B65-645 BITSTOCK. Darling Patent Variation. These braces turn up occasionally, and have a chuck mechanism that is very similar to Darling's 1868 patent, one of the rarest and most collectible of the patented braces (see Lot 107) except that instead of a spring it has a knob to tighten the jaws. Like the original Darling design, it's never marked, and is generally considered a later variation on the Darling patent. From the collection of Jim and Christa Schoenky. Fine 200-400