Messrs. Donkin and Bacon had for some years previous to this date been
busily engaged with printing machines, and had indeed, in 1813, obtained
a patent for an apparatus, in which the types were placed upon the sides
of a revolving prism; the ink was applied by a roller, which rose and
fell with the eccentricities of the prismatic surface, and the sheet was
wrapped upon another prism fashioned so as to coincide with the
eccentricities of the type prism. One such machine was erected for the
University of Cambridge. (See _fig._ 917.) It was a beautiful specimen
of ingenious contrivance and good workmanship. Though it was found to be
too complicated for common operatives, and defective in the mechanism of
the inking process; yet it exhibited for the first time the elastic
inking rollers, composed of glue combined with treacle, which alone
constitute one of the finest inventions of modern typography. In König’s
machine the rollers were of metal covered with leather, and never
answered their purpose very well.
Before proceeding further, I may state that the above elastic
composition, which resembles caoutchouc not a little, but is not so
firm, is made by dissolving with heat, in two pounds of ordinary
treacle, one pound of good glue, previously soaked during a night in
cold water.
[Illustration: 918