Scientific Serials

Abstract

American Journal of Science, February.—The magnetic field in the Jefferson Physical Laboratory, by R. W. Willson. One of the wings of this Laboratory in Harvard University has been constructed wholly without iron for the purpose of research, and the author has made a series of experiments to determine how far the end sought has been gained. He has found the magnitude of the disturbance which may arise in practice from such objects as stoves and iron pipes, and has made the interesting discovery that the brick piers of the building have a sufficient amount of free magnetism to produce quite an appreciable effect. —On Cretaceous plants from Martha's Vineyard, by David White. The author has studied a number of fossil plants collected at several localities and horizons in the Vineyard series for the purpose of solving the question as to the age of the underlying clays, lignites, and sands, of Martha's Vineyard. He concludes that the evidence from the fossil plants bespeaks an age decidedly Cretaceous, and probably Middle Cretaceous, for the terrane in which they were deposited.—Review of Dr. R. W. Ell's second report on the geology of a portion of the Province of Quebec, with additional notes on the “Quebec group,” by Charles D. Walcott. The geological systems recognized in the area reported upon include the Devonian, Silurian, Cambro-Silurian (Ordovician), Cambrian, and pre-Cambrian.—Measurement by light-waves, by Albert A. Michelson. The telescope and microscope are compared with the refractometer, some remarkable analogies in their fundamental properties are pointed out, and a few cases in which the last-named instrument appears to possess a very important advantage over the others illustrated. Previous experiments have shown that the utmost attainable limit of accuracy of a setting of the cross-hair of a microscope on a fine ruled line was about two-millionths of an inch, whereas direct measurements of the length of a wave of green light emitted by incandescent mercury vapour, show that the average error in a setting was only about one ten-millionth of an inch. The method is also extended to angular and spectrometer measurements.—On lansfordite, nesquehonite, a new mineral, and pseudomorphs of nesquehonite after lansfordite, by F. A. Genth and S. L. Penfield. The authors have examined the crystallization of lansfordite (3MgCO3˙Mg(OH)221 H2O), and another new mineral having the composition MgCO3˙3H2O, which has been named nesquehonite. A crystallized artificial salt of the same composition is also described.—Weber's law of thermal radiation, by William Ferrel. An examination of Weber's new law, and a test of his formula by means of experimental results, in which the absolute rate of losing heat is determined from the observed rate of cooling of heated bodies of known thermal capacity, and the relative rate from the galvanometer needle of the thermopile.—Tracks of organic origin in rocks of the Animikie Group, by A. R. C. Selwyn. Traces of fossils, or what are supposed to be such, have been discovered in the Animikie rocks of Lake Superior. The fact is interesting and important, for, if the black Animikie shales represent the Lower Cambrian of the Atlantic border, the Paradoxides and Olenellus fauna will probably be found in them sooner or later.