Fowl rule

Devised by the Dept. of Agriculture and one of several formulas for estimating the volume of haystacks. First, measure the distance from the ground on one side of the stack, over the stack, and down to the ground on the other side. Multiply that number by the product of the stack width times the stack length and then by a factor, which varies from 0.25 to 0.37, depending on the specific stack shape, to get the volume of the stack in cubic feet. For other formulae, see the Frye-Bruhn rule, the Outlaw rule, and the Quartermaster’s rule.