US Patent 2,080,771 by Frank Corbyn Hale, assigned to Celanese Corporation of America, describes a shedding mechanism that weaves doup selvedges in circular looms. Pairs of warp threads cross over each other at every pick so the tubular fabric can be split lengthwise without the edges unravelling. The text covers the combs with eyed and long dents, the cam and spring that move the comb, shedding wheels and stops, and 10 claims, with one drawing sheet showing Figures 1 to 6.