American Journal of Science, November.—This number opens with an interesting address by Mr. R. S. Woodward at the last meeting of the American Association, on the mathematical theories of the earth, in which emphasis is laid on the incompleteness of those hitherto advanced.—From a simple investigation, Mr. R. Hooke concludes that for planetary bodies assumed to have the same surface density (i.e. those in which solidification has taken place), the increase of the difference between the mean and surface density is proportional to the increase of the diameter. He tests this by computation of the mean densities of the inner planets from their assigned diameters, and further confirmation is derived from the case of Jupiter's satellites, He also applies the law to computing the ultimate diameters and mean densities (i.e. after solidification) of the sun and outer planets.—Regarding Tschermak's theory of the mica group as inadequate, Mr. F. W. Clarke offers the view that all the micas, vermiculites, chlorites, margarite, and the clintonite group, may be simply represented as isomorphous mixtures, every constituent being a substitution derivative of normal aluminium poly- or ortho-silicate.—Mr. E. O. Hovey studies the low trap ridges (some six lines of them) of the East Haven-Branford region in Connecticut; he considers all the trap intrusive, and the western dikes, at least, of later origin than the tilting of the sandstone.—Mr. C. Lea contends that subchloride, and not oxychloride, is the product of the action of light on silver chloride.—There are also papers on an improved standard Clark cell with low temperature coefficient, by Mr. H. S. Carhart; on pseudomorphs of native copper after azurite, from Grant County, New Mexico, by Mr. W. S. Yeates; and on the relation of volume, pressure, and temperature, in case of liquids, by Mr. C. Barus.