" rods," anil it is from these that the working lines are transferred to the material, or, as in the case of brickwork and masonry, the working templets are made. It might perhaps be convenient to distinguish these latter as "workshop " drawings, but, of course, the distinction would be a purely arbitrary one.
DRAWING INSTRUMENTS AND APPLIANCES— HOW TO USE THEM
The Drawing Board—sizes, materials, attachments, a reversible hoard. Squares — T square, most serviceable kind. Set Squares—useful sizes, various materials and their defects. French Curves. Instruments -choice of. Compasses--sizes, uses, etc. Ruling 1'en. Parallels. Protractors—description, various kinds, construction of. method of using. Drawing Papers—choice of, where obtainable, standard sizes. Pencils— degrees making compass pencils. Rubber- -kinds, and methods of using. Drawing Pins. Extractors. Drawing Inks--how to prepare and use. Tracing Paper anil Cloth—sizes and use of. Scales—description, making scales, the representative fraction method of dividing, diagonal scales, how constructed and read
The Drawing Board.—This is a flat board with its edges truly square and parallel, made in certain standard sizes to suit the paper generally used. The two most useful sizes for students are " half imperial," measuring about 16 in. x 23 in. x |- in. thick, suitable for elementary work, and " imperi;d," 32 in. x 23 in. x | in. for more advanced work: professional draughtsmen nearly always use a larger size, "double elephant," 28 in x4iin., but this size is seldom required by students. The drawing board may readily be made by a joiner, although it is hardly possible to obtain such well-seasoned and suitable material as that used by the leading firms of instrument-makers.
The best boards are made of American yellow pine, free from knots, square jointed and battened at the back, the battens fixed with domed screws sunk in slots and working on brass plates, to allow for swelling and shrinking of the board. In some makes the backs are grooved to prevent
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