Awhile back, we had a thread about the original references for proportions for Catskill-style flies. I believe the earliest anyone knew of was back in the 1940s? I tried to find the thread but couldn't.

Anyway, I downloaded the 1919 edition of H.G. McClelland's The Trout Fly Dresser's Cabinet of Devices, which according to Mike Valla, was one of the original learnings tools for both the Dettes and the Darbees.

McClelland calls for the wing of a mayfly dun and spinner to be as long as the head, thorax, and abdomen (the shank), with the tail of the dun to be in a ratio of 7:6 to the shank. For a spinner, McClelland says the tail should be in a 7:4 ratio to the shank.

The book was originally written in the 1890s I believe, so these proportions may have been printed then.

-Steven