Bricklayers' Work. SECTION III. BRICKLAYERS' WORK. 1. ARTIFICERS' WORK in general, is computed by three different measures: viz 1st. The linear measure, or as it is called by mechanics, running measure. 2d. Superficial or square measure, in which the computation is made by the square foot, square yard, or by the square containing 100 square feet, or yards. 3d. By the cubic or solid measure, when it is estimated by the cubic foot, or the cubic yard. The work, however, is often estimated in square measure, and the materials for construction in cubic measure. 2. The dimensions of a brick generally bear the following proportions to each other: viz. Length twice the width, and Width twice the thickness, and = hence, the length is equal to four times the thickness. 3. The common length of a brick is 8 inches, in which QUEST.-1. By what measures is artificer's work computed? 2. What proportion do the dimensions of a brick bear to each other? 3. What is the common length of a brick-its breadth-thickness? How many cubic inches in a brick of 8 inches long? How many such brick make a cubic foot? Bricklayers' Work. case the width is 4 inches, and the thickness 2 inches. A brick of this size contains 8×4×2=64 cubic inches; and since a cubic foot contains 1728 cubic inches, we have 172864-27 the number of bricks in a cubic foot. 4. If the brick is 9 inches long, then the width is 42 inches, and the thickness 24; and then each brick will contain 9×4×291=cubic inches in each brick; and 1728 91; 19 nearly, the number of bricks in a cubic foot. In the examples which follow, we shall suppose the brick to be 8 inches long. PROBLEM I. 5. To find the number of bricks required to build a wall of given dimensions. RULE. 1st. Find the content of the wall in cubic feet. 2d. Multiply the number of cubic feet by the number of bricks in a cubic foot, and the result will be the number of bricks required. EXAMPLES. 1. How many bricks, of 8 inches in length, will be QUEST.-4. How many cubic inches in a brick 9 inches long? How many such brick in a cubic foot? 5. How do you find the number of bricks necessary to build a wall of given dimensions? Bricklayers' Work. required to build a wall 30 feet long, a brick and a half thick, and 15 feet in height? Ans. 12150. 2. How many bricks, of the usual size, will be required to build a wall 50 feet long, 2 bricks thick, and 36 feet in height? Ans. 64800. 5. NOTE. In these examples no allowance has been made for the mortar. The thickness of mortar between the courses is nearly a quarter of an inch, so that four courses will give nearly 8 inches in height. The mortar, therefore, adds nearly one-eighth to the height, but as one-eighth is rather too large an allowance, we need not consider the mortar which goes to increase the length of the wall. 3. How many brick would be required in the first and second examples if we make the proper allowance for mortar? 1st. 106314 Ans. { 2d. 56700. 4. Bricklayers generally estimate their work at so much per thousand bricks. To find the value of things estimated by the thousand, see Arithmetic, page 192. What is the cost of a wall 60 feet long, 20 feet high, QUEST.---5. How much space does the mortar between the courses occupy? What allowance then must be made for mortar in estimating the amount of bricks? Bricklayers' Werk. and two and a half bricks thick, at $7,50 per thousand, which price we suppose to include the cost of the mortar? If we suppose the mortar to occupy a space equal to one-eighth the height of the wall, we must find the quantity of bricks under the supposition that the wall was 17 feet in height. Ans. $354,372. NOTE.-In estimating the bricks for a house, allowance must be made for the windows and doors. OF CISTERNS. 6. It frequently occurs that cisterns are to be constructed which shall hold given quantities of water, and it is an useful practical problem to calculate their exact dimensions. 7. It was remarked in arithmetic, page 102, that a hogshead contains 63 gallons, and that a gallon contains 231 cubic inches. Hence, 231 × 63=14553, the number of cubic inches in a hogshead. 8. If, therefore, it is required to find the number of hogsheads which a cistern of given dimensions will contain, we have the following QUEST.-7. What is the number of cubic inches in a hogshead? How are they found? 8. Give the rule for finding the content in hogsheads of a cistern ? Bricklayers' Work. RULE. 1st. Find the solid content of the cistern in cubic inches. 2d. Divide the content so found by 14553, and the quotient will be the number of hogsheads. EXAMPLES. 1. The diameter of a cistern is 6 feet 6 inches, and height 10 feet: how many hogsheads does it contain? The dimensions reduced to inches are 78 and 120. To find the solid content, see page 165. Then, the content in cubic inches, which is 573404,832, gives 573404,832 ÷ 14553=39,40 hogsheads nearly. 9. If the height of a cistern be given, and it is required to find the diameter, so that the cistern shall contain a given number of hogsheads, we have the following RULE. 1st. Reduce the height of the cistern to inches, and the content to cubic inches. 2d. Multiply the height by the decimal ,7854. 3d. Divide the content by the last result, and extract the square root of the quotient, which will be the diameter of the cistern in inches. QUEST.-9. If the height of a cistern is known, how will you find the diameter, so that the cistern shall hold a given quantity? |