Printing
the art of producing impressions from characters or figures on paper or any other substance. Printing from movable types was, according to Professor Douglas, probably practiced in China as early as the 12th or 13th century, as there are Korean books printed from movable clay or wooden types in Among those which gained a large share of approbation was the Columbian press, press was taken to Great Britain in 1818 by George Clymer of Philadelphia, and patented. The pressing-power in this instance was procured by a long bar or handle acting upon a combination of exceedingly powerful levers. Printing is now executed by one or other of the varieties of cylinder presses, moved generally by electricity, or steam.
Printing machines may be divided into two distinct classes-those for printing books, in which accurate register is required, and those for printing newspapers, in which register is not sought for, and speed is of first consequence.
The printing business is divided into three departments-those concerned respectively with jobbing or commercial work, with book work, and with news work. Jobbing work is chiefly done on small platen machines invented by G.
P. Gordon, about 1868. Larger work is done on machines having one or more cylinders. It has been found, since machines have been brought to their present degree of perfection, that they give far superior results to those from presses -their impression is stronger, more solid, and more uniform, and the sheets can be laid on them with a precision unattainable with handpresses. Paper is not now made spongy and stretchable by being wetted, and the result of working it dry is that the type is brought up with greater brightness, and the delicate lines of engravings are printed finer, clearer, and cleaner. The colored sup- PRIOR plements of the pictorial journals are often admirable reproductions of works of high art. A single color press built in 1898 contained between 50,000 and 60,000 individual parts.
Books are generally printed in sheets of 16 pages, or multiples of 16 (32, 64, 128); in the latter case they are cut into sheets of 16 after being printed.
Several very ingenious machines have been invented for setting type which have been successful. They are worked something after the manner of typewriting machines. Several of the latest of these cast and set the type by one movement. This saves the labor of redistributing the types, as when done with they are melted again.
The latest achievement in printing machines is the combination color octuple rotary perfecting press. Four-roller distribution on the color portion insures fine work, and special oil-fountain arrangements take care of the offset. The printing is done from both stereotype and electrotype plates. The combination half-tone and color pictorial electrotype perfecting press is designed especially for printing, from electrotype plates, high-grade periodical work, with halftone and color illustrations.