lever c'a during its predetermined motion, into 41 spaces, and beginning at a describe from the centre

Κ THE

VI

I

of the envelope-folding machine was formed. c, Fig. 880, is the centre of the cam, and c' the centre of the lever or follower. The extent of motion of this lever is first determined by means of the arc a a', which if prolonged would reach the centre c. The fraction of the revolution of the wheel, i. e. the time occupied in the motion of the lever, is also predetermined, and marked out by means of the arc rr.

With the radius cc draw an arc c' c", and from c set off the portion CIX, corresponding to the angle comprised between the radii rr'. Divide

this into any odd number of parts,

nine for example, numbered in a direction opposite to that of the motion of the cam, I, II, III, &c. Now by the laws of mechanics, a falling body moves in successive intervals of time through spaces corresponding to the odd numbers, 1, 3, 5, 7, &c., and as it is of advantage to give equal impulses to the machine, the same law is followed in the extent of motion given by the cam to the lever; but if this law were to operate until the end of the motion, a considerable shock would be given to the machine, since the body being set in motion would be moving at its greatest velocity by the time it had completed one revolution. It is therefore arranged that this law shall be maintained up to a certain point, or until the centre of the motion is arrived at, after which, the motion is continued with a velocity constantly decreasing in the same ratio as it before increased. For example, in the nine periods previously determined on, Period 1. a is moved through equal to 1 space

135

7

9

25

or as the square of the times

a space is moved through equal to 7

5

3

1

or in the inverse ratio of the squares of the times 41 We therefore divide the arc a a', described by the

III

c a circular are, passing through the zero or starting point of these divisions. In the same way, successive segments of circles are drawn from the centre c, at such distances as to pass through the 1st, 4th, 9th, 16th, 25th, 32d, 37th, 40th, 41st, divisions from a (corresponding to the spaces, 1,3,5,7,9, 7, 5, 3, 1), and intersecting the radii ar and a"?””. With the radius a c', placed successively at the intervals I, II, III, IV, &c. on the arc c'c", intersect the arcs 1,

II, III, IV, &c. A curved line a to Ix, drawn through these various intersections, is the centre line of one face of the cam. The lever might be made to return immediately to its former position, or to any intermediate position, but in the cam about to be described it is intended to remain for a certain period at rest; therefore, the centre line of that portion of the cam which is intended to keep the lever at rest, must evidently be a portion of a circle described from the centre c, and marked IX to s. The opposite face of the cam s d' is set out in precisely the same manner as the portion a IX, but it does not follow that it has the same form, because the elements may be different. The portion ad being a period of rest is likewise concentric to the centre c. From this centre line the half diameter of the roller or stud to be used on the follower of the cam is set off on both sides, so as to mark out a broad path having its two boundaries equi-distant at all points from the centre line ar r'a”. Within this path the roller travels in the same way as the pin in the grooved plate already described. A roller is used simply to diminish friction, and to prevent the abrasion and consequent change of form of the curved path.

In this machine all the cams are double; that is, the truck or roller attached to each of the levers is controlled in its motion by two surfaces, and not, as is often the case, by one surface, against which it is pressed by a spring. This latter method is objectionable on account of its absorbing a great amount of power; for unless the spring be strong enough to keep the truck in close contact, it is apt to fly off and produce shocks to the machinery, especially if the

steam engine or driving power should happen to be slightly accelerated in speed.

Each cam is formed by projection on a circular disc, the cam chace being counterbalanced by a projecting counterweight, cast opposite to its centre of gravity. Each lever is also constructed so as to be balanced when swung at its centre. In the case of the two levers 4 and 5 of the plunger 6, Fig. 884, their construction only admits of their being balanced by the counterweights 4", 4"".

The principle of the cam being clearly understood, we next proceed to describe the various parts of the folding machine in the order of their work.

The functions of this machine are, to fold envelopes previously cut into the proper shape, and to secure the folds thus made by means of gum. The machine is fed with blank envelopes by a boy, at the rate of about one per second, this being the rate at which the principal cam revolves. The seal stamp is embossed on each blank, and the gum immediately under the seal is applied before the blanks are brought to the folding machine. This machine might be so arranged as to stamp the seal and feed itself; but in order to stamp efficiently, the parts must be made considerably stronger than they are in this machine, and it seldom happens that a sufficient number of envelopes are required from one scal to render such an adaptation economical. Moreover, every additional motion introduced must retard the progress of a machine; so that in this instance it is found more advantageous to engage the services of a separate machine. Then as regards feeding, a self-supplying apparatus would not in this case be of great advantage, because as some one must be present to superintend the machine, it is better that he be employed than remain idly looking on, for in such case his attention is apt to flag, and by allowing badly folded or broken envelopes to get into the machine much mischief may be done. Some idea of the precision with which this folding machine works may be gathered from the fact, that on an average there is not more than 1 envelope in 2,000 badly folded, and these generally arise from defects in the paper.

