Hoppus Foot (h ft)

The standard measure for round timber, derived from Edward Hoppus’s quarter-girth formula of 1736 and still used in tropical hardwood trading.

Hoppus published Practical Measuring Made Easy in 1736 and gave the timber trade a formula it could apply with a tape and no mathematics: take the girth of the log, divide by four, square it, and multiply by the length. The result deliberately falls short of the true volume, coming to about 78.5 per cent of it, and that shortfall is roughly the waste involved in squaring a round log into a usable baulk. The buyer therefore paid for the timber he could actually use rather than for the tree. The method proved so practical that it outlasted the empire that spread it: tropical hardwoods are still traded in hoppus feet across parts of the Commonwealth today.