John Arnold rapidly established a reputation for
outstanding mechanical expertise and was the first watchmaker to
produce a jewelled ruby cylinder escapement, which he showcased in
an exceptionally small half-quarter repeating watch mounted in a
ring and offered to King George III.
His growing fame attracted an affluent clientele. He could
easily have lived comfortably, making exquisite repeating watches
and calendar watches. But John Arnold was relentlessly driven by
the greatest watchmaking challenge of his age: to build a timepiece
that would enable ships to navigate safely, transform science and
roll back the boundaries in astronomy. That challenge was
precision, and Arnold made it his passion.
Between 1770 and 1790, he painstakingly refined the art of
watchmaking, introducing decisive improvements that heralded the
arrival of chronometry. It is to him we owe a series of
trailblazing inventions that included a detentescapement, a helical
balance spring, terminal curves that make the helical balance
spring isochronal, the first-ever use of gold for balance springs,
and a range of bimetallic balances that offset errors caused by
Arnold's chronometers were used by some of the greatest
explorers and navigators of his age on their epic voyages. His
regulators and their continual refinement bear witness to the
colossal progress of science and astronomy across Europe.
Arnold was also heir to a series of exceptional English
watchmakers, each of whom advanced the art of watchmaking in his
own way: George Graham, Thomas Tompion, Thomas Mudge and John
Harrison. Arnold, however, was the first to usher watchmaking into
the modern era by designing high-precision, reliable watches that
were also relatively easy to manufacture. In its report on Arnold's
pocket chronometer No. 2 in 1780, the Board of Longitude had this
"So far as this watch has been tried, it must be acknowledged by
all, that it is superior to every one that had been made before it.
Nothing therefore seems to remain but for … Mr. Arnold … to make
other watches … to entitle him to the second reward offered by
Parliament for improvements in this branch of mechanics, and also
to the universal approbation and applause of his fellow-citizens."
2 The Monthly Review or Literary Journal,vol.58