STANDAKD WEIGHTS AND MEASURES 535 



site angle are given, take one-half the product of the side and 

 perpendicular, and divide by one hundred and sixty. 



When three sides are given, from half the sum of the three 

 sides subtract each side separately; multiply the half sum and 

 the three remainders together; the square root of the product 

 divided by one hundred and sixty will give the number of acres 

 in the field. 



AVhen the piece of land is in the shape of a trapezoid, take 

 one-half the product of the sum of the parallel sides and the 

 perpendicular between those sides, and divide by one hundred 

 and sixty. 



To find the area of any straight-sided piece of land, divide the 

 latter into convenient parts, find the area of every part, and the 

 sum mil be the area of the field. 



In general, the parts into which the field can be most conven- 

 iently divided will be triangles, but in some cases we may have a 

 rectangle or a trapezoid, whose areas may be found by the pre- 

 ceding rules. The area of a right-angle triangle equals one-half 

 the product of the two short sides. 



To ascertain the weight of cattle. — Measure the girth close 

 behind the shoulder, and the length from the fore part of the 

 should(?r blade along the back to the bone at the tail, which is 

 in a vertical line with the buttock, both in feet. Multiply the 

 square of the girth, expressed in feet, by five times the length, 

 and divide the product by twenty-one ; the quotient is the weight, 

 nearly, of the four quarters, in imperial stones of fourteen 

 pounds avoirdupois. For example, if the girth l)e seven feet, and 

 the length five and one-quarter feet, we shall have 6x6 — 36 

 and 51/4x5 — 261/4; then 36x2614 — 945, and this divided by 

 twenty gives forty-five stones exactly. It is to be observed, how- 

 ever, that in very fat cattle the four quarters will be aliout one- 

 twentieth more, while in those in a very lean state they will be 

 one-twentieth less than the weight obtained by the rule. 



Rule for measuring: corn. — A heaped busliel contains 2,748 

 cubic inches. To find the number of bushels of corn in a crib 

 it is therefore necessary merely to multiply together the length, 

 width and height in inches and divide the product by 2,748. The 

 number of bushels of shelled corn will be two-thirds of the quo- 

 tient. If the sides of the crib are slanting, it will be necessary 

 to multiply together one-half the sum of the top and bottom 

 widths, the height and length. 



Rule for estimating hay. — Hay is often sold in the mow or 

 stack where the weight has to be estimated. For this purpose 



