Found this one in a junk pile and had it fixed. I had never found one with a key like this before. The key folds down and stays with the watch.

Greg

Nice find! Even 'common' watches sometimes show something unusual.

US Patent 189600 by William H. Bracy of Boston, Ma

...a device which of itself forms a portion of the watch and dispenses with the neccessity of a seperate key...

Regards,
Gerald

Correct me if I'm wrong but those days the watches were cased by the jeweler so I think this was a special add offered and fitted at a jeweler's shop where movement and case met the first time.

Gerald

Greg,
Nice looking mdl. 57, and with a scarce add on to boot.