To find the cubical quantity in a trench, or an excavated area, the length, width and depth must be multiplied together. These are usually given in feet, and therefore, to reduce the amount into cubic yards it must be divided by 27.

Suppose a trench is 40 feet long, 3 feet wide, and 3 feet deep, required the number of cubic feet, or yards?

40 X 3 = 120 X 3 = 360 feet / 27 = 13} yards.

21 cubic feet of sand, 17 ditto clay, 18 ditto earth, equal one ton. 1 cubic yard of earth or gravel, before digging, will occupy about 1½ cubic yards when dug.