death_date death_place children birth_place image_size birth_date image article_title name occupation
11 august 1799 eltham , kent , england john roger bodmin , cornwall , england 160px 1736 john_arnold . jpg john arnold -lrb- watchmaker -rrb-
 john arnold watchmaker
john arnold -lrb- watchmaker -rrb-

john arnold -lrb- born 1736 probably in bodmin , cornwall -- died 1799 in london -rrb- was an english watchmaker and inventor .
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 chronometers 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 .
it is necessary to point out that the brand name `` arnold & son '' used by a swiss watch company has absolutely no connection to the original firm founded by john arnold .
it was from around 1770 that arnold developed the portable precision timekeeper , almost from the point where john harrison ended his work in this field .
but compared to harrison 's complicated and expensive watch , arnold 's basic design was simple whilst consistently accurate and mechanically reliable .
importantly , the relatively simple and conventional design of his movement facilitated its production in quantity at a reasonable price whilst also enabling easier maintenance and adjustment .
but three elements were necessary for this achievement : a detached escapement , which gave minimal interference with the vibrating balance and balance spring a balance design that enabled compensation for the effect of temperature on the balance spring a method for adjusting the balance spring , so that the balance oscillates in equal time periods , even through different degrees of balance arc
