Boning Rods: Three Identical T-Rods, 3 ft × 3 in × ½ in, Baker 1919

Boning rods are three identical T-shaped rods for setting out a level line or an even fall by eye. Paviors used them, and drainers found them indispensable. This is the size given in Baker's surveying textbook: 3 feet long, 3 inches wide, ½ inch thick, with a cross head about 6 inches long. Drainers usually made them longer. Source: T. Baker and F. E. Dixon, Land and Engineering Surveying, 23rd ed., Crosby Lockwood, London 1919, p. 106. The cross head's section, the fixing and the tools are ours. The picture shows boning rods set out for field drains (Alan Murray-Rust, CC BY-SA 2.0).