A knowledge of the properties and principles of lines can best be acquired by practice. Although the various diagrams throughout this work may be understood by inspection, yet they will be impressed upon the mind with much greater force, if they are actually drawn out with pencil and paper by the student. Science is acquired by study - art by practice; he, therefore, who would have anything more than a theoretical (which must of necessity be a superficial) knowledge of carpentry and geometry, will provide himself with the articles here specified, and perform all the operations described in the foregoing and following pages. Many of the problems may appear, at the first reading, somewhat confused and intricate; but by making one line at a time, according to the explanations, the student will not only succeed in copying the figures correctly, but by ordinary attention will learn the principles upon which they are based, and thus be able to make them available in any unexpected case to which they may apply.
The following articles are necessary for drawing, viz.: a drawing-board, paper, drawing-pins or mouth-glue, a sponge, a T-square, a set-square, two straight-edges, or flat rulers, a lead pencil, a piece of india-rubber, a cake of india-ink, a set of drawing-instruments, and a scale of equal parts.
The size of the drawing-board must be regulated according to the size of the drawings which are to be made upon it. Yet for ordinary practice, in learning to draw, a board about fifteen by twenty inches, and one inch thick, will be found large enough, and more convenient than a larger one. This board should be well seasoned, perfectly square at the corners, and without clamps on the ends. A board is better without clamps, because the little service they are supposed to render by preventing the board from warping is overbalanced by the consideration that the shrinking of the panel leaves the ends of the clamps projecting beyond the edge of the board, and thus interfering with the proper working of the stock of the T-square. When the stuff is well-seasoned, the warping of the board will be but trifling; and by exposing the rounding side to the fire, or to the sun, it may be brought back to its proper shape.