F

The blank envelopes, or lozenges as they are called, are cut out 250 at a time with great rapidity and precision, by means of an instrument identical in its action with a common gun-punch. E and F, Fig. 881, show two forms of lozenges, and may also be taken to represent the steel cutting edge of the punch. In the plain lozenge form E there is little or no waste of paper in the cutting out; but in the fancy envelopes (which are really less elegant in form than the plain lozenge) the waste is often considerable. Thus it will be evident, that there must be a greater waste in cutting out F, than in E. The waste paper is returned to the paper-maker to be made into pulp.

Fig. 881.

The blanks are next stamped with a seal at the embossing-press, [see EMBOSSING-PRESS,] and the

folders 5' 5' 5'5'. As soon as the envelope is placed

Fig. 882.

T

Fig. 883.

on this table, the compound box or plunger 5, Figs. 884, 886, 887, is brought down by the cam 3 upon the table T, and this plunger descending with the table into the recess formed by the four axes of the folders 5', carries down the envelope and creases it in a rectangular form, the four triangular flaps standing up in a vertical direction. The ends of the plunger being moved by that side of the cam 3, shown by the dotted lines in Fig. 884, rise up so as to leave room for the two end folders 5'5' to turn over, not simultaneously, but one slightly in advance of the other, Fig. 883, so that one of the end flaps of the envelope may overlay the other. These two triangular folders are moved by the cams 6 and 7, in the order of the numbering. But before the other two flaps are turned over, it is necessary that gum be applied in the exact spot, in order to cause three out of the four triangular flaps to adhere. The gumming apparatus is seen separately in Figs. 888 and 889, the gummer being marked 10 in the other figures. After the two end flaps are turned down, this gumming apparatus is brought forward by the cam 11, and prints on the two end flaps a line of gum imparted to it by an endless blanket. During the whole of these operations, the sides of the plunger 5, which had remained down so as to prevent the envelope from being disturbed, are now moved upwards by the cam 3, seen best in Fig. 884, and remain up until the commencement of the folding of another envelope; the two end folders remaining down to secure the envelope, and the gumming apparatus retreating. The two triangular side folders are now turned over by means of the two cams 8 and 9, one having a little the precedence of the other. The four folders then open simultaneously, leaving the envelope complete; but as the flaps of the envelope would, from the elasticity of the paper, be liable to spring open, there is a contrivance for keeping them pressed down; for which purpose, the apparatus which removes each envelope as soon as it is folded also places it in a pile immediately under the one last folded.

The taking off and piling apparatus consists of a slide 12, hinged at 12', capable of rising and falling, and of a saddle 13', carrying the fingers 13", seen best in Figs. 856 and 887. This saddle moves in a hori

Fig. 885.

zontal direction on the slide 12. The points of the fingers move by a combination of these two motions, the vertical and the horizontal, in the line shown in Fig. 885, and in the direction of the arrows. After the envelope is folded, the fingers 13" are brought down into the recess formed by the axes of the folders 5', by means of the double cam 13, Fig. 887, one side of which is appropriated to the vertical motion of the slide, and the other to the horizontal motion of the saddle. When by these motions the fingers are brought into contact with the envelope, they are raised up, and at the same time the table T is made to rise with them, by means of a projection on the rim of the cam 3, Fig. 884, in such a manner as to keep the envelope firmly pressed against the fingers. The next motion of the fingers is the horizontal one; they are moved along the springing table 15, carrying the envelope with them, adhesion being promoted by tipping the points of the fingers with caoutchouc. As soon as the envelope reaches its destination under the pile, the slide is lifted by means of the cam 13, by which means the fingers are disengaged from the envelope, and they remain at rest until the next envelope is folded. The envelopes thus removed from the table are knocked over by means of a small beater 16, moved by a pin on the slide 12 on to an endless blanket 17, and pass under a small roller 18, which serves to Compress the folds of the envelope more closely to

gether. The envelopes then rise in a pile in the threesided trough 19, from which they are removed at intervals by an attendant.

