English chronograph with rare central min register Circa 1860

Gold open faced lever chronograph by Dent
–
An unusual English 18 carat gold open faced keyless lever chronograph watch with regulator dial and rare central minute register, circa 1860. 3/4 Plate gilt finished lever movement, bimetallic compensation balance. White enamel dial, two sunken subsidiary dials for hours and constant seconds, outer calibrated 1/5th seconds ring for the chronograph with central hands for the minutes and minute register. Plain case, snap on back. Dial and movement signed and numbered, case stamped with casemaker’s initials AN for Adolph Nicole.
–
Diameter: 52 mm
–
Signed: Dent 33 Cockspur Street London Watch Maker to the Queen