PRINTING MACHINES. 



This general description will be more clearly understood by 

 reference to the following illustrative diagrams : 



Fig. 5 illustrates the operation of a single printing-machine. The form 

 A and the inking-slab B, are placed on a horizontal table ; above them is 

 the paper-cylinder D, the inking-rollers i i i, the diffusing-rollers c c, and 

 the rollers c, which supply the ink to the diffusing-rollers. The first of 

 these, o, is called the ductor roller. When the table x Y is moved towards 

 the left, from Y to x, the form A passes under the inking-rollers i i i, and 

 receives ink from them on the faces of the type ; at the same time the slab 

 B passes under the diffusing-rollers c c, and receives from them a supply of 

 ink to replace what it has just given to the inking-rollers. 



When the table is moved in the contrary direction, from x towards Y, the 

 form once more passes under the inking-rollers, and afterwards under the 

 paper-cylinder, which being pressed upon it, while it moves in exact accord- 

 ance with it, the types discharge upon the paper the ink they have just 

 received from the rollers ; and the printing of the paper being thus effected 

 on one side, the sheet is discharged from the tapes. The table is then 

 again moved to the left, and the types are again inked, and the same effects 

 ensue as have already been described. 



In this manner sheet after sheet is printed. 



The inking and diffusing-rollers rest upon the slab and 

 types by their weight, the axes projecting from their ends being 

 inserted in slits formed in upright supports, attached to opposite 

 sides of the frame which supports the moving table. The two 

 upright pieces in which the axes of each roller are inserted, are 

 not placed in exact opposition to each other ; the consequence of 

 which is, that the rollers are placed with their axes slightly 

 inclined to the sides of the table. This arrangement is attended 

 with a very important effect : for, in consequence of the friction 

 or adhesion of the rollers with the slab, they are moved alternately 

 in contrary directions with the longitudinal motion across the 

 table. This motion, combined with their rolling motion upon the 



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