When all dimensions are in feet: Length × breadth × depth ﹦ cubic feet.
When one dimension is in inches: Length × breadth × depth ÷ 12 ﹦ cubic feet.
When two dimensions are in inches: Length × breadth × depth ÷ 144 ﹦ cubic feet.
For board measure, depth always equal 1 inch.
To find surface in square feet, proceed as per rules for solidity of square timber.
LAYING OUT OF AREAS.
1. In Squares.—Extract the square root of the desired content, reduced to square chains (ten square chains equal one acre). The result will be the length of the required side in chains.
Thus if we wish to find the side of a square block containing 25 acres, we first reduce the acres to square chains: 25 × 10 = 250, the square root of which is 15·81, or 15 chains 81 links; the side required.
By reference to the tables of square roots on page 189, the required sides of square block for a large number of acres can be read off at once.
One acre laid out as a square must have its side made 316¼ links, or 208-71/100 feet, or 69-57/100 yards, 70 paces being a near approximation.