Art. 14.-To find the tonnage of a ship. Rule.-Multiply the length of the keel by the breadth of tho heam, and that product by the depth of the hold, and divide the last roduct by 95, and the quotient is the tonnage. EXAMPLE Suppose a ship 72 feet by the keel, and 24 feet by the beam and 12 feet deep; what is the tonnage ? 72X24x 1295=218,2+tons. Ans. RULE II. Multiply the length of the keel by the breadth of the beam, and bat product by half the breadth of the beam, and divide by 95. EXAMPLE. A ship 84 feet by the keel, 28 feet by the beam; what is 112 tonnage? 84 x 28 x 14:95=350,29 tons. Ans. 2 lrt. 15.—From the proof of any cable, to find the strength of another. RULE.—The strength of cables, and consequently the weights of heir anchors, are as the cube of their peripheries. Therefore ; As the cube of the periphery of any cable, Is to the weight of its anchor; EXAMPLES. 1. If a cable 6 inches about, require an anchor of 21 cwt. of what wcight must an anchor be for a 12 inch cable ? As 6 x 6 x 6 : 24 cwt. : : 12 x 12 x 12 : 18 cut. Ans. 2. If a 12 inch cable require an anchor of 18 cwt. what nust the circumference of a cable be, for an anchor of 21 ewt. ? cut. cut. in. As 18 : 12 x 12 x 12 : : 2,25 : 216 9216=6 Ans. ART. 16.-Having the dimensions of two similar built ships of a different capacity, with the burthen of one of them, to find the burthen of the other. RULE. The burthens of similar built ships are to each other, the cubes of their like dimensions. EXAMPLE. If a ship of 300 tons burthen be 75 feet long in the ke I deniand the burthen of another ship, whose keel is 1 feet long? . T.cwt. grs. lb. As 75x75x75:300 : : 100 x 100 x 100:711 2 0 24 DUODECIMALS, OR CROSS MULTIPLICATION, IS a rule made use of by workmen and artificers in casi ing up the contents of their work. RULE. 1. Under the mulplicand write the corresponding deno minations of the multiplier. 2. Multiply each term into the multiplicand, begivning at the lowest, by the highest denomination in the multiplier and write the result of each under its respective term; ob serving to carry an unit for every 12, from each lower dos nomination to its next superior. 3. In the same mamner multiply all the multiplicand lus the inches, or second denomination, in the multiplier, and set the result of each term one place removed to the righ: hand of those in the multiplicand. 4. Do the same with the seconds in the multiplier, setting the result of each term two places to the right hand of those in the multiplicand, &c. EXAMPLES. F.I. 91 10 1 Product, 33 2 9 TO MEASURE LOADS OF WO01), Rule.-Multiply the length by the breadth, and the product by the depth or height, which will give the content in solid feet; of wk ch 64 make half a cord, and 128 a cord. EXAMPLE. Ilow many solid feet are contained in a load of wood. 7 feet 6 inches long, 4 feet 2 inches wide, and 2 feet 3 inches high? 7 ft. 6 in.=7,5 and 4 ft. 2 in. =4,167 and 2 ft. 3 in = 2.25 ; then, 7,5 x 4,167=31,2525 X 2,25=70,318125 solid feet, Ans. But loads of wood are commonly estimated by the foot. allowing the load to be 8 feet long, 4 feet wide, and then 2 feet high will make half a cord, wbich is called 4 feet of wood; but if the breadth of the load be less than 4 feet, its height must be increased so as to make half a cord, wnich is still called 4 feet of wood. By measuring the breadth and height of the load, the content may be found by the following Rule.-Multiply the breadth by the height, and half the product will be the content in feet and inches. EXAMPLE. Required the content of a load of wood which is 3 feet 9 inches wide and 2 feet 6 inches high. By Duodecimals. By Decimals. F. in. F. 3 9 3,75 2 6 . 2,5 1875 1 10 6 750 94. 6 9,375 --- F. in. Ans 4 8. 3 4,68754 81 or half a cord and El inches oor. The foregoing method is concise and easy to those who are well acquainted with Duodea.nals, but the following table will give ho sontent of any load of wood, by inspection only, sufficiently exant for common practico; which will be found ver Ennvenient. TO USE THE FOREGOING TABLE. First measure the breadth and height of your load to the nearest average inch; then find the breadth in the left hand column of the table, then move co the right on the same line till you come under the height in feet, and you will have the content in inches, answering the feet, to which add the content of the inches on the right and divide the sum by 12, and you will have the true routent of the load in feet and inches. Note: The contents answering the inches being always small, may ge added by inspection. EXAMPLES 1. Admit a load of wood is 3 feet 4 inches wide, and 2 feet 10 inches nugove required the content.- Thus, ag:ust 3 feet 4 inches, and under 2 feet, stands 40 inches; and un der 10 inches at lop, stands 17 inches: then 40+17557, true content in inches, which divide br 12, rives 4 feet 9 inches, the answer. 2. Tize leadth being 3 fet, and height 2 feet 8 inches; required the content Thus, with breadth 3 loet 0 inches, and under 2 feet ator, stando 36 |