The statement so often repeated, although unsupported by any thermometric measurements, that since the first European settlements in New England, Pennsylvania, and Virginia, the eradication of many forests on both sides of the Alleghanies had rendered the climate more equable, (_i. e._, milder in winter and cooler in summer), is now generally doubted or disbelieved. Series of trustworthy thermometric observations in the United States hardly extend so far back as 78 years. We see in the Philadelphia observations, that from 1771 to 1824, the mean annual temperature has hardly increased 1°.2 Reaumur, (or 2°.8 Fahrenheit),--a difference which is attributed to the increased size of the town, to its greater population, and to the numerous steam-engines. The difference may possibly be merely accidental, for I find in the same period an increase of mean winter cold, amounting to 0°.9 Reaumur, or 2° Fahrenheit; the three other seasons had become somewhat warmer. Three-and-thirty years’ observations at Salem in Massachusetts shew no alteration at all: the annual means oscillate, within a degree of Fahrenheit, about the mean of the whole number of years; and the winters of Salem, instead of having become milder, as supposed from the destruction of the forests in the course of the thirty-three years, have become colder by 1°.8 Reaumur, or 4° Fahrenheit. (Forry, p. 97, 101, and 107.) As the east coast of the United States is comparable in respect to mean annual temperature in equal latitudes to the Siberian and Chinese coasts of the old continent, so also the west coasts of Europe and America have been very properly compared together. I will only take a few examples from the western region on the shores of the Pacific, for two of which (Sitka in Russian America, and Fort George, in the same latitudes respectively as Gottenburg and Geneva) I am indebted to Admiral Lütke’s voyage of circumnavigation. Iluluk and Danzig are nearly on the same parallel, and although the mean temperature of Iluluk, owing to its insular climate and to a cold sea-current, is somewhat lower than that of Danzig, yet the winter temperature of the American station is milder than that of the port on the Baltic.