On reference to Figs. 884, 886, 887, it will be seen that a series of racks 6" 7" 8" 9", serve to communicate motion from the levers 6' 7' 8' 9' to the wheels 6" 7" 8" 9"", affixed to the folder axes 5 5 5 5. The object of this is to allow of the transmission of motion to the folding apparatus for envelopes of various sizes. The levers and racks retain their position, the folder axes being adjusted either at a greater or a less distance from the centre of the machine, in case a larger or a smaller envelope be required to be folded. Were it not for this provision, the cams and levers would have to be reconstructed for every variation in the size of the envelope, or, in other words, a new machine would be required for every size of envelope

The gumming apparatus, shown separately in Figs. 888 and 889, requires some further notice. The cam 11, Figs. 884 and 888, gives motion to the lever 11', and this to the wheel 11", and the axis to which it is affixed. The prolongation of this axis carries a lever e, and is hinged to a small frame ff, which carries the gummer 10. The curved lever e' is linked to the opposite side of the frame ff, and serves to retain it always horizontal to the plane of the table T, so that when the former moves forward on to the envelope, its action is very similar to that of the closing of a parallel ruler. This gummer 10

lever worked by the axis 11”, and working in a ratchet wheel 22, fxed to one of the rollers of the exdess blanket. In Fig. 988, the two positions of the gun mirg apparatus are shown.

As the principal cam revolves at the rate of about one revolution per second, it is necessary to feed the machine when in motion with a blank envelope at that rate. If the boy neglects to feed at the proper time, ie, on the completion of one revolution, two things happen; the first and more serious one, is, that the gummer would place gum on the small table T, so that the next biank envelope would be, spoiled; secondly, the envelope which had been previously folded, and which by the arrangement of the taking off fingers is left projecting a little from the pile, would be knocked up in the heap, in consequence of which the succeeding envelope would enter the pile with so much difficulty, as to be crumpled up and spoiled, and it might also spoil several others. Both of these consequences are prevented by two stops, moved by the boy as soon as he fails to insert an envelope at the proper moment. The first stop being slid forward, touches a small lever 24, attached to the axis carrying the gummer 10, and lifts up this axis and the gummer as the frame is descending upon the table T; so that by this contrivance, as long as the stop remains in position, the gummer does not come in contact with the table: the second stop catches a projection 13"", affixed to the axis of the fingers 13", which are adjusted so as to turn in a small are of a circle, so that as the saddle 13' retreats along the slide 12, the fingers turn upwards and away from the projecting or leading envelope, as it is termed, which was previously folded. The slide in rising brings a projecting piece on the axis against a stop 14, which places the fingers in their usual position, and so long as the lad ceases to feed the machine (except, of course, when it is not at work) he leaves both these stops at rest; but as soon as he has fed the machine, he instantly removes them, and the operations proceed in the order previously described. By these simple contrivances, the waste of the

This ingenious and highly interesting machine was patented on the 17th March, 1845, by Edwm H.! and Warren De la Roe. An apparatus for cutting out the blanks was also included in the same patent. Previous to this date, envelopes were cut out by means of chise's, the paper having been roughly out to shape, and then held between two templates of the proper form. The envelopes were then folded by hand with the assistance of a common bone knife or folding-stick. A quick hand could on an average fold about 3,000 per day. Now the machine falls with a precision not attainable by hand, from 45 to 60 per minute; this is the average including al causes of stoppage; so that in a day of 10 hours, from 27,000 to 30,000 envelopes are completed, which when seen in a pile, appear as if they had all been cut to size by a knife.

In this machine, ecomony of space is as remarkable as rapidity of production and excellence of workmanship. This machine does the work of 10 skilful folders, and does not occupy more space than would be required by one folder. But it may be asked, is this really an advantage? Does not one of these machines deprive ten pairs of human hands of the means of earning bread? We have already examined this question in other articles of our Cyclopædia, and we again answer, No! If the 10 envelope folders who are superseded by 1 of these machines could absolutely do nothing else but fold envelopes, then they would suffer; but no one pretends that 10 busy, active and intelligent young women who have attained skill in this business, are incapable of quickly attaining skill in other occupations where activity and skill are required. Other occupations, it is true, may not be readily procured, and these 10 folders may for a time suffer from want of employment; but if our principle is true, that improved machinery increases employment among operatives, it is true in this case also, as the following details will show. The envelopefolding machine has made envelopes cheap, and as adhesive envelopes are convenient, the demand for them has surprisingly increased. Previous to the year 1839, envelopes were not used, because the Post Office charged double postage if one piece of paper were enclosed in another. The date of the Act for adopting postage reform, was 17th August, 1839, and