Swiss yellow gold chronograph with tachometer Circa 1907

Gold open faced keyless lever
–
A Swiss 18 Carat yellow gold keyless pocket watch, circa 1907. With a co axial single-button chronograph, 15 minute register and tachometer. A solid, polished case, hinged gold cuvette engraved with miniature medals, and chronograph button co axial to the winding crown. Two-tone white enamel dial with bold Paris numerals, outer Arabic seconds, minute/seconds and 1/5th seconds chronograph divisions, sunk subsidiary dials for the constant seconds and 15-minute register, outermost spiral tachometer graduation scale and black oxidized gold spade hands.
–
A frosted gilt movement, 3/4-plate, 15 jewels, straight-line lever escapement, cut bimetallic compensation balance with Breguet balance spring, index regulator, the chronograph work is set on a separate plate fastened to the back plate. Case, dial and movement signed. This watch is sold with a box and certificate of authenticity.
–
Diameter: 50 mm
–
Signed: Omega  Swiss