CHAMBERS'S INFORMATION FOR THE PEOPLE. 



This is obviously a matter of great importance 

 with books which require to be reprinted fre- 

 quently. 



Electrotyping. This process, which is described 

 in Vol. I. p. 276, is sometimes used in letter-press 

 printing when the plates are wanted to print a 

 great number of impressions. Wood-cut illus- 

 trations are generally electrotyped, the paper pro- 

 cess of stereotyping, owing to the damp and heat, 

 being quite unfit for the purpose. The illustrations 

 are electrotyped separately, and soldered into the 

 plate of letter-press. 



PROCESS OF PRINTING. 



The duties of the compositor differ from those 

 of the printer. When the forms are duly pre- 

 pared in the composing-room, and if it is intended 

 to print from them, and not from plates, they are 

 carried into the press-room, where they come 

 under the charge of the pressmen. The earliest 

 printing-presses were exceedingly rude, and seem 

 to have resembled the common screw-press, with 

 a contrivance for running the form under the point 

 of pressure. This must have been not only a 

 laborious and slow operation, but one exceedingly 

 defective, from the difficulty of regulating the 

 impression, and the risk of injuring the faces of 

 the types. The defects in these original presses 

 were at length remedied by an ingenious Dutch 

 mechanic, Willem Jansen Blaew, who carried on 

 the business of a mathematical instrument-maker 

 at Amsterdam. He contrived a press, in which 

 the carriage holding the form was wound below 

 the point of pressure, which was given by moving 

 a handle attached to a screw hanging in a beam 

 having a spring, which spring caused the screw 

 to fly back as soon as the impression was given. 

 This species of press, which was almost entirely 

 formed of wood, continued in general use in every 

 country in Europe till the beginning of the present 

 century. 



With certain lever-powers attached to the screw 

 and handle, it is represented in fig. 4. 



In connection with this representation of the old 

 common hand-press, the process of printing may 

 be described. The form, being laid on the sole or 



Fig. 4. 



bed of the press (s), is fixed at the sides, so as to 

 render it immovable from its position. There are 

 two men employed : one puts ink on the form 



760 



(see below), and the other works the press. The 

 latter lifts a blank sheet from a table at his side, 

 and places it on what is called the tympan (/), 

 which is composed of parchment and blanket 

 stuff, fitted in a frame, and tightened like the top 

 of a drum and hence its name and which, by 

 means of hinges connecting it with the sole, folds 

 down like a lid over the form. As the sheet, how- 

 ever, would fall off in the act of being brought 

 down, a skeleton-like slender frame, called a 

 frisket (/), is hinged to the upper extremity of 

 the tympan, over which it is brought to hold on 

 the paper. Thus, the frisket being first folded 

 down over the tympan, and the tympan next 

 folded down over the form, the impression is 

 ready to be taken. This is done by the left hand 

 of the pressman winding the carriage below the 

 platten (p) or pressing surface, and the impres- 

 sion is performed by the right hand pulling the 

 handle attached to the screw mechanism. The 

 carriage is then wound back, the printed sheet 

 lifted off, and another put on the tympan, the 

 form again inked, and so on successively. 



One of the greatest niceties connected with 

 this art is the printing of the sheet on the 

 second side in such a manner that each page, nay, 

 each line, shall fall exactly on the corresponding 

 page and line on the side first printed. To pro- 

 duce this desirable effect, two iron points are 

 fixed in the middle of the sides of the frame of 

 the tympan, which make two small holes in the 

 sheet during the first pressure. When the sheet 

 is laid on to receive an impression from the second 

 form, these holes are placed on the same points, 

 so as to cause the two impressions to correspond. 

 This is termed producing register; and unless 

 good register is effected, the whole effect of print- 

 ing, and afterwards folding and binding, will 

 be greatly marred. Expert workmen perform 

 these operations with surprising rapidity, though 

 with considerable labour. Two men employed 

 at a press take the process of pulling and inking 

 for alternate quantities. After the forms are 

 wrought off, they are washed in a solution of 

 potash, to remove the remains of the ink, which is 

 of a thick oleaginous character, and then carried 

 back to the composing-room to let the types be 

 distributed in the cases ; this operation, like that 

 of setting, is very speedily performed by the com- 

 positors. If the printing be done by plates, these 

 are cleaned and put by for future use. 



To suit paper for printing, it is necessary to wet 

 it some hours previous to its being used. This 

 is done by dipping alternate quires in water, and 

 afterwards pressing the mass with a heavy weight, 

 or by the screw or the hydraulic press, till the 

 whole is in an equally damp state. 



After the sheets are printed, they are hung upon 

 parallel bars in the drying-room to be dried a pro- 

 cess which is effected slowly or speedily according 

 to the degree of heat applied. On being dried, they 

 are individually placed between fine glazed boards, 

 and in this condition subjected in a mass to the 

 pressure of a powerful press. On removal, the 

 indentations of the types are found to be levelled, 

 and the whole sheet to be smooth, and ready for 

 the operations of the folder and bookbinder. 

 A great improvement has been effected in the 

 smoothing process, by employing the hydraulic or 

 water press, and by the process called hot-press- 

 ing. 



