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 advance on the baro-thermoscopes that had preceded them, but their graduation left much to be desired; those of different lengths had degrees of unequal value, and individual instruments of the same pattern gave results only approximately similar. Their agreement depended on the skill of the workmen, who sought to get comparable thermometers by taking care to get tubes and bulbs equal in size, but they had no standard of graduation.

Florentine thermometers, made by skilful workmen, became famous throughout Europe; together with Torricelli's barometer and Ferdinand II's hygrometer, they were used at meteorological stations established by the Grand Duke, and conducted in Florence by Raineri, in Pisa by Borelli, as well as in Bologna, Parma, Milan, Warsaw, and Innsbruck; the instruments were observed several times daily and records were kept with great fidelity. One of the Italian day-books containing sixteen years' observations was examined by Libri in 1830, and he obtained evidence that the climate of Tuscany had not materially changed.

The meteorological observations made in Florence from December 15, 1654, to March 31, 1670, were published entire in the