拍品专文
This chronometer was placed "first" at the 1879 Greenwich Observatory Annual Chronometer Trials. In the specifications for these trials, under the heading "Construction of Escapement and Blanace" David Keys states - "Ordindary balance with slight alteration. Airy's Compensation". The bi-metallic rim has an affix at the joining point of the rim and the cross-arm which strongly resembles Poole's auxiliary, in addition it has two blued steel springs, one attached to each part of the Poole auxiliary which bridges the cut-gaps in the balance rim, each spring bearing against and controlling the movement of each bi-metallic sector at its outer end. The Airy's Compensation is no longer extent. The Greenwich Observatory Digest Book would appear to indicate that this was removed in 1885. The auxiliary fitted to this chronometer is not recorded in Gould, however a number of the chronometers exhibited by David Keys in the Greenwich Chronometer Trial are also described as "Ordinary balance, with slight attention" so it must be assumed that this is his own auxiliary.