Page:The Story of the House of Cassell (book).djvu/145

 Mr. Edward Evans, had supplied a little colour work, but this required the engraving of a separate wood block for each printing, and it was only, therefore, a very partial solution of the difficulty.

Next a method was devised whereby it was possible, by the introduction of screens of coloured glass between the object to be photographed and the negative, to photograph the colour value of the three primary colours separately. Blocks were then made by the ordinary half-tone process from each of the negatives, and, these blocks being printed one over the other, in yellow, red, and blue, a combination is produced which very well represents the colour of the original. The method was invented by Dr. Vogel, in Germany—or, rather, it was patented by Dr. Vogel, but, unfortunately for the patent, it had been described previously in an English journal by Mr. Ives, a well-known American worker in process. The making of colour blocks was eagerly taken up in America, and it was a certain specimen of American work which stimulated effort in the same direction on this side. Mr. Bale still has a copy of that print, and well remembers showing it to Farlow Wilson, the printing manager. It was stated to be the result of three printings on a flat bed machine, and it was as full in colour as a lithograph of fifteen to twenty printings. It seemed to be the death-knell of lithography, though lithographers, not believing that such an effect had been obtained by means so simple, scoffed. They were wrong. At the same time the problem was not yet solved in England. True, it was now possible to make colour blocks, and very good ones, but it was not easy to get good results from them. The English block-maker made the blocks, but the English printer could not print them. Accurate "register" to prevent overlapping of colour was indispensable, and English machines were not rigid enough to give this accuracy. For some time the results were so poor that several firms which experimented with the prints abandoned the effort as impracticable. At this point Mr. Bale made up his mind to go to America