A very rare mid 19th Century tic-tac escapement alarm in a nickle drum case. Unusual full plate brass movement with a single barrel powering both the alarm and going trains. Plain cock with blue steel coqueret, plain three arm steel balance with blue steel spiral hairspring set in a circular aperture in the plate. Very rare tic-tac escapement where the English lever escape wheel acts directly on a polished steel roller on the balance staff. The tooth of the escape wheel rests on the roller for most of the vibration, giving impulse only in one direction as a slot in it passes. Single hammer for the alarm striking on the side of the case which acts as a rudimentary bell. Silvered dial with black waxed Roman numerals. Central alarm disk with waxed pointer, thumb piece at the back for adjustment. Single blue steel hand for the hours only. Nickle drum case with fixed glass. Outer morocco slip travelling case, the top apparently lost.