As the mean annual temperature of a country is, therefore, probably given by one year’s observations only, to within two or three degrees of the truth, the mean of a period of eight or ten years will, probably, come within one degree of the truth. By the comparison of the results of thermometrical observations, made in different countries, with each other, tracing the changes of temperature, which appear with certain changes of latitude or situation, some ingenious and philosophical men have endeavoured, by principles of analogy and induction, to determine the mean temperature of every parallel of latitude from the Equator to the north Pole. These calculations have been considered as near approximations; and, as long as observations were wanting, served for purposes of investigation, to complete the scale of the temperature of the globe. When we reach, however, the regions of perpetual ice, a remarkable anomaly is discovered, the mean temperature falling below the estimation in these tables at once 17°. From a series of observations on the temperature, etc., of the Polar regions, conducted with care during twelve successive voyages to the Greenland Seas, I am able to deduce the following conclusions. The mean temperature of the months of April, May, June, and July, are satisfactorily derived from the means of the latitudes and of the observations of temperature; but the mean temperature of the whole year, and of the winter months, wherein no observations in such high latitudes have yet been made, can only be ascertained by analogy. From the examination of numerous thermometrical registers, particularly one consisting of 54,750 observations, made in a succession of fifty years, at Stockholm, it would seem that the temperature of the year in northern latitudes is indicated by that of the 27th to 28th of April. I have collated 656 observations, made on 242 days, in nine different years, extending equally before and after the 27th of April, from which the mean temperature of the year, in latitude 76° 45′, near the meridian of London, appears to be 18° 86′. Reducing all the monthly temperatures derived from my observations to the parallel of latitude 78° north, by the application of Mayer’s formula, and allowing for the fact that many of the observations of April were made at a considerable distance from the ice, I calculate the temperature of April, latitude 78°, to be 14° 23′, and the mean of the year in the same proportion exactly 17°. Having discovered, by observation chiefly, the mean temperature of the months of April, May, June, and July, and the probable mean temperature of the year in the icy regions adjoining Spitzbergen, I conceive it not difficult to calculate the temperature of the remaining months. The difference between the mean temperature of the year and that of July, is 21½° in Stockholm, and 20° near Spitzbergen. Finding not only that the difference of temperature between the mean of the year and July, near Spitzbergen, but that