The perforations are made through the metal, either by engraving, by etching with nitric acid diluted with about pne-third water, or, what is better, by both methods combined. If engraving only is employed, the force necessarily, applied to the graver will sometimes stretch the plate unequally, whereas by etching alone, the edges of the perforations are left rough, and the corners imperfect; but if the line be lightly etched, and afterwards cleaned with the graver, it may be rendered perfect without any risk of cockling the plate. If the back of the plate is smeared with a little oil, the cuttings will come out clean. A good ground for the etching of these plates is made by rubbing on them, slightly heated over a spirit lamp, a cake of heel-ball.

Copper is much better than brass for stencil plates; the metal being softer, it lies closer to the paper upon receiving the pressure of the stencilling brush. This close contact is a very important consideration, as it prevents the hairs of the brush from getting under the plate, and producing rough edges.

Plain stencil alphabets will not be necessary to a draughtsman, if he is a good writer, as they will only save him a little time. A greater saving may be effected by the use of words which are constantly recurring; as Ground plan, Front elevation, Section; or of interiors, as Drawing-room, Kitchen.

For railway or public works, headings of plans may be cut in suitable character and style; also words which are frequently repeated on any particular works, as the name and address of the architect or engineer.

Besides letters and words, there are many devices by the use of which a superior effect may be produced, and much time saved; of these may be mentioned, north points, plates for the representation of surface of country, as plantation, wood, or marsh, corners and borders for finished plan?, and many other devices.