English important and rare pocket chronometer Circa 1818

Silver chronometer with Arnold’s right angle compensation
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An important and extremely rare pocket chronometer with Arnold’s right angle compensation made by John R. Arnold in London, England, circa 1818. Encased in a typical plain silver open faced case, hinged on both sides, with London Hallmarks from 1818, maker’s mark TH for Thomas Hardy and the number 3022. The white enamel dial features Roman numerals for the hours, an outer minute track, a subsidiary dial at 6 o’clock with Arabic numerals for the seconds and gold spade hands.
What sets this chronometer apart is its extremely rare right angle compensation regulation. The movement is magnificently engraved on the cock and features a steel balance wheel. Dial and movement are signed and numbered, adding to the authenticity and rarity of this pocket chronometer.
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Diameter: 58 mm
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Weight: 150 g
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Signed: Jn R Arnold London
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John Roger Arnold
John Roger Arnold was born in 1769. He was the son of renowned British horologist John Arnold. He served an apprenticeship with both his father in 1783 and the eminent French watchmaker Abraham-Louis Breguet in Paris in 1792. In 1787, John Roger and his father founded the company, Arnold & Son. The younger Arnold became a member of the Clockmakers’ Company in 1796 and became a master in 1817. After his father died in 1799, he continued the business, taking up a partnership with E.J. Dent in 1830. The two craftsmen experimented heavily during their work together, in particular, they concentrated on the effects of magnetism on chronometers. Dent left Arnold in 1840, whereupon Arnold continued working on his own but died only three years later. Charles Frodsham bought the business after Arnold’s death in February 1843 and it flourished until 1858 under the name Arnold & Frodsham.
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Arnold escapement
It is rare to find an unconverted Arnold escapement. It is even rarer to find one with such unusual compensation. In a regular compensation curb, all parts are fixed and are installed as such, they cannot be adjusted, so they either work correctly or not. In this watch, the compensation can be adjusted by changing the point at which it acts on the regulator pin: the closer to the center, the greater the compensation, the farther away, the lesser the compensation. It seems that the present compensation was Arnold’s answer to Earnshaw’s sugar tong compensation.
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Right angle compensation
Right angle compensation is a mechanism used in watchmaking to counteract the effects of gravity on the balance wheel. The balance wheel is an essential component of a mechanical watch that oscillates back and forth to regulate the timekeeping. However, due to the position of the watch, the balance wheel is affected by the force of gravity, which can cause the watch to run either fast or slow. Right angle compensation works by adjusting the position of the hairspring, which is attached to the balance wheel. By changing the position of the hairspring, the watchmaker can compensate for the effects of gravity on the balance wheel. This is achieved by making the hairspring perpendicular to the balance wheel when the watch is in a vertical position.