In my reading about chronometers and observatory timekeeping I've now more than once come across mentions of a curious instrument that's alternatively called a chronometrical thermometer or thermometric chronometer. Gardner, Henry Dent. 1890. "The ship's chronometer, its history and development." The Journal of the Royal United Service Institution, Vol. XXXIV, No. 151, pp. 313-338. Leuschner, A.O. 1891. "On the thermometric chronometer of the Lick Observatory." Publications of the Astronomical Society of the Pacific, Vol. 3, pp. 177-180. If you look at the Greenwich chronometer trials results from 1841/42 to 1915, you can see that the data tables record the weekly rates for the chronometrical thermometer along with the timepieces under trial. This tells us that the instrument was in use as early as 1841. Gardner's article, when it touches on the Greenwich trials, describes it (page 327): Leuschner's description (p. 177): Gardner says that Greenwich's instrument was compensated "the wrong way"; Leuschner says Lick's instrument was "uncompensated." I don't think it's clear whether the instruments were different or just the descriptions. Why would one want a chronometer that magnifies temperature fluctuations? Gardner tells us a bit about it (p. 327 again): Or in more mathematical terms, if we model temperature as a function of time, the chronometrical thermometer is indirectly measuring the integral of that function. So now, my question: has any of you seen anything like this out in the wild? So far it sounds like the thing to look for is a box chronometer where the balance is either: Obviously not compensated; Has a "compensation" whose design appears to be backwards.