A rare silver keyless mystery watch, Armand Schwob & frère, 'Mystérieuse', no. 3011 circa 1890

crescent-shaped frosted gilt cylinder escapement , flat rimmed three arm balance, hands moved by rotating glass discs with Roman numerals, outer minute track, silver case glazed on both sides, engine turning to the cuvette, cuvette signed A.S. & F. and numbered 3445.