English: Drawings of temperature-compensated marine chronometer balance wheels. These were designed during the 1st half of the 19th century by British chronometer makers attempting to improve on the standard Earnshaw balance, and win prizes at the British Admiralty Chronometer Trials. These are all attempts at solving the 'middle temperature problem'. An Earnshaw balance, when adjusted to keep time at high and low temperatures, gains as much as 4 seconds/day at middle temperatures from nonlinearity. The one on the right actually uses a tube of mercury for compensation. From Glasgow, David (1885), Watch and Clock Making, Cassell Co., p.247-256

Alterations to image: Collected five separate drawings from the book into one image