Page:Evolution of the thermometer.djvu/54

 air in the bulb expanded, it pressed upon the column of water which in turn forced the mercury up the shorter and wider tube. Hubin claimed for this instrument greater delicacy than the Florentine in the proportion of 216 to 4, as determined by experiment.

The question, who first used quicksilver as the dilating liquid in thermometers, is apparently a simple one, to be easily answered, but like many other questions of priority in the history of the thermometer, many claims have been advanced and the problem requires examination; no less than ten names are mentioned by different authorities as inventors of mercury thermometers. Thermometers containing mercury were indeed made at an early date, but the liquid metal was only an accessory to the air-thermoscope and was not used as a heat-measurer.

Athanasius Kircher, in 1643, mentions a thermoscope containing mercury, but does not describe the function of the liquid metal. The Accademia del Cimento, as related in the diary of the society, made mercury thermometers in 1657, compared them with water-thermometers of the same size, and observed that the former fell and rose more quickly than the latter when