The early portion of last summer was remarkably cold while the autumn has been quite mild. It is generally the case, that unusual coldness or heat in one portion of a season is compensated for at another period. There has never, within our recollection, been but one summer in which the general temperature throughout exhibited a marked difference from that ordinarily experienced. This was in 1836, and was probably caused by the large spots on the sun which were visible to the naked eye. These large dark spots would seem to have detracted temporarily from the heating power of the sun. Heat is continually radiated from the earth into space, and as continually received from the sun. In case the supply be in the least diminished, the radiation lowers the temperature. It was a great omission in Byron's terrific dream of darkness, not to allude to the marked degree of cold which would follow from the total absence of the sun, even for a single day. Although the solar rays have an immensely preponderating influence over all other causes in controlling the terrestial heat, there are influences somewhat mysterious which affect the subject. If we trace on the map of our country the lines of equal temperature, they will differ very widely from the parallels of latitude. The mild winter temperature of North Carolina, for example, is imitated by Texas which is some three degrees further south, and by Washington Territory which is seven degrees further north. The winters of Delaware are similar to those of central Indiana, one degree further north, those of Missouri and southern Kansas, a trifle farther south, and those on Puget's Sound in the extreme north of Oregon, a locality nearer the North Pole than freezing Quebec. There are local causes due to the influence of prevailing wind, etc., which greatly affect the temperature of a country. The warmth on the Pacific coast is due to warm ocean currents, and the temperature of the British Islands, France and Spain, is materially affected by this influence, in consequence of the Gulf Stream, which, commencing in a warm latitude, flows across the ocean, avoiding our coast, and impinging directly on the shores of Europe. There is supposed to be an influence due to the lines of magnetic variation, though it may reasonably be doubted whether the variations in magnetic influences should not be considered as the effect of the differences in heat. Bones of elephants, and of the tropical animals, have been found among the icebergs of Greenland, and although this might be explained by supposing the temperature of the whole earth to have been once greater than at present, in consequence of internal heat possessed at creation, and that the polar regions first became habitable only for animals adapted to a very warm climate, the question is rendered extremely complex by the discovery in soft and balmy Italy of remains positively known to be those of animals now inhabiting only the mountains of Siberia. But we are no believers in the igneous theory, and consequently ascribe this to the precession of the Equinoxes, which causes a gradual change in the position of the magnetic meridian. It is difficult to explain these phenomena by a supposition that the character and habits of the animal races have changed, and we must believe that the temperature of various localities has undergone, at various times, immensely great changes, and that such may be now gradually progressing. The climate of New England is thought by many to be much milder than in the days of our forefathers, although we are of the opinion that the I records which have been kept of its temperature do not show such changes to be at all important, but there are traditions of a much R warmer climate, being once enjoyed by the k whole of our northern continent. The subject /) is certainly one of great interest.
This article was originally published with the title "The Distribution of Heat" in Scientific American 13, 12, 91 (November 1857)