Page:On the economy of machinery and manufactures - Babbage - 1846.djvu/99

From Wikisource
Jump to navigation Jump to search
This page has been proofread, but needs to be validated.
ECONOMY OF MATERIALS.
65

no such sheet is used, but a blanket is employed as its substitute; this does not require changing above once in five thousand impressions, and instances have occurred of its remaining sufficiently clean for twenty thousand. Here, then, is a proof that the quantity of superfluous ink put upon the paper in machine-printing is so small, that, if multiplied by five thousand, and in some instances even by twenty thousand, it is only sufficient to render useless a single piece of clean cloth.[1]

The following were the results of an accurate experiment upon the effect of the process just described, made at one of the largest printing establishments in the metropolis.[2]—Two hundred reams of paper were printed off, the old method of inking with balls being employed; two hundred reams of the same paper, and for the same book, were then printed off in the presses which inked their own type. The consumption of ink by the machine was to that by the balls as four to nine, or rather less than one-half.

  1. In the very best kind of printing, it is necessary, in the old method, to change the set-off sheet once in twelve times. In printing the same kind of work by machinery, the blanket is changed once in 2000.
  2. This experiment was made at the establishment of Mr. Clowes, in Stamford-street.