MECHANICS AND USEFUL ARTS. 55 



creases the envelope, and then opens so as to permit the partial folding 

 of it. 3. Four folders, two of which press down the corresponding 

 flaps of the envelope before the box is entirely raised ; the two others 

 follow with their pressure, after the remaining portion of the box is 

 lifted up. 4. Two finger-shaped projections, made of caoutchouc, 

 which, owing to their property of adhering to a paper surface, never fail 

 to carry off each envelope as fast as it is folded. Though there are 

 twenty-two movements for folding each envelope, and each succes- 

 sively performed with great rapidity (the several motions succeeding 

 each other), there is no blow or jar of any kind in the working of the 

 machine. This is the effect of a regulation of velocity produced by 

 cams. 



In" connection with this subject, we would also call attention to an 

 ingenious contrivance for identifying a letter with its envelope, recently 

 introduced into the Post-Office Department of Great Britain. It consists 

 of a set of perforations which, when the Post-Office stamp is used, 

 cause some portion of the ink to press through the envelope to the 

 inclosed letter, so that, when the two are put together, they complete the 

 lettering of the stamp. London Aihenceum. 

 * 



MACHINE FOR MAKING ENVELOPES. 



THERE is in operation, in Philadelphia, an ingenious machine for 

 the manufacture of envelopes, an article which, within a few years, since 

 the alterations in our postage-laws, has come into great demand. The 

 process of the manufacture is thus described. A pile of paper is first 

 laid under the cutting-press, and the flat forms of the envelopes are cut 

 out at once. These are then taken to the folding-machine, which is one 

 of the most singularly constructed and beautiful pieces of mechanism 

 we have ever seen. It requires but one person to feed it, and performs 

 all the rest of the operations itself; for the paper, cut in proper form, 

 being placed in a fixed position, is seized by nippers and drawn forward 

 to a bed, where^ it is held firmly by an over-hanging plate of metal, 

 which covers just so much as marks the size intended to be made, 

 leaving the parts to be folded over loose. The sides are then, by 

 means of plates advancing towards each other, folded over, and, as they 

 retire, a roller covered with gum passes under the surface of a double 

 curved piece of brass, which instantly falls upon the paper, and, as it 

 rises, another plate turns over the inside fold, while at the same time a 

 roller presses on it and causes adhesion. This being done, the bed on 

 which the envelope rests falls to an inclined position ; and, being caught 

 between rollers, the finished article is passed through a trough into 

 a receiving basket. The only remaining labor is to gather the envelopes 

 up and sort them into packages of twenty-five each. The whole is 

 done with great rapidity, and so various and contrary are the motions 

 of the machine, that it appears almost to be in some degree sentient. 



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