That's an interesting patent. I've heard it said that George used a three strand loom. But not by those drawings--which clearly illustrate a two-strand loom.
Pott used a two strand loom as well. And Pott patented his flies in 1931, seven years prior to Grant's application:
http://montana-riverboats.com/index....Patent-Diagram
Pott's patent diagram doesn't show how many weaving strands are used. But Pott did use a two-strand loom. So this does bring up an interesting nit-pick question. If George Grant also got a patent for woven hair hackles, also using a two-strand loom, something about Grant's technique had to be different. Else the patent was issued in error. Perhaps it was the knotting procedure.