Grasshopper escapement it in his prototype marine chronometers, H1 - H3, and Justin and Benjamin Vulliamy made a small number of regulators using Harrison's design, but generally it remains today what it was in Harrison's time: a brilliant, unique curiosity. A unique public clock built as a tribute to John Harrison's grasshopper escapement, the Corpus Clock, was unveiled at Corpus Christi College, Cambridge University, in Cambridge, England on 19 September 2008. Industrialist John Taylor spent £1 million building the mechanical clock. Feeling that Harrison's escapement was not well enough known, the clock's grasshopper escapement is exposed on the top of the clock,
Escapement was unworkable. Arnold also designed a spring detent escapement but, with improved design, Earnshaw's version eventually prevailed as the basic idea underwent several minor modifications during the last decade of the 18th century. The final form appeared around 1800, and this design was used until mechanical chronometers became obsolete in the 1970s. The detent is a detached escapement; it allows the balance wheel to swing undisturbed during most of its cycle, except the brief impulse period, which is only given once per cycle (every other swing). Because the driving escape wheel tooth moves almost parallel to the pallet, the escapement