Great Facts / A Popular History and Description of the Most Remarkable Inventions During the Present Century

by Frederick C. Bakewell

In the form of printing machines generally used, the types are laid upon an iron table that is moved to and fro by the turning of a wheel connected with a steam engine. The paper is placed upon cylinders covered with flannel, and the impression of the types is produced by the cylinders being fixed so closely to them that, as the table passes backwards and forwards, there is great pressure. The types are inked by a series of rollers, by which the ink is distributed and evenly laid on the face of the types without any manual labour.

The mechanical power gained by an arrangement of this kind arises from the pressure being exerted on a small surface at a time; consequently the power required for producing the impression of the types is not nearly so great as when the whole surface of the types makes the impression at the same instant. The force actually pressing on the types, from contact with the cylinders, is very much less than that brought to bear on them by the platten of the Stanhope press; but as it acts on a smaller surface at a time, the amount of pressure on each part, successively, greatly exceeds that received by any similar portion when it is impressed all at once. The difference of the action of the platten and of the cylinder may be compared to the different effects produced by a knife when pressed with its edge and with its flat side against a yielding surface; the pressure on the flat surface may not be sufficient to leave any impression, whilst a much smaller pressure on the edge will produce an indentation.

The accompanying woodcut is a representation of one of Messrs. Applegath and Cowper's machines for printing both sides of the paper at the same time.

It consists of a cast-iron frame, about 14 feet long and 4 feet wide, on which the iron table, with the types upon it, slides backward and forward under two large cast-iron cylinders, covered with blankets, whereon the paper is laid. The pages of type to be printed on one side of the paper, and those pages that are to be printed on the back, are wedged into iron frames, called "chases," and these chases are fixed on the table at such a distance from each other, that they will pass under the two cylinders in the same relative positions. The sheets of paper are held on to the cylinders at their edges by means of tapes, and are so laid on by the workmen, that the type may be impressed on them with an equal margin all round. At each end of the machine is a supply of ink, which is taken from long iron rollers, about three inches in diameter, each of which turns in contact with a flat iron bar, that only allows a small quantity of ink to pass. A composition inking roller is made to vibrate between the inking table, where on the ink is thinly and evenly spread, and the iron feeding roller, and thus delivers the requisite quantity of ink on to the table. Several other composition rollers are placed across the inking table, with their axes resting in notched bearings, so that as the inking table moves forward and backward, those rollers distribute the ink evenly over it. There are four other rollers (none of which are shown in the diagram), which take the ink from the table; and as the types pass from under the cylinders, after printing a sheet, and return to them, they pass twice under the inking rollers. Each sheet of paper is laid by a boy on a web of tapes, by which it is carried round one paper cylinder, and then over and under two wooden drums to the other paper cylinder. The sheet of paper, in the course of its progress, is turned over, so as to receive the second impression on the other side; and as the tapes that carry it along leave the second cylinder, they divide, and the printed sheet falls into the hands of a boy.

In the printing machine which was shown at work in the Great Exhibition, invented by Mr. Applegath and made by Mr. Middleton, for printing the Times, the arrangements differ materially from those of the horizontal machines already described. The types, instead of being placed on a table, and moved to and fro under the impressing cylinders, are fixed to a large vertical cylinder, upwards of 16 feet in diameter, and there are eight impressing cylinders ranged vertically round it, with their axes fixed. By this arrangement there is no loss of time in withdrawing the types from under the cylinder to be again inked, but they move round from one fixed cylinder to another, receiving their ink between each, and thus producing eight impressions in succession during one complete revolution. At the Times printing office there are now three machines of that construction, two of which, with eight cylinders, print ten thousand an hour, and the other one, which has nine impressing cylinders, thirteen thousand.

The operations for printing that newspaper exhibit marvellous efforts of human ingenuity and skill, brought to bear in producing with the requisite rapidity a sufficient number of impressions to supply its enormous circulation. After the types have been composed and corrected, and ranged into columns and screwed up into their chases by upwards of one hundred hands, each page of type is attached to the large vertical cylinder—a curved form having been given to the type to adapt it to the circular surface. Nine men, standing each one beside a heap of damped paper, feed the largest machine by separating the sheets singly from the heap, and present them successively to the action of small rollers, that give each sheet a forward impulse, which brings it within the grasp of a series of endless tapes. These tapes catch hold of the sheets of paper, and carry them down to the level of the types. They are then shot along horizontally to the pressing rollers, covered with blankets, round which they are carried and pressed against the types; after which the endless tapes carry them away, and deliver them printed to a man below, who spreads them one over the other. A large reservoir of ink at the top of the machine supplies the inking tables, from which it is spread evenly over the inking rollers, and, at each revolution of the type cylinder, nine sheets are printed on one side. They are then taken to a second machine to be printed on the back, or, as it is called, "perfected." The accompanying engraving shows the general arrangement of the machines.

Few mechanical contrivances present so striking an illustration of the application of human ingenuity to the production of important results, and to the saving of labour, as these printing machines. To see the sheets of paper travelling along the tapes—to see them shoot downwards, carried sideways in one direction and back again, and delivered with half a million of words impressed upon them in less than three seconds, seems like the work of magic. To copy that number of words, thus printed in three seconds, would occupy a rapid penman forty days, working ten hours a day.

Great as are the printing powers of these machines of Mr. Applegath's, they have been surpassed more recently by one placed close beside them, invented by Mr. Hoe, of New York. In that machine the type cylinder is placed horizontally, by which means the paper is supplied directly to it without altering its direction. As many as twenty thousand impressions in an hour have been produced by the American machine, but it is not yet sufficiently perfected to be brought into regular use.