the cylinder K, is carried round the outside of the second printing cylinder E. By the time the paper is half round again, the second set of types has arrived under the cylinder E, and thus the second side of the paper is printed as it passes along between them. The sheet being thus perfected, is thrown out at O, where a boy sits to receive it. The object of the cylinders I and K is simply to convey the sheet smoothly from one printing cylinder to another. But how, it may be asked, is the sheet turned while it is passing through the machine to allow of its being printed on both sides?—By making the printing cylinders turn in opposite directions, and thereby passing the sheet down the outsides of them. If the sheet passed down the inside of the second cylinder E, the printed side would be presented to the second form of type: but by passing it outside, the paper is really reversed, and the. unprinted side is presented to the type. It is difficult to explain this in words; but any one may see it clearly by taking a piece of paper and passing it over two rollers which are moving in different directions, in a similar manner to the printing cylinders. The printing machine exhibits some other beautiful contrivances for the regulation of its working; but it would be impossible to represent them in an engraving, and they must be seen to be understood.

The speed of a single-cylinder machine is,

on the average, about 1000 sheets an hour, and of a double cylinder machine about 750 sheets an hour printed on both sides. The speed, as we have said, is limited by the power of feeding the machine with paper, and few men can lay on more than 1250 sheets an hour. But a far greater speed has been attained by increasing the number of cylinders. For instance, Messrs. Applegath and Cowper constructed for the proprietors of The Times, a machine which may be considered four machines in one. It had four printing cylinders, four feeding places, and four places where the printed sheet was thrown out, and the speed attained was 4000 impressions an hour.

But even this speed has been outstripped. The circulation of The Times, the name of which is inseparably connected with the progress of printing, has grown so large, that it became necessary to print it quicker than ever. The proprietors had recourse to Mr. Applegath, an engineer, who had previously done more than any other person for the improvement of the printing machine; and he has constructed one the simplicity of which is admirable, while its speed is practically without limit. It is a cylinder machine, but instead of the cylinders being placed horizontally as in the machine already described, they are placed vertically, that is, like a drum standing on one end. The type is also fixed on the surface of the central cylinder, which turns round continuously

instead of being placed on a bed or table, moving backward and forward under the printing cylinders. Before we proceed to give a particular description of this wonderful machine, we may perhaps be able to convey a rough idea of it by the following diagram.

These cylinders represent the cylinders of the machine. It must be borne in mind that they stand upright like so many columns, the opposite ends pointing towards the ground. The types to be printed are fastened on the surface of the central cylinder A, and the

whole of the cylinders turn round in the same direction. The small cylinders are really the printing cylinders.

A sheet is put in at each of the places marked by the arrow, it is drawn in by the motion of the machine and pressed against the large drum, and thrown out on the other side printed. Of course, it is so arranged that the type on the great cylinder shall arrive opposite each small cylinder at the instant that it is fed with a sheet of paper.

What we have just written simply illustrates the principle of the new printing machine. We will now endeavour to convey an idea of its details, taking for our example the superb machine by which The Times newspaper is printed. A large central cylinder or drum is erected, capable of being turned round on its axis. Upon the sides of this drum are fixed the columns of type by which the newspaper is printed, running straight up and down. The drum is 200 inches in circumference and 66 inches in diameter, and, therefore, the curve formed by its surface is so easy that the types stand almost square on their feet, just as men do on the round earth. The great drum is surrounded with eight smaller drums or rollers, also placed with the axis vertical, that is, like so many columns standing upright. Each of these cylinders is connected with the great drum by toothed wheels, in such a manner that their surfaces must move at exactly the same