Scientific Serials

Abstract

American Journal of Science and Arts, December 1873.—In a paper on the magnetic permeability (that is “conductivity,” according to Faraday), and the maximum of magnetism of iron, steel, and nickel, by Mr. Henry Rowland, C.E., the results are expressed, and the reasoning is carried out in the language of Faraday's lines of magnetic force. The quantity introduced, in mathematical theories of induced magnetisation, depending on the magnetic properties of the substance, is in these treated as a constant; but it was shown, in twelve cases of iron and two of nickel, to vary between wide limits. The author finds that the magnetisation of good iron can never exceed 175,000 times the unit magnetic field (on the metre, gramme, second, system), nor can nickel exceed 63,000 times; and from these data, and with aid of a formula of Prof. Maxwell's for tension of lines of force, it is inferred that the greatest weight which can be sustained by an electro-magnet with an infinite current, is, for iron, 354 Ibs. per square inch of section, and for nickel 46 lbs. The results of experiment closely agreed with this.—Prof. Henry Draper communicates a note on diffraction-spectrum photography, accompanied with a photograph printed by the Albert-type process. (See NATURE, vol. ix. p. 223.)—We note several geological papers, one of them, by Prof. Fontaine, describing a remarkable deposit of bituminous matter, termed Grahamite, in Ritchie County, West Virginia, chemically resembling the mineral Albertite of New Brunswick, but differing considerably from this in its geological relations.—The age of the Lignitic formation of the Rocky Mountain region is far from decided, owing to the contrary evidence afforded by fossil plants and animals; and the editors propose to cite the arguments from various sources, in order, if possible, to bring about agreement. They give in this number the conclusions of M. Lesquereux from fossil plants. He refers the Lignitic beds to the Upper and Lower Eocene; and he gives a number of facts showing the disconnection of American Eocene flora from that of the Cretaceous, indicating truly separate formations.—Mr. Comstock describes the geology of Western Wyoming.—Mr. Verrill communicates the results of a recent dredging expedition on the coast of New England. It was ascertained that the body of cold bottom water approaches so nearly to the Coast of Maine as to manifest itself distinctly within twelve or fifteen miles of Cape Elizabeth, both by its highly Arctic fauna, and its icy temperature, even in summer.—In a letter from Cordoba, dated Sept. 8, 1873, Dr. Gould describes a remarkable swarm of locusts then occurring.