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Lot Essay
Robert Pennington, an eminent watchmaker, was working in London from about 1780 to his death in 1813. Pennington is believed to be the originator of the screw balance, of which this chronometer exhibits the earliest form. He is chiefly remembered as one of the finest horologists for his work with William Howells and others in producing at least 27 copies of Thomas Mudges's 'marine timekeepers' between 1794-1799, on behalf of the inventor's son and for whom he drew the excellent plates in A Description with Plates, published 1799.
It is significant, in the light of the only recently abandoned series of copies, that Pennington should have incorporated into his 1/430 certain features found in Mudge's timekeepers, but using the escapement (though with some modifications of his own) devised by Arnold, whom he considered a more capable horologist than Earnshaw (see Pennington's written submission concerning Arnold's and Earnshaw's Explanation to the Commission of Enquiry).
Unusually for an Arnold escapement, the discharging roller is beneath the impulse roller, an arrangment that is the opposite of Arnold's and more typical of an Earnshaw escapement.
The spring detent (see line drawing) and the mounting block assembly are very finely executed and probably unique in design. The detent is somewhat in the style of Breguet with a rectangular section cut out of the spring, between the root and the blade. Though the facility for depthing of the locking jewel and horn into the escapement for adjusting the 'lights' is not particularly unusual, the method of independently adjusting the depth of engagement of the passing spring and discharging jewel most certainly is.
With the exception of the balance cock endstone, the head of the securing screws for the jewel settings, or endstones where present, have a flat-filled edge to enable removal of the setting without completely undoing the screws.
The barrel assembly is identical to that fitted to Thomas Mudge Senior's No. 1, with the exception that in his chronometer the setting up of the mainsprings is by a worm and pinion, whereas Pennington employs a ratchet wheel and click. Two quite separate barrels operated within the outer brass casing or 'false barrel', and it is to this that the outer end of the fusee chain is hooked, in the usual manner. Each of these barrels has its own mainspring attached to the common arbor and these are wound in opposite directions - one clockwise and the other anti-clockwise - one being used to wind up the other. This arrangement gives the maximum output and the maximum number of turns of rotation of the barrel in the space available as it allows the full combined length of both mainsprings to be effective at the same time.
It is significant, in the light of the only recently abandoned series of copies, that Pennington should have incorporated into his 1/430 certain features found in Mudge's timekeepers, but using the escapement (though with some modifications of his own) devised by Arnold, whom he considered a more capable horologist than Earnshaw (see Pennington's written submission concerning Arnold's and Earnshaw's Explanation to the Commission of Enquiry).
Unusually for an Arnold escapement, the discharging roller is beneath the impulse roller, an arrangment that is the opposite of Arnold's and more typical of an Earnshaw escapement.
The spring detent (see line drawing) and the mounting block assembly are very finely executed and probably unique in design. The detent is somewhat in the style of Breguet with a rectangular section cut out of the spring, between the root and the blade. Though the facility for depthing of the locking jewel and horn into the escapement for adjusting the 'lights' is not particularly unusual, the method of independently adjusting the depth of engagement of the passing spring and discharging jewel most certainly is.
With the exception of the balance cock endstone, the head of the securing screws for the jewel settings, or endstones where present, have a flat-filled edge to enable removal of the setting without completely undoing the screws.
The barrel assembly is identical to that fitted to Thomas Mudge Senior's No. 1, with the exception that in his chronometer the setting up of the mainsprings is by a worm and pinion, whereas Pennington employs a ratchet wheel and click. Two quite separate barrels operated within the outer brass casing or 'false barrel', and it is to this that the outer end of the fusee chain is hooked, in the usual manner. Each of these barrels has its own mainspring attached to the common arbor and these are wound in opposite directions - one clockwise and the other anti-clockwise - one being used to wind up the other. This arrangement gives the maximum output and the maximum number of turns of rotation of the barrel in the space available as it allows the full combined length of both mainsprings to be effective at the same time.