拍品專文
The Hartnup balance, unique in design and construction, was invented by John Hartnup, the Liverpool Observatory's first director, appointed 1843. As distinct from the Chronometer Department at Greenwich, primarily concerned with rating and purchase of chronometers for Government service, one of Hartnup's chief tasks was the rating of chronometers for merchant ships and he soon became concerned with the problem of 'middle temperature error'. The Liverpool maker, William Shepherd, made the prototype of Hartnup's balance circa 1847. After very successful trials at Liverpool and at the suggestion of his friend, the Revd. Richard Sheepshanks, editor of the monthly Notices of the Royal Astronomical Society, Hartnup contacted Airy, the Astonomer Royal, at Greenwich. Three Shepherd chronometers with Hartnup's balance were tried there in 1848. The Greenwich trials were not as favourable as those at Liverpool and Hartnup then questioned the mode of testing at Greenwich. The inventor himself had not intended to gain by patenting the balance but by his own admission it took at least twice the labour to make as an ordinary balance. As confirmed by Gould, it was never generally used, and therefore extant examples are rare.
Robert Walshaw is recorded as a watch, chronometer and nautical instrument manufacturer, at 178 Park Lane, Liverpool from 1860 to 1864, whereafter the business moved to 91A Pitt Street. (We acknowledge our thanks to Prescot Museum for this information).
Robert Walshaw is recorded as a watch, chronometer and nautical instrument manufacturer, at 178 Park Lane, Liverpool from 1860 to 1864, whereafter the business moved to 91A Pitt Street. (We acknowledge our thanks to Prescot Museum for this information).