Abstract
LONDON. Royal Society, May 7.—Sir William Crookes, president, in the chair.—Lord Rayleigh; (1) Some calculations in illustration of Fourier's theorem. (2) The theory of long waves and bores.—Sir Joseph Larmor and J. S. B. Larmor: Protection from lightning and the range of protection afforded by lightning rods. On modern ionic views discharge in the atmosphere should originate at a place of maximum intensity of electric field and spread both ways from it along a line which should be roughly the line of force. The explanation of branching, zigzag, and multiple lightning discharges is to be sought on these lines. The introduction of a narrow linear conductor cannot sensibly disturb a steady field of force, and not at all if it is transverse to the field. Thus it would seem to be the top of the building itself, not of the lightning conductor, that attracts the discharge, and the function of a single rod can only be to lead it more safely away. But a number of rods distributed over the area of the roof, and effectively connected to earth by a conductor, can, by their joint action, lift the intensest part of the field from the top of the building to the region around their summits, and so obviate or much mitigate the danger of discharge from above to the building which they cover. In illustration, diagrams are given^of a vertical field of force as disturbed by vertical pillars of semi-ellipsoidal form and of various breadths, or by an earthed conducting region overhead, such as might be originated by gradual discharge from a pointed rod.—Prof. A. Schuster: Newcomb's method of investigating periodicities and its application to Bruckner's weather cycle.—E. N. Da C. Andrade: The flow in metals subjected to large constant stresses. The law connecting the extension with time for wires of various metals subjected to large stresses has been examined at different temperatures. The stress was kept constant throughout the flow by the device of a hyperbolic weight employed in former experiments. The different types of flow observed for different metals at room temperature are only particular cases of one general law governing the flow of all single metals, and can all be found for one metal by choosing an appropriate temperature; thus, soft iron at 450° C. behaves similarly to lead at 15° C.—G. I. Taylor: Eddy motion in the atmosphere. The paper contains a theoretical discussion of the function of eddies in conveying heat and momentum through a fluid. It is shown also that measurements of the temperature of the air over the Great Bank of Newfoundland made by the author last year, lead to the conclusion that eddies extend upwards over the sea to a height of at least 800 metres; and that there is no appreciable diminution in their size or intensity at this height. On the assumption of a uniform amount of eddy motion, the velocity of the wind at various heights above the ground is calculated, and shown to agree with the most recent observations carried out over Salisbury Plain.—Prof. Ernest Wilson: The properties of magnetically-shielded iron as affected by temperature. In a paper recently read before the Royal Society, it is shown that if stalloy in ring form is shielded from the earth's magnetism and subjected to a considerable magnetising force at atmospheric temperature, the permeability can be increased. The present experiments deal with the effect of allowing stalloy to cool down through the temperature at which it regains magnetic quality when in a shield and when under the influence of a magnetising force due to a continuous current. Two specimens have been subjected to this treatment, and in each case the maximum permeability has a value of above 10,000 when the specimen is at atmospheric temperature.
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Societies and Academies . Nature 93, 287–289 (1914). https://doi.org/10.1038/093287a0
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DOI: https://doi.org/10.1038/093287a0