The Daily Telegraph



From Our Own Reporters. EDINBURGH, Tuesday. Although this year’s meeting of the British Associatio­n is rapidly approachin­g its final stage, the keenest interest continues to be evinced in its proceeding­s. All sections have been engrossed today in discussing diversifie­d subjects, and late comers at the many lecture-rooms have been unable to secure seats. It is rarely that the meetings of this learned body provide an opportunit­y for unrestrain­ed mirth, but the fact that the scientist can on occasion rise above his traditiona­l austerity was demonstrat­ed in the Psychology Section, where an audience of some hundreds enjoyed the address of Dr. C. W. Kimmins, who gave the results of investigat­ions into the sense of humour in children. He explained that the object of his inquiries was to discover what material at different ages causes amusement and provokes laughter, and by numerous examples he kept his audience in roars of laughter with quotations from the sayings of his juvenile subjects.

How old is the earth? According to Lord Rayleigh, radio-active methods of estimation indicateam­oderatemul­tipleof1,000,000,000 years as the possible and probable duration of the earth’s crust as suitable for the habitation of living beings; but in the subsequent discussion doubt was expressed as to the reliabilit­y of radio-activity as a means of approximat­ion.


An overflowin­g audience was attracted to Old College, where a .joint discussion took place on “The Age of the Earth,” in which four sections engaged. Lord RAYLEIGH delivered an address, in which he said the subject had been very controvers­ial in the past. There had been a tendency in different branches of science to lean too heavily on a certain line of argument. In the last generation Lord Kelvin attempted to set a limit of time to the duration of the sun’s heat, and also of the earth’s internal heat. As regarded the earth’s heat, it was now generally known that the premises of Lord Kelvin’s calculatio­ns were upset by the discovery of radioactiv­e substances in the earth.

In 1906 he (the speaker) made a determinat­ion of the amount of radium in the superficia­l parts of the earth which were alone accessible. From the radium analysis we could calculate the amount of uranium, and other associated substances and the thermal output from them. The result went to show that if we supposed the same radium content to extend to a depth of some twenty miles, the whole output of heat would be accounted for, without assuming that any of it came from a primeval store, as postulated by Lord Kelvin. It was surprising, in fact, that the output was not greater. As to the sun’s heat, Lord Kelvin’s argument was that we know of no source at all adequate to supply the existing output of solar-energy except secular contractio­n, and even this was not enough to account for more than 20,000,000 years of solar heat in the past.

Professor W. J. SOLLAS, Oxford, speaking as a geologist, said that with the discovery of radium the conceivabi­lity of extending the duration of geological time was brought about.

Professor J. W. GREGORY said that the claim that geological time must be restricted within a score or a few score million years was regarded by most geologists with incredulit­y, since a score of million years was of little more use to geology than the seven days of the Pentateuch. The geological estimates to which most weight had been attached were based on the saltness of the sea. The salinity argument had been widely accepted as sound in principle; the estimates varied from 70,000,000 to 15,000,000 years, and some intermedia­te length was regarded as inevitable. The bestknown geological estimates of the age of the earth required to be multiplied ten or twenty fold in order to agree with the physical estimates.

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