SCIENCE IN THE INDUSTRIAL WORLD 



unwound, and weighing about 750 pounds. As the paper 

 unwinds it passes first over a jet of steam which slightly 

 dampens and softens its hard surface and fits it for re- 

 ceiving impressions, without leaving it wet or sodden. 

 It passes under a plate-cylinder, on which are thirty- 

 two curved plates, inked by seven large rollers, which 

 print thirty-two pages on one side. Then it passes 

 around a reversing cylinder which presents the other 

 side of the paper to another plate-cylinder, on which 

 are thirty-two plates which print exactly on the back 

 the proper pages for the thirty- two previously printed. 

 This is done quickly in less than two seconds but 

 with exactness. To do this it is drawn upward under a 

 small cylinder containing a concealed knife, which cuts 

 the printed web in strips two leaves wide and four leaves 

 long. As soon as cut the sheets are thrown forward 

 on endless belts of tape. An ingenious but undetecta- 

 ble mechanism gives to every alternate sheet a quicker 

 movement, so that it falls exactly over its predecessor, 

 making two lapped strips of paper. Busy little adjusters 

 now come into play, placing these lapped sheets of 

 paper accurately up to a head- and a side-guide. With- 

 out an instant of delay down comes a strong creasing 

 blade over the long center of the sheet and pushes it 

 out of sight. Pulleys at once seize the creased sheet and 

 press it flat, in which shape it is hurried forward to meet 

 three circular knives on one shaft, which cut it across in 

 four equal pieces. Disappearing for an instant from 

 view, it comes out on the other side of the upper end of 

 the tail of the press in the form of four folded sections of 

 eight pages each. Immediately after, at the lower end 



