JOHN ARNOLD

JOHN ARNOLD Watches

John Arnold was the first to design a watch that was both practical and accurate, and also brought the term "Chronometer" into use in its modern sense, meaning a precision timekeeper. His technical advances enabled the quantity production of Marine Chronomete

rs for use on board ships from around 1782. The basic design of these, with a few modifications unchanged until the late twentieth century. With regard to his legacy one can say that both he and Abraham-Louis Breguet largely invented the modern mechanical watch. Certainly one of his most important inventions, the Overcoil balance spring is still to be found in most mechanical wrist watches to this day.

HISTORY

John Arnold was apprenticed to his father, also a clockmaker, in Bodmin. He probably also worked with his uncle, a gunsmith. Around 1755, when he was 19, he left England and worked as a watchmaker in the Hague, Holland, returning to England around 1757.[1]

In 1762, whilst at St Albans, Hertfordshire, he encountered William McGuire for whom he repaired a repeating watch. Arnold made a sufficient impression so that McGuire gave him a loan, enabling him to set up in business as a watchmaker at Devereux Court, Strand, and London. In 1764, Arnold obtained permission to present to King George III an exceptionally small half quarter repeating watch cylinder escapement watch mounted in a ring. A similar repeating watch by Arnold has survived; it is of interest that the basic movement is Swiss in origin but finished in London. The escapement of this watch was later fitted with one of the first jeweled cylinders made of ruby.

Arnold made another watch for the King around 1768,[2] which was a gold and enamel pair cased watch with a movement that had every refinement, including minute repetition and centre seconds motion. In addition, Arnold fitted bi-metallic temperature compensation, and not only was every pivot hole jeweled but the escapement also had a stone cylinder made of ruby or sapphire. This watch Arnold designated "Number 1" as he did with all watches he made that he regarded as significant, these numbering twenty in all.

BRIEF DESRIPTION

Arnold's approach to precision timekeeping was completely different from that of Harrison whose technical ethos was rooted in seventeenth and early eighteenth century theory and practice. Arnold knew that as the balance and balance spring control the timekeeping in a portable watch, he only needed to find a way of giving the balance a consistent impulse with minimal interference from the wheel work, together with effective temperature compensation. After making some experimental machines, he produced what could be regarded as a production model to the Board of Longitude in March 1771.

This machine was completely different from Harrison's watch. It was a mahogany box of approximately 6 x 6 x 3 inches that housed a movement that, though relatively simple, was close to the same size as Harrison's, with a balance of a similar diameter. The radical difference, however, was a newly designed escapement that featured a horizontally placed pivoted detent that allowed the balance to vibrate freely, except when impulsed by the escape wheel. The spiral balance spring also had a temperature compensation device similar to those in Arnold's watches, and based on Harrison's bimetallic strip of brass and steel. Arnold proposed manufacture of these timekeepers at 60 guineas each

PRODUCTS

Company	Model	Model
John Arnold	45A120	45A121