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 instrument he described in a work entitled: "Phoronomia," published at Amsterdam in 1716. This instrument showed directly the elasticity of the confined air, and thereby the temperature, a correction being made for the temperature of the column of mercury.

Frequent allusions to the thermometer of Philippe de la Hire are met with in works on meteorology, and his instrument was famous not because of its novel construction, but owing to the long series of observations conducted with it and published in the Memoirs of the Academy of Sciences, beginning with the year 1670. It was a Florentine thermometer having a scale the value of which has never been accurately determined; La Hire considered it sufficient to state that it had two fixed points, the temperature of a deep cellar in the observatory (48°) and that of the air in an open room when it was freezing in the vicinity.

Amontons sought to compare his standard thermometer with that of La Hire, but could not obtain permission from the authorities to place his instrument alongside of it in the observatory; after his death a superficial comparison was made. Lambert says the zero of La Hire's scale was the temperature of a