Abstract
LONDON. Royal Society, November 4.—Sir Archibald Geikie, K.C.B., president, in the chair.—Colonel Sir David Bruce, Captains A. E. Hamerton and H. R. Bateman, and Captain F. P. Mackie: (1) The development of Trypanosoma gambiense in Glossina palpalis; (2) a note on the occurrence of a trypanosome in the African elephant.—The Lord Rayleieh: The perception of the direction of sound.—Prof. H. M. Macdonald: The diffraction of electric waves.—R. Houstoun: The mechanism of the absorption pectra of solutions.—Hon. R. J. Strutt: (1) Note on the spontaneous luminosity of a uranium mineral; (2) the accumulation of helium in geological time, ii. The second paper is a continuation of that published in Proc. Roy. Soc., A, vol. lxxxi., 1908, p. 272, the object being to determine the ratio of helium to radio-active matter in minerals as a means of measuring their age. The data given refer chiefly to the iron ores of sedimentary strata. Even some of the most recent are found to contain quantities of helium, denoting great antiquity. Thus ironstone from the Eocene beds of Co. Antrim contains, per gram, 2.64 × 10-4 grs. uranium oxide (U3O8), 8.27 × 10-4 grs. thorium oxide, and 12.1 × 10-4 c.c. helium. This, interpreted according to the best available data, would imply an age of thirty million years. Experiments of a preliminary character have been made to determine directly the rate of growth of helium in thorianite and in pitchblende. The data thus obtained will give the rate of formation of helium by the complete series of uranium and thorium respectively, and thus make it possible to interpret more definitely the results of experiments on other minerals for which a direct determination is not feasible; 400 grams of thorianite was found to yield in seven weeks a quantity of helium certainly less than 2 × 10-8 c.c. The annual rate of production per gram of thorianite is, therefore, certainly less than 3.7 × 10-8 c.c. The 9 c.c. initially present cannot, therefore, have accumulated in a less time thnn 240 million years. An experiment on pitchblende of a similar character was consistent with Rutherford's estimate of the rate of production by the uranium series, but was not on a sufficient scale to afford complete confirmation. Experiments on a larger scale are in progress.—J. C. Chapman and H. L. Porter: The physical properties of gold leaf at high temperatures.—Dr. H. C. Pocklingrton: The dimensions and function of the Martian canals. The nature of the bed of the canals is guessed from Lowell's value of the velocity of flow along them, and then the depth is calculated from the technical formulæ, assuming that the canals are horizontal and carry water from pole to pole. The depth is 500 feet if the canals are as narrow as possible, or 370 feet if they are 4500 feet wide. The amount of water required to fill the canals is determined. To find the function of the canals, it is assumed that their arrangement is the most economical, and it is deduced thnf they are essentially lines of communication, though, of course, thev may also serve to carry water for irrigation.
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Societies and Academies . Nature 82, 58–60 (1909). https://doi.org/10.1038/082058a0
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DOI: https://doi.org/10.1038/082058a0