16. Painting in oil, as applied to the execution of designs, seems to have been invented, or at least to have been brought into notice, in the early part of the fifteenth century, by John Van Eyck, of Flanders. Before this time, house-painting, so far as the exterior was concerned, could have been but little, if at all, practised. 17. One profitable branch of common painting is that of painting and lettering signs. In performing this kind of work, the sign is first covered with two or three uniform coats of paint. The letters are next slightly sketched with chalk or a lead-pencil, and then formed in colors with a camels'-hair brush. When the letters are to be gilt, the process, so far, is precisely the same. The leaf is laid upon the letters, while the paint is in a tenacious state, and is suffered to remain untouched, until the oil has become dry, after which the superfluous gold is removed. The whole is then covered with an oil varnish, which, in plain lettering, completes the operation. THE GLAZIER. 1. Glazing, as practised in this country, consists chiefly in setting panes of glass in window-sashes. In the performance of this operation, the glazier first fits the panes to the sash by cutting away, if necessary, a part of the latter with a chisel; he then fastens the glass slightly with little pieces of tin, which have been cut to a triangular shape; and, lastly, he applies _putty_ at their junction with the sash, and by this means confines them firmly and permanently to their place. The putty is made of linseed-oil and whiting. The latter of these materials is chalk cleared of its grosser impurities, and ground in a color-mill. 2. Plain glazing is so simple, that no person need serve an apprenticeship to learn it; and there are but few who confine their attention to this business exclusively. It is commonly connected with some other of greater difficulty, such as that of the carpenter and joiner, or house and sign painter, but with the latter more frequently than any other. 3. When the glass, as received from the manufacturer, may not be of the size and shape required for a proposed application, the panes are cut by means of a diamond fixed in lead, and secured by a ferrule of brass, which is fastened to a small cylindrical handle of hard wood. This instrument is used, in conjunction with a straight edge, like a pencil in ruling lines on paper for writing. The glass is afterwards broken in the direction of the fracture, by a slight pressure downwards. 4. Although glass windows seem to us to be indispensable to comfort, yet glass had been manufactured many centuries in considerable perfection, before it was applied to this purpose. The houses in oriental countries had commonly no windows in front, and those on the other sides were provided with curtains, or with a moveable trellis-work in summer, and in winter with oiled paper.