AN ELEGANT COLONIAL STYLE RESIDENCE. (For floor plans, see back part of this book.)

Descriptions and Uses of the Various Markings on Rules and Squares, including the Slide-rule^ and how to use it. - Although the markings on rules and squares were made for the express convenience of workmen, yet but very few understand the uses of them. Every workman ought to be perfectly familiar with all of them, so as to avail himself of every advantage they afford. On Plate 37 will be found illustrations of the most important markings. Fig. 93 is the board-measure commonly found on the back of the blade of ordinary 2-foot squares. To find the number of square feet in a board, find the number representing the length of the board in feet in the column under 12 inches, then in the same line find the number of square feet under the number of inches in width. For instance: Suppose a board is 14 feet long, and G inches wide, in the column under 12 inches we find 14, the length of the board in feet: then on the same line, under 6 inches (the width), we find 7, which is the number of square feet contained in the board. Again, suppose the board is 8 feet long, and 5 1/2 wide, under 12 inches we find 8 (the length of the board in feet): then on the same line we find that (3/4 space beyond 3, which shows that the board contains 3 2/3 square feet, or 3 feet 8 inches. If the board is 12 feet long, then the number of inches in width will be the number of square feet contained in the board; or, if the board is 12 inches wide, then the number of feet in length will be the number of square feet contained in the board. Instead of finding the length in feet in the column under 12 inches, we may find the inches in width, then in the same line we will find the number of square feet under the number of inches that the board is feet in length. For instance: Suppose the board is 16 feet long, and 9 inches wide, under 12 inches we find 9, the width in inches: then under 16 inches, which represents 16 feet (the length), we find 12, which is the number of square feet which the board contains. If either the length or the width exceeds the figures on the square, find the square feet in a board of half the length or half the width, and double the result. Some say that this kind of board-measure is not exact, that it only approximates. This statement is not true. The whole number of square feet is found exactly where it occurs. For instance: A board 8 inches wide, which will contain 5 square feet, must be exactly 7 1/2 feet long; and it will be seen, by an inspection of the square, that the 5 occurs exactly under 7 1/2 inches on the square. It is not approximate: it is Exact.

Fig. 94 exhibits what is called "The Essex Board-measure," which is adopted by some makers. In this style of board-measure the number of square feet and inches, or square feet and twelfths, are found under every inch in length of the square. The number of square feet in a board is found in the same manner with this kind of board-measure as with the former kind. Suppose a board is 10 inches wide, and 14 feet long, under 12 inches we find 14 (the length in feet): then in the same line, under 10 inches (the width), we find 11-8, which represents 11 8/12 square feet.

PLATE 37.

See pp. 127 to 148.

Fig. 95 shows the brace-measure, which is marked on the tongue of squares. The two numbers at the left, one above the other, represent the runs in inches. The number and decimal at the right is the length of the brace in inches and hundredths. Thus, where the run is 57 by 57 inches, the length of the brace is 80.61 inches.

Fig. 96 shows the octagonal scale, which is found on the tongue of 2-foot squares. This scale is used to work from centre lines. If we desire to 8-square a stick of 10-inch timber, we first centre the width of each side, then, with a pair of compasses, take the distance from division 1 to division 10, and set it off on each side of the centre line; and by laying out both ends, and snapping a line, we have a guide to hew by. If the timber is 15 inches square, we take the distance from division 1 to division 15, and set it off on each side of the centre line as before. In many cases we are obliged to work from centre lines; as, for instance, when we 8-square a log, preparatory to rounding it, as in the case of mast and spar making, after having four sides flat, there is no corner to s;auo;e from.

Fig. 97 shows the octagonal scales usually found on rules. The scale marked M is the same as the octagonal scale found on 2-foot squares, only it is sub-divided finer, and works from the centre in the same manner. The scale marked E works from the edge or corner. If a stick of timber is 12 inches square, we gauge on from the eds-e the distance from division 1 to division 12 on the scale E; or, if it is 14 inches square, we gauge on from the corner the distance from division 1 to division 14.

Fig. 98 is a draughting-scale, full size, with six different scales marked off on it. The first one is 1/4 inch to the foot, or 1/4 inch = 1 foot: then comes 1/2 inch to the foot, 3/4 inch to the foot, 1 inch to the foot, and also 1 1/4 and 1 1/2 inches to the foot. The first foot of the scale 1/4 inch to the foot is divided into 6 parts, each part representing 2 inches. All the other scales have the first foot divided into inches. In using these scales to draw by, we begin to count the number of feet from the second foot, which is numbered 1, and count to the right: then, to get inches, we count to the left. For instance: If we are drawing with the scale of 3/4 inch to the foot, and we want to get 2 feet 5 inches, we set one point of a pair of compasses to 5 inches, counting from the right hand toward the left, then extend the other point of the compasses to the right till it reaches the 2 feet, which gives us the required 2 feet 5 inches, which we transfer to our drawing. These scales are usually scattered around when put on to the 3-jointed rules, but on single-jointed rules they are often all put together the same as seen in Fig. 98.