Compass secret orifices in “The Complete Book of Five Secret Apertures” Gan Shi looked at

ternary compass solution

Compass Explanation Page 415

Ye Jiusheng’s compass to clear the fog (ancient version).pdf

Compass decomposition and use classics (manuscript without watermark).pdf 77 pages

Newly ordered Wang’s compass, 2 volumes, compiled by Wang Daoheng, corrected by Wang Shaozhi

A newly engraved thimble of the compass in Xu’s family collection

Compass knowing set.pdf

A newly engraved thimble of the compass in Xu’s family collection