Note 187 — Chapter XIV · Financial Difficulties—Boulton in Cornwall—Attack and Defence of the Engine Patent.

Some of the specimens in water colour are to be seen at the Museum of Patents, South Kensington. When the paper is moistened with the finger, the colour easily rubs off. The whole subject of these pictures has recently been thoroughly sifted by M. P. W. Boulton, Esq., in his ‘Remarks on some Evidence recently communicated to the Photographic Society’ (Bradbury and Evans, 1864), apropos of the Papers of Mr. W. P. Smith on the same subject, in which it was surmised that they were the result of some photographic process. Mr. Boulton clearly shows, from the original correspondence, that the process was mechanical colour-printing. He also adds,—“From the brief statements which I remember to have heard from my father concerning the polygraphic process, my impression of it was that it copied colour mechanically, not merely chiaro-scuro. And I agree with the opinion which has been expressed to other persons, that in the coloured specimens in the Museum, there are indications that the colour was laid on mechanically,—not by hand or brush.” As the process of “dead-colouring” the pictures is occasionally referred to, it is probable that the pictures passed through more stages than one, as in the case of modern colour-printing. In one of Eginton’s letters, three plates were spoken of as necessary for taking impressions of one of the pictures.