736 



PAPER ENVELOPES, BAGS, ETC. 



being used to facilitate creasing and turning 

 up the flaps. Subsequently sheet-iron dies 

 were made, with which the paper was creased 

 preparatory to gumming, and the operation 

 was completed with a bone folder. 



All envelope-making machines deal with the 

 "blanks," as they are called, namely, lozenge- 

 shaped pieces of paper prepared beforehand. 

 The early methods of cutting have been de- 

 scribed. The modern method requires a steel 

 die, shown in Fig. 2, which is placed on a pile 



FIG. 2. ENVELOPE-CUTTER. 



of 250 sheets of paper, and forced through 

 them all at once under a powerful press. A 

 is the pile of paper ; B, the thick upper edge 

 of the die, and C, 0, C, its lower or cutting 

 edge. The outline of the die sufficiently indi- 

 cates the general shape of envelope-blanks, 

 though it is varied according to fancy or spe- 

 cial requirements. A die of this kind costs 

 about $15, and has to be made of the finest 

 steel, in order to stand the tremendous pressure 

 and retain its keenness of edge. 



In some machines an attendant feeds the 

 blanks one at a time, laying each sheet upon a 

 table, where the side and the bottom flaps 

 are touched with gum and carried forward to 

 be folded, an operation which is performed in 

 different ways by different machines. In the 

 original De la Rue machines (Fig. 3) there 



JQL 



FIG. 3. DE LA RUE MACHINE. 



was a rectangular opening, B, the size of the 

 intended envelope. The blank (represented 

 by a dotted line in the figure) was placed over 

 this, and a plunger (A) descended upon it, 

 pressing it down through the opening upon a 

 lower table, the flaps being of course bent up- 

 ward (C) against the sides of the plunger. In- 

 stantly the plunger was withdrawn, and four 



hinged folders, corresponding in shape with 

 the flaps of the envelope, folded down the 

 already gummed flaps, and the work was 

 done. The finished envelope fell into a recep- 

 tacle, and the operation was repeated at the 

 rate of about sixty in a minute. The verbal 

 description seems very simple, but in point of 

 fact the operation involves a number of eccen- 

 tric movements that call for very nice calcula- 

 tion and adjustment. These movements are 

 effected by cams so adjusted that with clock- 

 like regularity the folders move when the 

 plunger rises, and retire after having done 

 their duty. The gummed rollers are always 

 exactly in position when the plunger begins 

 to descend, and all this reciprocal action goes 

 on without a hitch. 



A large majority of the machines in use em- 

 ploy this device of a plunger and its attach- 

 ment. Some of the modern improvements 

 point to a different system, indicated in Fig. 

 4, where the blank is carried by arms and roll- 

 ers under a thin metal slab, D, over which the 

 side and bottom flaps are folded with hardly 

 a perceptible check in the onward progress of 

 the envelope. These machines are peculiar, in 

 that the blank st-.irts, as it were, at one end of 

 a table some five feet long by two and a half 

 feet wide, and is delivered finished at the other 

 end, with scarcely a pause, after its edge is first 

 lifted by the device described farther on. It 

 is adjustable for any ordinary size of envelope, 

 and will turn out 120 or more in a minute. 

 Until recently machines have been practically 

 non-adjustable that is to say, they could be 

 changed from one size of envelope to another 

 only at a considerable loss of time. This was 

 especially the case with the plunger-machines, 

 where several changes had to be made in the 

 principal attachments. The machine described 

 in connection with Fig. 4 is readily adjustable 

 to any ordinary style of envelope, and does its 

 work more smoothly and directly than any of 

 the plunger-machines. 



One of the difficulties in gumming envelopes 

 by machinery lies in the seal-flap the one that 

 serves to close the envelope. The other flaps are 

 pressed together as soon as they are gummed, 

 and left to adhere where they are intended to 

 remain ; but, in order to gum the seal-flap by 

 machinery, it must not be allowed to touch 

 anything until it has had time to dry, and be- 

 come harmless to itself as well as to the other 

 clean envelopes with which it may be brought 

 in contact in packing for shipment. In the early 

 machines, many of which are still in use, th* 

 blanks were gummed by hand, and dried be- 

 fore being fed to the machine, but the difficul- 

 ty was overcome by providing wire racks fix< 

 upon a slowlv running band. \Yhen the side 

 and bottom flaps had been gummed and folded, 

 the seal flap was gummed and creased for fold- 

 ing, but before the operation was completed " 

 was dropped into the wire racks and mad< 

 a journey of about three minutes' duratioi 

 through a moderately warm current of 



