recent Improvements in Printing, 187 



In 1815 I obtained a patent for curving stereotype plates, for 

 the purpose of fixing them on a cylinder. Several of these machines, 

 capable of printing 1000 sheets per hour on both sides, are at 

 work at the present day, and twelve machines on this principle 

 were made for the Bank of England a short time previous to the 

 issue of gold. ( Fig. 6 and 7.) 



It is curious to observe that the same object seems to have 

 occupied the attention of Nicholson, Donkin and Bacon, and my- 

 self, viz. the revolution of the form of types. Nicholson sought to 

 do this by a new kind of type, shaped like the stones of an arch. — 

 Donkin and Bacon sought to do this by fixing types on a revolving 

 prism, and at last it was completely effected by curving a stereotype 

 plate. See Diagram. 



In these machines two paper cylinders are placed side by side, 

 and against each of them is placed a cylinder for holding the 

 plates ; each of these four cylinders is about two feet diameter, — on 

 the surface of the plate cylinder are placed four or five inking rollers, 

 about three inches diameter : they are kept in their position by a 

 frame at each end of the plate cylinder, the spindles of the rollers 

 lying in notches in the frame, thus allowing perfect freedom of 

 motion and requiring no adjustment. 



The frame which supports the inking-rollers, called the waving- 

 frame, is attached by hinges to the general frame of the machine ; and 

 the edge of the plate cylinder is indented, and rubs against the 

 waving-frame, causing it to wave, or vibrate to and fro, and, con- 

 sequently, to carry the inking-rollers with it, thus giving them a 

 motion in the direction of their length, called the end motion. — 

 These rollers distribute the ink upon the three-fourths of the sur- 

 face of the plate cylinder, the other quarter being occupied by the 

 curved stereotype plates. The ink is held in a trough ; it stands 

 parallel to the plate-cylinder, and is formed by a metal roller, re- 

 volving against the edge of a plate of iron; in its revolution, it 

 becomes covered with a thin film of ink; this is conveyed to the 

 plate-cylinder, by an inking roller vibrating between both. On the 

 plate-cylinder, the ink becomes distributed, as before described, and 

 as the plates pass under the inking rollers, they become charged 

 with colour ; as the cylinder continues to revolve, the plates come 

 in contact with a sheet of paper in the first paper cylinder, whence 

 it is carried, by means of tapes, to the second paper cylinder, where 

 it receives an impression on its opposite side, from the plates on 

 the second plate cylinder, and thus the sheet is perfected. 



These machines are only applicable to stereotype plates, but they 



