Scientific Serials

Abstract

American Journal of Science, November.—On the relative motion of the earth and luminiferous ether, by Albert A. Michelson and Edward W. Morley. A complete and satisfactory explanation of the aberration of light is given by Fresnel's undulatory theory, which assumes, first, that the ether is supposed to be at rest except in the interior of transparent media; secondly, that in this case it moves with a velocity less than that of the medium in the ratio??? where n is the index of refraction. The second hypothesis having been fully established by Fizeau's celebrated experiment, the first alone is dealt with in this paper. From the delicate researches here described, which have been carried out by the aid of the Bache Fund, it is inferred that, if there be any relative motion between the earth and the luminiferous ether, it must be small, quite small enough entirely to refute Fresnel's explanation of aberration. It is further shown that the theories of Stokes and Fresnel also fail, and that it would be hopeless to attempt to solve the question of the motion of the solar system by observations of optical phenomena at the surface of the earth.—On the existence of carbon in the sun: contributions from the physical laboratory of Harvard University, by John Trowbridge and C. C. Hutchins. Without discussing the well-known observations of Abney on the absorption-bands in the solar spectrum at high altitudes, or Siemens's hypothesis of the presence of carbon vapour in interplanetary space, the authors here study the remarkable character of the carbon spectrum formed by the voltaic arc in air between carbon terminals, drawing attention to the evidence presented by the juxtaposed solar spectrum of the existence of carbon in the sun. They conclude that at the point of the sun's atmosphere where the carbon is volatilized, the temperature of the sun approximates to that of the voltaic arc.—History of the changes in the Mount Loa craters, by James D. Dana. A recent visit of ten weeks to Hawaii has enabled the author to carry out the purpose expressed in his communication of last August. Here are presented only such facts as bear on the history of Kilauea since 1832, the general summary and conclusions being reserved for future numbers of the journal. The subject is illustrated with plates of Kilauea Crater, its lava floor, and the Halema'uma'u basin.—Is there a Huronian Group? (continued), by R. D. Irving. For the extensive region stretching from the north side of Lake Huron to the Mississippi it is here concluded that the succession of rocks in ascending order is from the great complex of crystalline schists, gneiss, and granite through the Huronian Group, mainly of detrital rocks, to the Keweenaw, of interleaved detrital and eruptive beds and the Potsdam, or Upper Cambrian Sandstone, with great structural breaks between the first and second, and second and third groups. The Huronian series itself, traceable throughout the Lake Superior province, is shown to be of clastic and sedimentary nature, of great volume, and structurally and chronologically separated from all other rock formations. The term Agnotozoic, originally suggested by Chamberlain, is proposed to cover the whole geological interval lying between the base of the Cambrian and the summit of the Archæan crystallines,—Description of an iron meteorite from St. Croix, County Wisconsin, by Davenport Fisher. This specimen, discovered in 1884 on a farm in Hammond Township, weighed 53 pounds, and yielded, on analysis: iron 89.78, nickel 7.655, cobalt 1.325, phosphorus.512, silica 562, with traces of carbon, copper, and tin.—The Rockwood meteorite, by J. Edward Whitfield. Picked up in March 1887 in a field in Cumberland County, Tennessee, this meteorite yielded, on analysis: iron 87.59, nickel 12.09, with traces of cobalt and copper.—Principal characters of American Jurassic Dinosaurs, by O. C. Marsh. This paper, forming Part 9 of the whole series, deals with the skull and dermal armour of Stego-aurus, a nearly complete skeleton of which has lately been discovered. The specimen here described constitutes a new and very distinct species, for which the name of S. duplex is proposed.