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Page:Popular Science Monthly Volume 32.djvu/588

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THE POPULAR SCIENCE MONTHLY.

teorite and meteorite. At this point the direct evidence of the spectroscope fails us. The force of gravity which has drawn the meteorites gradually together must still continue to operate, but as its operations become more intense the collisions will become more frequent, until at last the meteorites are completely volatilized by the heat evolved, and in that case the star becomes a mass of incandescent vapor at a transcendental temperature. We know that such stars exist, but we can not produce their spectra in the laboratory because we have no means of obtaining the temperature required. The condensation is now complete, and the highest temperature capable of being evolved by the forces at work has been attained. When gravity has resulted in the complete volatilization of the gravitating bodies its power is exhausted, and the process of cooling must thenceforth set in. This stage is exhibited in the stars of Class II, of which our sun is the most familiar example. The stars in Vogel's Class IIIb once more exhibit spectra capable of approximate reproduction in the laboratory, and thus show that they have returned to a temperature no longer transcendental. The last stage of all is that of stars, or bodies associated with the stars, so cool as no longer to be incandescent. The spectroscope tells us nothing of them, but there are good evidences of their existence. Is this the end? We can not say so with any confidence. We have no right to say that collisions can not occur between the larger bodies as well as between the meteorites. Then "the cycle of the universe would be complete, and we might say of the Cosmos as the geologist Hutton said of the earth—that it exhibited no trace of a beginning, and no evidence of an end. This, however, is pure speculation."

 

Antiquity of North American Flora.—Reasons are adduced by Mr. A. T. Drummond, in his discussion of the distribution of British North American plants, for supposing that America was the starting-point of that phase of the vegetation which, in its later development, has become the flora of to-day. The first undoubted evidences of this flora, on any considerable scale, are found in the Leda clays of the Ottawa Valley. The Eocene flora resembles, not so much the Eocene as the later Miocene of Europe. Seeing that the Eocene and Upper Cretaceous of North America, in the resemblance of their flora to that of northern temperate America of to-day, are older than the European Cretaceous and Eocene, that it was only in later epochs in Europe that the generic identity with North American plants became so very distinctly marked, and that in Europe many of the genera of the Pliocene identical with those of to-day have since become extinct, "there seems a possible presumption," says the author, "quite apart from that derivable from their present range, that some of these identical European and American plants may be older in America, and being northern temperate in range may have originated in northern temperate America."

 

The Peabody Museum.—The latest—the twentieth—annual report of the Peabody Museum of American Archaeology and Ethnology records the complete affiliation of that institution with Harvard University by the installation of its curator, Dr. F. W. Putnam, as professor there. This position imposes no duties which the curator of the museum has not already performed, they consisting only of the delivery of one or more courses of lectures annually; but it brings the museum more closely into the general system of the university. The archaeological work which the museum has in hand includes explorations in Nicaragua and Costa Rica through the co-operation of Dr. Earl Flint, in the course of which many relics, including some of jade, have been recovered, and human foot-prints have been found in volcanic tufa sixteen feet below the surface; continued explorations by Dr. C. C. Abbott, in New Jersey, which have yielded, in fragments of human skeletons associated with the stone implements in the glacial gravel, the earliest record of man on the Atlantic coast; the explorations of the shell-heaps of Maine, under Dr. Putnam's personal supervision, which have brought to light many interesting facts relative to the early occupation of New England by man; the ethnological researches of Miss Alice C. Fletcher among the Omaha and Sioux Indians, which is growing into a his-