Abstract
LONDON. Royal Society, February 24.—Sir J. J, Thomson, president, in the chair.—Prof. Karl Pearson.: Mathematical contributions to the theory of evolution. XIX.—Second supplement to a memoir on skew variation. This memoir adds certain additional types of frequency curves to those published by the author in memoirs in the Phil. Trans. of 1895 and 1901. It sums up by aid of a diagram the old results and the present additions. It further illustrates by an important general case that frequency curves are distributed oover a wide area of the β1 β2, plane, where β1, β2 are fundamental statistical constants, and that only evil can arise from inflating the Gaussian point (β1 = 0, β2 = 3) to cover the whole of this area. The entire subject is, in the author's opinion, of much importance, as significant differences are in many branches of science determined by the so-called “probable oerror,” of the measured quantities, whether they be means, standard deviations, or correlations. But such “probable errors” have little, if any, meaning, if it can be shown that the sample value is not even the most probable value of the statistical constant in the sampled population, and that the samples are not distributed in a form in the least approaching the Gaussian distribution about the mean value of samples. In every case it is needful to determine the actual frequency distribution, and in nine cases out of ten in samples such as are in common use in psychology, astronomy, or physics-what the statistician terms small samples—it is easy to demonstrate that the distribution is very far from the Gaussian type, but may be markedly skew to such an extent that the ordinary “probable error” is meaningless.—F. P. Burt and E. C. Edgar: The relative combining volumes of hydrogen and oxygen. The gases were measured successively in a constant-pressure pipette at 0° C. and 760 mm. pressure, (1) In the first series hydrogen and oxygen were prepared by electrolysis of barium hydroxide solution. The hydrogen was purified by passage over charcoal cooled in liquid air; the oxygen by liquefaction and fractionation. Mean value for ratio of combining volumes from twelve experiments was 2-00294. The figure 2-00288 is adopted as final value for ratio of combining volumes at 0° C. and 760 mm., pressure. This differs from the value of Scott (2-00285) by only 3 parts in 200,000. The resulting atomic weight for hydrogen (O=16) computed from Morley's value for the density ratio (0·089873/1·42000) is 1·00772, very nearly, the arithmetic mean of Morley's and Noges's values (1·00762 and 1·00787).—W. Mason: Speed effect and recovery in slow-speed alternating stress tests. Repeated cycles of equal direct and reverse torque have been applied to mild steel specimens of tubular form, and systematic measurements made of the range of the corresponding torsional strains. The author attempts to account for variations of strain on the hypothesis of alternate production and hardening of “mobile material” in the steel.—W. M. Thornton: The ignition of gases by impulsive electrical discharge. The ignition of gases by impulsive discharge is considered first as a function of sparking distance. It is shown that the shorter the distance the greater the spark, so that the volumes of the least igniting sparks are, in a typical case, the same for all spark lengths. Ignition may occur with intense momentary brush discharge, generally with the true disruptive spark. The products of combustion are found to be ionised and to carry a positive charge. The gases examined were mixtures in air of hydrogen, methane, propane, and pentane; of ethylene and acetylene; carbon monoxide and cyanogen; coal gas and a mixture of equal volumes of hydrogen and methane. Hydrogen, propane, pentane, and carbon monoxide rise gradually in difficulty as the percentage of oxygen is reduced; methane is ignited by the same spark whatever the percentage of gas may be; acetylene and cyanogen have the stepped atomic type of ignition; ethylene is more inflammable in rich mixture. Hydrogen and methane in equal volumes are ignited as methane in type, hydrogen in magnitude.
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Societies and Academies . Nature 97, 50–52 (1916). https://doi.org/10.1038/097050a0
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DOI: https://doi.org/10.1038/097050a0