MOTION. 60 seconds, marked" make 1 minute, 60 minutes, 1 degree, 30 degrees, 1 sign, S. 12 signs or 360 degrees, the whole great circle of the Zodiac. This table is of but little use to boys in common schools; it belongs to the higher orders of men in science, who are studying astronomy. However, a table like the following might be useful to boys, especially to those who intend to learn the art of surveying; but, as instruments and delineations of triangles, circles, &c. are necessary when we are working in rules of this kind, I shall only insert a few useful problems for the practical surveyor, and pass on to Reduction of Money. SURVEYOR's TABLE. 60 seconds, make 1 minute, 60 minutes, 1 degree, 90 degrees. 1 quadrant, Q. 4 quadrants 1 full and complete circle. 1. How to find a true corner, or to run a direct line from one known object to another, when there is a variation of compass. Suppose we begin at A, and run S. 82° W. 20 chains and 10 links, wishing to hit a beech corner tree; but by variation of compass, come out 30 links northerly from the corner; how many minutes variation are there ? Answer, 51 minutes. Therefore the line must be retraced N. 81° 9' E. from the beech tree to the place of beginning. RULE. As the distance run, Multiply 57.3 degrees by is to 57° .3; 30 links and divide that pro duct by the distance run, viz. So is the 30 links, 20 ch. 10 L. or 2010 links, the to the variation required. llquotinet will be the answer. Here note: If the divisor cannot be contained in the pro duct, multiply by 60 to reduce the product into minutes ; then divide, and the quotient will be the answer in minutes. OPERATION. 30 links, the third term or multiplier. 1719.0 60 minutes in a degree. 2010)103140.0(51 minutes variation. 10050 82° .. 2640 2010 00 course rün. .630 81 09 true course at present. Here the remainder is omitted, because we cannot run to a fractional part of a minute. RULE FOR PROOF. As the sum of the hypothenuse and half the longest leg, is to 86 degrees; so is the shortest leg, to its opposite angle. But in this case, the lines run so near a parallel direction with each other, that there is no material difference in their length; therefore we add half the base to the whole base, and call it equal to the hypothenuse and half the longest leg; or we consider the hypothenuse and base of equal length. OPERATION. 2580 60 minutes in a degree. Continued. 154800 minutes for a dividend. 2010 links, distance run. 3015 for a divisor: the quotient will be the proof in minutes. 15075 .. 4050 3015 1035 NATURAL RADIUS. RULE. 1. Take the opposite angle of the side sought, and divide 4 times the square of its complement to 90 degrees, by 300 added to 3 times the said complement. 2. Add the quotient to said angle, their sum will be natural radius. EXAMPLE In the following figure or triangle, the hypothenuse A C, and the angle at A, are given to find the side B C. с 90° 00' 46 30 7569.00 four times the square for a dividend. Continued. REDUCTION OF MONEY. The denominations of English money are inserted on Card No. 12. LESSON 1. In £ 2691 13s. 2d. how many pence? Ans. 645998d. OPERATION. 2691 pounds 13s. 2d. 20 shillings in a pound, 53833 s. 12 pence in a shilling. 645998d. When multiplying by 20, add in the 13s. when multiplying by 12, add in the 2d. ! = 365 LESSON 2. many pounds? Ans. 365 pounds. OPERATION, 87600:12 12)87600 =7300:20 210)73010 £ 365 LESSON 3. LESSON 1. In £916 10s. 9d. 39. how In £77 14s. 7d. 29. how many farthings ? Answer, many half-pence? Answer, 679379qrs. OPERATION 37311 half-pence. OPERATION. £ d. 20 9. 2 77 14 7 2 20s. in a pound. 18330s. 12 1554 shillings. 12d. in a shilling 219969d. 4 2 grs. in a half-pence, 916 x 20 + 10 = 18330 X 37311 half-pence, 12 + 9 = 219969 X 4 + 3 = $79879. s. 18655 pence. 879879 qrs. |