78. The rapid improvements which have taken place in the printing press during the last twenty years, afford another instance of saving in the materials consumed, which has been well ascertained by measurement, and is interesting from its connection with literature. In the old method of inking type, by large hemispherical balls stuffed and covered with leather, the printer, after taking a small portion of ink from the ink-block, was continually rolling the balls in various directions against each other, in order that a thin layer of ink might be uniformly spread over their surface. This he again transferred to the type by a kind of rolling action. In such a process, even admitting considerable skill in the operator, it could not fail to happen that a large quantity of ink should get near the edges of the balls, which, not being transferred to the type, became hard and useless, and was taken off in the form of a thick black crust. Another inconvenience also arose--the quantity of ink spread on the block not being regulated by measure, and the number and direction of the transits of the inking-balls over each other depending on the will of the operator, and being consequently irregular, it was impossible to place on the type a uniform layer of ink, of the quantity exactly sufficient for the impression. The introduction of cylindrical rollers of an elastic substance, formed by the mixture of glue and treacle, superseded the inking-balls, and produced considerable saving in the consumption of ink: but the most perfect economy was only to be produced by mechanism. When printing-presses, moved by the power of steam, were introduced, the action of these rollers was found to be well adapted to their performance; and a reservoir of ink was formed, from which a roller regularly abstracted a small quantity at each impression. From three to five other rollers spread this portion uniformly over a slab (by most ingenious contrivances varied in almost each kind of press), and another travelling roller, having fed itself on the slab, passed and repassed over the type just before it gave the impression to the paper.