The inking system of printing press is very elaborate. It is highly essential that the ink be spread upon the type surface in just sufficient quantity to be picked up by the paper and that the ink be uniformly distributed over the whole surface. There is an ink reservoir and a set of inking rollers for each cylinder. The reservoir consists of a trough running the whole length of the cylinder. At each turn a revolving roller dips into the ink and transfers a thin film of ink to a series of small rollers. These are grouped about a large roller to which they deliver the ink. The small rollers have an axial reciprocating motion whereby the ink is uniformly spread over the large roller. The latter transfers its thin coating of ink to a pair of rollers known as “form rollers” and these in turn deliver the ink to the printing cylinder.
A SEA CAPTAIN’S CONTRIBUTION
The folding mechanism of a printing press is interesting. The paper is first fed over a wedge-shaped form which folds the paper lengthwise and then it is given a cross-wise fold. Curiously enough the folding mechanism for printing presses was first invented by a Yankee sea captain, named Cromwell, who could not read a drawing but developed his invention by whittling out wooden models. He also contributed other valuable improvements for the printing press worked out in the same primitive way.
The rotary press was evolved especially for the printing of daily papers and for a long time magazines continued to be printed on flat-bed presses. But as the circulation of magazines grew into the hundreds of thousands it became necessary to build high speed presses to turn out these large editions. Accordingly rotary machines were constructed similar in design to newspaper presses, but with refinements to enable them to produce the better class of work required of magazine printing. Although there are many magazines still printed on flat bed presses, particularly those which publish small editions of less than a hundred thousand, all the big national weekly journals and monthly magazines are printed on rotary presses and some of them even use web presses.
GATHERING AND BINDING MAGAZINES
When a newspaper leaves the press it is folded, cut, and ready for the news stand. Not so with the book and magazine press. There are too many pages to be handled by a single press, and, furthermore, the pages must be bound together. Some large magazines contain regularly more than 500 pages and occasionally they will run over a thousand pages. Obviously no single press could handle so many pages and it takes the product of many presses to make up a single copy. Each press prints what is known as a form or signature and these signatures from the different presses are then gathered, wire-stitched, and bound into individual copies. There are machines which will do this work of gathering and binding at the rate of sixty 1,000-page magazines or catalogues every minute. The machines are adjustable for pages of different dimensions. The forms may consist of four, eight, sixteen, or thirty-two pages. A separate compartment is provided for each signature. A large machine will handle thirty-six 32-page signatures. The compartments are kept supplied by an operator, there being usually six compartments for each operator to attend to. The bottom signature in each compartment is brought into position by a suction device which seizes the signature and draws it out, depositing it in a steel trough. Here a belt conveyor moves the signature along at the right speed to carry it before the next compartment just as a signature is being withdrawn therefrom. Thus the magazine or book is progressively built up and the signatures reach the end of their course properly assembled. A very delicate adjustment is provided to insure the proper adjustment of signatures. The grippers are adjusted to receive signatures of a certain thickness. If the operator should make a mistake and put a signature of a wrong size in the compartment the whole machine would come to a standstill. The adjustment is so delicate that even a variation of a single thickness of paper is enough to operate the stop mechanism. Each assembly of signatures as it reaches the end of the trough is squared up and then bound with wire stitching. From this point it moves on to receive its cover. A thin coating of hot glue is applied to the rear edge of the signatures. The cover is automatically applied and firmly pressed into place. The finished book is then carried on out of the machine and deposited neatly on a pile of previously bound books. To operate such a machine there are required one chief operator and an assistant and six girls to feed the signatures to the compartments.
SETTING TYPE BY MACHINE
The publication of a modern daily newspaper with its many special editions would be well nigh impossible if we still had to depend upon hand setting of type. Tens of thousands of type characters are required to make up a single newspaper page, and although skilled hand compositors work with extreme rapidity it would take a large corps of men to set type for even a small newspaper in the short time available. Speed is of prime importance in newspaper work and the task of handling thousands of little pieces of type metal and arranging them correctly into words and sentences was long recognized as a serious handicap, but the problem of doing this work by machine was by no means simple one and baffled inventors for years. One of the principal difficulties lay in the size and shape of the type and another was that of justifying the lines, that is, providing just the right width of spaces between words to fill out the lines completely so that they would all be of equal length, giving a straight instead of a ragged margin to the column. After that came the problem of redistributing the type.
The first really successful composing machine was the invention of Ottmar Mergenthaler in 1888. Mergenthaler overcame the difficulties that had balked other inventors by attacking the problem from a radically new angle. Instead of setting precast type, his machine cast its own type from a set of matrices. By operating a keyboard, the matrices were assembled in a line which was justified automatically after the line was composed and then the whole line of type was cast in a single slug. Hence his machine earned the name “linotype.” Then the matrices were returned automatically distributed to the proper channels of the matrix magazine ready to be used over again for succeeding slugs.