hoppus foot (hft)
A British measure of the useful volume of sawlogs prior to the introduction of metric units, introduced by Edward Hoppus in the 18thC. The hoppus foot was intended as a measure of the volume of sawtimber after the log had been squared but prior to further conversion. 1 hft = 1.273 ft3. The formula for the hoppus foot deliberately underestimated the diameter at the mid-point of the log by dividing girth by four (to give ‘quarter girth’) instead of by p (3.16).