[Illustration: Envelope-making machine.] We may notice one other article of almost universal use, which is of very recent introduction--the Envelope. It is a labour-saving contrivance for the writer of letters. The use of the envelope has been mainly created by the penny postage. We find, in the census, that seven hundred persons, chiefly females, are employed in making envelopes. But there is a beautiful machine also for making them, at the rate of twenty-five thousand a day. The envelope-making machine was one of the most attractive objects in the Great Exhibition. CHAPTER XIX. Labour-saving contrivances--The nick in types--Tags of laces--Casting shot--Candle-dipping--Tiring a wheel--Globe-making--Domestic aids to labour--Aids to mental labour--Effects of severe bodily labour on health and duration of life. We drew attention in the last chapter to a particular process in needle-making--the sorter's sheath--to show that great saving of labour may be effected by what is not popularly called machinery. In modern times, wherever work is carried on upon a large scale, the division of labour is applied; by which one man attending to one thing learns to perform that one thing more perfectly than if he had attended to many things. He thus saves a considerable portion of the whole amount of labour. Every skilful workman has individually some mode of working peculiar to himself, by which he lessens his labour. An expert blacksmith, for instance, will not strike one more blow upon the anvil than is necessary to produce the effect he desires. A compositor, or printer who arranges the types, is a swift workman when he makes no unnecessary movement of his arms or fingers in lifting a single type into what is called his composing-stick, where the types are arranged in lines. There is a very simple contrivance to lessen the labour of the compositor, by preventing him putting the type into his composing-stick the wrong side outwards. It is a nick, or two or three nicks, on the side of the type which corresponds with the lower side of the face of the letter. By this nick or nicks he is enabled to see by one glance of his eye on which side the letter is first to be grasped, and then to be arranged. If the nick were not there he would have to look at the face of every letter before he could properly place it. This is a labour-saving contrivance; and if the labour were not thus saved, two compositors would certainly be required to do the work of one; and the natural and inevitable effect would be that, as the funds for the payment of the compositor's labours would not be increased, the wages of each compositor would be diminished by one-half. The new labour that would be required would enter into competition with the old labour, and depreciate its value, because each individual labourer had lost one-half of his efficiency. [Illustration: Compositor at work.]