HALFTONE SCREEN — KAINEN 415 



It is necessary here to omit mention of some transitional workers, 

 none of whom had particuLarly original ideas, and to proceed to 

 Edward and James Bullock of England, who patented a process in 

 1866 which was put to use in producing halftones in photolithography. 

 The Bullocks' specifications stated : 



Our process is to reticulate tlie negatives, which may be done by placing the 

 copy of a reticulated or granulated surface face to face with any ordinary 

 negative, and copying both together through the light, thus producing a trans- 

 parency from which a negative must be taken, a print from which upon paper 

 prepared by any of the bichromate and ink processes known in the trade will 

 have the reticulated or granulated appearance aforementioned. This copy with 

 the reticulations may be transferred to a stone or zinc plate, and any number of 

 impressions may be printed off, each bearing the markings or reticulations of 

 the interposed copy with the lights and shades according to the original negative, 

 and bearing all the appearance of an engraving or lithograph. 



Varying this process, the Bullocks described the use of a transfer 

 paper, either ordinary or photographic paper, which was coated with 

 a gelatinous solution : 



Upon the paper so prepared is printed a granulated or reticulated pattern of 

 any character, composed of dots or lines of ink of any kind or colour having the 

 power partially or completely, according to requirements, of preventing the 

 light acting on the paper beneath. In this case the specks of ink themselves 

 form a medium, and by their aid excessive contrasts are avoided and half tones 

 secured. Such picture when so obtained is passed to a lithographic stone or 

 zinc plate, and a printed proof produced therefrom . . . 



During the latter part of the 1860's most experimenters were gen- 

 erally acquainted with the halftone screen, realized its possibilities, 

 and attempted to perfect it as a mechanical instrument. The first 

 worker to produce good practical results was William A. Leggo, of 

 Canada, who, with George E. Desbarats, patented a process in 1871 

 which incorporated the use of a screen in contact with a negative. 

 Before this period, however, Leggo and Desbarats had patented in 

 1865 a sort of improved Pretsch method of relief halftone, which they 

 called Leggotype, through the use of a single-line screen and the 

 swelled-gelatin process. Later, this process was the basis for the 

 commercially successful Moss process. 



Leggo, who was the laboratory worker while Desbarats was the 

 financial backer, made cross-lined screens through darkened collodion 

 coatings on glass plates. By the use of these screens they made the 

 first halftone reproductions to be printed in any periodical. The 

 first, a portrait of H. E. H. Prince Arthur, appeared in the Canadian 

 Illustrated News for October 30, 1869, and was printed by lithography. 

 In 1873 Leggo and Desbarats founded the New York Daily Graphic, 

 which became the first daily newspaper in the United States to use 

 illustrations in the modern sense — in other words, the first daily 

 periodical in this country to use photomechanical halftone illustra- 



