96.  Calico printing from blocks.  This is a mode of copying, by surface printing, from the ends of small pieces of copper wire, of various forms, fixed into a block of wood.  They are all of one uniform height, about the eighth part of an inch above the surface of the wood, and are arranged by the maker into any required pattern.  If the block be placed upon a piece of fine woollen cloth, on which ink of any colour has been uniformly spread, the projecting copper wires receive a portion, which they give up when applied to the calico to be printed.  By the former method of printing on calico, only one colour could be used; but by this plan, after the flower of a rose, for example, has been printed with one set of blocks, the leaves may be printed of another colour by a different set.

97.  Printing oilcloth.  After the canvas, which forms the basis of oilcloth, has been covered with paint of one uniform tint, the remainder of the processes which it passes through, are a series of copyings by surface printing, from patterns formed upon wooden blocks very similar to those employed by the calico printer.  Each colour requiring a distinct set of blocks, those oilcloths with the greatest variety of colours are most expensive.

There are several other varieties of printing which we shall briefly notice as arts of copying; which, although not strictly surface printing, yet are more allied to it than that from copperplates.

98.  Letter copying.  In one of the modes of performing this process, a sheet of very thin paper is damped, and placed upon the writing to be copied.  The two papers are then passed through a rolling press, and a portion of the ink from one paper is transferred to the other.  The writing is, of course, reversed by this process; but the paper to which it is transferred being thin, the characters are seen through it on the other side, in their proper position.  Another common mode of copying letters is by placing a sheet of paper covered on both sides with a substance prepared from lamp-black, between a sheet of thin paper and the paper on which the letter to be despatched is to be written.  If the upper or thin sheet be written upon with any hard pointed substance, the word written with this style will be impressed from the black paper upon both those adjoining it.  The translucency of the upper sheet, which is retained by the writer, is in this instance necessary to render legible the writing which is on the back of the paper.  Both these arts are very limited in their extent, the former affording two or three, the latter from two to perhaps ten or fifteen copies at the same time.

99.  Printing on china.  This is an art of copying which is carried to a very great extent.  As the surfaces to which the impression is to be conveyed are often curved, and sometimes even fluted, the ink, or paint, is first transferred from the copper to some flexible substance, such as paper, or an elastic compound of glue and treacle.  It is almost immediately conveyed from this to the unbaked biscuit, to which it more readily adheres.