Abstract
American Journal of Science, August.—On the observation of sudden phenomena, by S. P. Langley. The paper deals with the apparently inherent defects of human observation, especially in recording unexpected natural phenomena, its object being to reduce this personal error to a minimum. The author believes that a means may be found by which any person, skilled or ignorant, may make not only meridian observations, but an observation of any sudden visible event, of whatsoever nature, so accurately that no correction need be applied. An instrument constructed for the purpose, and here illustrated, has been tried by various observers in various ways, the probable error for any single observation being rather less than one-twentieth of a second.— A spectro-photometric comparison of sources of artificial illumination, by Edward L Nichols and William S. Franklin. These experiments, made in Cornell University during the summer of 1888, consist in the spectro-photometric comparison of various artificial sources of light and of daylight with that emitted by a sixteen candle-power incandescent lamp. The sources of light subjected to measurement were a standard candle, various petroleum and illuminating gas flames, a lime-light, two electric are lights, clear daylight, an incandescent lamp of high resistance at various temperatures, and an incandescent lamp of low resistance at normal candle power. The general result is that candle-power as determined by means of the Bunsen photometer affords no correct measure either of light-giving energy or of the luminosity of the source of light, the direction of the error always being such as to favour sources of a low degree of incandescence when compared with those of higher temperature.—On the possibility of hemihedrism in the monoclinic crystal system, with especial reference to the hemihedrism of pyroxene, by George H. Williams. A fresh study of the remarkable crystals of pyroxene from Orange County, New York, recently described by the author as hemimorphic, seems to show that they should rather be regarded as hemihedral, and that they are by no means an isolated instance of this peculiar development in pyroxene.—On the earlier Cretaceous rocks of the north-western portion of the Dominion of Canada, by George M. Dawson. The purpose of this paper is to call attention to certain facts recently brought to light respecting the equivalency of the Queen Charlotte Islands and Kootanie formations, and to the importance of the earlier Cretaceous rocks, of which they are representatives, over great areas of the western and extreme north-western portion of the continent. These facts are just now specially interesting from their analogy to those lately developed by Mr. R. T. Hill respecting a similar earlier Cretaceous formation in the southwestern region of the United States.—A new occurrence of gyrolite, by F. W. Clarke. This specimen, from the New Almaden quicksilver mine, California, is shown on analysis, and by comparison with How's figures for a Nova Scotia gyrolite, to be a somewhat impure gyrolite associated with apophyllite, and agreeing approximately with the formula Ca2Si3O8. 3H2O—On action of light on allotropic silver, by M. Carey Lea. The author's further studies of this subject show that light can convert yellow or red-yellow allotropic silver to white, and cause the blue-green modification to pass to the gold-yellow.—Papers were contributed by J. F. Kemp, on certain porphyrite bosses in North-Western New Jersey; by W. B. Dwight, on recent explorations in the Wappinger Valley limestones and other formations of Dutchess County, New York; by George F. Becker, on silicic acids; and by O. C. Marsh, on gigantic horned Dinosauria from the Cretaceous. Mr. Marsh also continues his memoir on the discovery of Cretaceous Mammalia, illustrating the subject with two plates of the teeth of American Cretaceous mammals.
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Scientific Serials. Nature 40, 404 (1889). https://doi.org/10.1038/040404a0
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DOI: https://doi.org/10.1038/040404a0