which a large part of the year has 

 been devoted. This plan brought like specimens, both technical and 

 historical, together for convenient study. 



Photogravure was the first subject undertaken. The historical 

 exhibit contains specimens covering almost a hundred years, from 

 1826 to 1922. The Museum fortunately owns a print from the 

 original plate, which was the first recorded success of engraving by 

 the aid of light, made in 1826 by Joseph Nicephore Niepce. Fox 

 Talbot and Paul Pretsch are well represented by their Avork done 

 in the early fifties; one of Pretsch's original plates is included. 

 There is an example by Mante, 1853, one by Niepce de St. Victor, 

 1856, and others. The original screen and a print, submitted by 

 Gen. Frederick von Egloffstein in his patent application in 1865, 

 covering the first successful screen process, are in this exhibit. There 

 are many representative examples from 1870 down to the present, 

 all fairly uniform in quality. A few fine examples are printed in 

 color at one impression. Rotagravure work from 1894 to date is 

 shown. 



At the beginning of this year the halftone exhibit was deficient 

 in the work of foreign countries. Upon request, several English 

 firms supplied examples of their work. John Swain & Sons (Ltd.) 

 and the Half Tone Engraving Co. (Ltd.), both of London, con- 

 tributed about 25 specimens. The English Avork is quiet and ar- 

 tistic, while the American work is apt to be more brilliant. This is 

 17075—22 8 



