Note 25 — PHILOSOPHICAL JOURNAL. (continued 2)

From Mr Glaisher's Hygrometrical Tables, the accuracy of which my own series of observations made in the years 1847 and 1848, for the purpose of testing their correctness, shew in a very striking manner; and I think every meteorologist must feel himself greatly indebted to Mr Glaisher for this valuable compilation, which is also based on observations made under his own superintendence at the National Observatory. In eight months of the year 1847, the difference between the observed and the deduced Dew-point at Whitehaven, is 0°·10; and in 1848, it is only 0°·07, the mean of the two periods comprising 1220 observations, amounting to the comparatively evanescent fraction of 8/100ths of a degree. Such satisfactory proofs of the perfection of Mr G.'s tables have induced me to abandon Daniell's Dew-point Apparatus, for that more simple, less costly, and equally correct form of Hygrometer, the combination of the dry and wet bulb thermometers.