ENVELOPES. Before the introduction of the Penny Postage, the number of written letters put into envelopes was comparatively small ; but since that period the use of enve lopes has increased to an astonishing extent. The cutting out has been for some years per formed by machinery ; but the folding, until within the last three or four years, has been done by hand. An ingenious machine, how ever, patented by Messrs. Hill and De la Rue, now folds envelopes with great celerity. From a description of this folding machine given by Mr. Faraday at the Royal Institution in 1840, it appears that it can fold 42 envelopes in a minute. There is a fiat metallic surface on which the piece of paper is laid ; a sort of hollow frame descends and creases the paper at the four edges : and four levers or folders press down the four flaps of the envelope. There are two finger-shaped projections, made of caoutchouc, which, owing to their property of adhering slightly to a paper surface, never fail to carry off each envelope as fast as it is folded. Though there are twenty-two move ments'for folding each envelope, all succeed ing each other with great rapidity, there is no blow or jar of any kind in the working of the machine.
Mr. Worsdell's patent for making envelopes, enrolled in 1850, relates to mechanism of a very complicated construction. Under the usual methods envelopes are made partly by hand and partly by machinery, with certain intervals of time between the several processes. Mr. Worsdell has sought to carry on two or more of the processes simultaneously, and to make other processes succeed them uninter ruptedly. There are shaping, cutting, stamp
ing, gumming, creasing, pasting, and applying processes. A web of paper is unrolled, laid upon a bed or plate, and a series of fine knife edges descend and cut out a piece the proper size and shape for an envelope ; this same piece of paper, before it is removed, is creased into an oblong quadrangular form, and the four corners turned up. The roughly shaped envelope falls out of this machine, and is placed in another where the subsequent pro cesses are carried on. By one movement a die is brought down, and made to stamp a de vice on the seal-flap ; by another movement two bits of sponge, moistened with some kind of gum or cement, and held at the ends of small cylinders, are passed lightly over the edges of the two end flaps ; by a third move ment the sponges are brought back again ; by a fourth movement another bit of sponge, moistened with adhesive composition, is made to touch the inside of the seal flap ; by a fifth movement the three flaps are pressed down, leaving the seal flap, with its adhesive compo sition, untouched ; and by a sixth movement the finished envelope is thrust out of the ma chine. Considerable mechanical ingenuity is displayed in this apparatus.
It is supposed that there are upwards of a million envelopes manufactured daily in this country.