A VICTORIAN LACQUERED BRASS PORTABLE TIMPIECE WITH UNUSUAL CHRONOMETER-TYPE DETACHED ESCAPEMENT

A VICTORIAN LACQUERED BRASS PORTABLE TIMPIECE WITH UNUSUAL CHRONOMETER-TYPE DETACHED ESCAPEMENTUNSIGNED, MID 19th CENTURYThe circular four ring-turned columnar pillar single fusee movement with Harrison-type maintaining power and six-spoke wheel crossings to all except the escape wheel, the unusual twin-arbor detached escapement with impulse provided via the balance arbor and locking/unlocking enabled via a pallet applied to a second arbor, controlled by a detent tripped by a discharging flag set beneath the impulse pallet, regulated by sprung three-arm monometallic balance with steel screw timing weights, the backplate with balance cock incorporating faceted diamond endstone, F/S regulation lever and sub plate for the escapement locking pallet arbor top pivot and cone-tipped depth adjustment screw, with a 3.25 inch slightly convex white enamel Roman numeral dial with blued steel spade hands, in a cylindrical brass case with finely moulded bayonet fitting convex glazed cast brass bezel applied to the drum engraved with O/S for 'open' and 'shut' positions at the junction between the two, with a suspension post and ring at twelve o'clock and the rear with press-on slightly convex cover incorporating fine moulded outer edge and shuttered winding hole, (evidence of some alteration).The movement 7.4cm (2.875ins) diameter, the case 9cm (3.5ins) diameter, 4.5cm (1.75ins) deep. The escapement fitted to the present timepiece differs from the standard form of sprung detent chronometer escapement in that the locking pallet is applied to a separate second arbor rather than a detent spring. The action of the locking pallet is controlled by a long needle-like lever fixed to its arbor, with the opposing end engaging with the discharging flag fitted to the balance arbor (beneath the impulse pallet). The rotation of the second pallet arbor is controlled by a small spring so that the locking pallet returns to its resting position, ready to lock the escape wheel, immediately after releasing.The movement plates have a few spare holes indicating that some alteration may have taken place however the escapement is very well executed and appears most likely contemporary with the rest of the mechanism. It is not unusual to see some spare holes/adjustments in the plates of semi-experimental timepieces, as these were often made for mounting/testing on a bench with casing-up often seen as an after-thought. Notwithstanding this the case is of notably solid construction with nicely executed details such as the fine mouldings to the outer edges. Condition Report: Movement is in clean working condition. The trains would suggest a duration of 1-2 days. As catalogued the movement plates have some spare holes so exhibit evidence of possible alteration/re-thinking however this evidence does not suggest that the timepiece has been adapted from another known type. Indeed it would appear that the movement is a one-off and experimental in nature. Dial is free form visible damage/restoration and the case is also in fine original condition.There is no winding key present with the present lot.Condition Report Disclaimer