The Times Great Scottish Lives: Obituaries of Scotland’s Finest. Magnus Linklater

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      A direct and immediate result of Lord Kelvin’s study of Carnot’s work was his definition of the ‘Absolute scale of temperature’ – that is, a scale which, unlike the graduations of an ordinary thermometer that are based on the observed alterations in volume produced in a particular material by heat or cold, is independent of the physical properties of any specific substance. A second addition to science soon followed in the principle of the dissipation of energy, enunciated in 1852. A further general inference is that this earth, as now constituted, has been within a finite time, and within a finite time will again become unfit for human habitation.

      In a paper communicated to the Royal Society of Edinburgh in 1862 he declared that for 18 years it had been pressed on his mind that much current geological speculation was at variance with essential principles of thermodynamics, and proceeded to show from considerations founded on the conduction of heat that the earth must within a limited time have been too hot for the existence of life. Six years later, in an address on ‘Geological Time’ which provoked a lively controversy with Huxley, he brought some other physical considerations to bear on the question.

      Since the tides exercise a retarding influence on the rotation of the earth, it must in the past have been revolving more quickly than it does now, and calculations of its deceleration indicate that within the periods of time required by some geologists it must have been going at such a speed that it could not have solidified into its present shape. But Lord Kelvin did not think the amount of centrifugal force existing 100 million years ago incompatible with its present form. Again he pointed out that the sun cannot be regarded as a permanent and eternal factor in the universe.

      It is only fair, however, to say that his arguments have not been universally endorsed even among physicists; and it has been urged that there are other assumptions – in regard, for instance, to the conductivity of the earth’s interior – not less admissible than those adopted by him, which lead to results much more favourable to the geological and biological demand for more time. Radium, too, has been invoked to explain the maintenance of the sun’s heat.

      Great as were Lord Kelvin’s achievements in the domains of scientific speculation, his services to applied science were even greater. A prolific and successful inventor, he had nothing in common with that frequent class of patentees who are brimming over with ideas, all crude, most worthless, and only in occasional instances capable of being worked up into something valuable by men combining the requisite mechanical skill with an adequate knowledge of scientific first principles. Invention with him was not a mere blind groping in the dark, but a reasoned process leading to a definitely conceived end.

      Of the scores of patents he took out few have not been found of practical and commercial value. It was in connection with submarine telegraphy that some of his most valuable inventions were produced in this department, indeed, his work was of capital importance and of itself sufficient to establish his title to lasting fame. Lord Kelvin was a firm believer in the practicability of transoceanic telegraphy and did not hesitate to show by acts the faith that was in him. He became a director of the Atlantic Telegraph Company, which hazarded large sums in the enterprise of making and laying a cable, and he took an active and personal part in the operations which culminated in the successful laying of the short-lived cable of 1853.

      As is well known, the system broke down completely after it had been in use for a very short time, and there is little reason to doubt that the reason of its untimely end was the inability of its insulation to stand the potentials to which it was exposed. Lord Kelvin, who believed that but for this treatment the cable would have worked satisfactorily, declared that feeble currents ought to be employed together with very sensitive receiving instruments, and, characteristically, was ready, not only with a theoretical prescription, but with the working instrument, his mirror galvanometer, that enabled it to be carried into effect.

      Some of his finest work is to be found in his electric measuring instruments, a subject in which his knowledge and authority were unrivalled. More especially was this the case in regard to electrostatic measurements – perhaps the most difficult of all. When the need for accurate instruments in his studies on atmospheric electricity caused him to take up the matter, the electrometers in existence were little more than electroscopes – capable of indicating a difference of electric potential, but not of measuring it; but in his quadrant, portable, and absolute electrometers his skill and ingenuity put at the disposal of electricians three beautiful instruments of exact research.

      Measurement he regarded as the beginning of science and as the origin of many of the grandest discoveries. Hence he was always ready to do anything by which it could be facilitated, whether in matters of daily life or abstruse scientific inquiry. Thus on the one hand the metric system found in him a strong supporter, and he rarely missed a chance of bestowing a word or two of half-humorous disparagement upon the unhappy English inch or ‘that most meaningless of modern measures, the British statute mile.’

      A keen amateur yachtsman, he developed navigational aids for ships, a steady compass that could still work accurately when a ship rolls at sea, and a sounding mechanism to measure depth at regular intervals.

      As a lecturer Lord Kelvin was rather prone to let his subject run away with him. When this happened, limits of time became of small account, and his audience, understanding but little of what he was saying, were fain to content themselves with admiring the restless vivacity of his manner (which was rather emphasised than otherwise by the slight lameness from which he suffered) and the keen zest with which he revelled in the intricacies of the matter in hand. Similarly, the intelligence and patience of his Glasgow classes were not always equal to the mental strain entailed by his expositions, and, though they were thoroughly proud of him and his attainments, their orderliness was not of the strictest kind, and they were not above varying the proceedings with an occasional practical joke. But he was quick to express his approval of a piece of good work, or his delight at a new result or well-planned experiment; and no one could come in contact with him without feeling the charm of his kindly, lovable nature, and falling under the spell of the enthusiasm and untiring energy with which he devoted himself to the advancement of knowledge.

      Lord Kelvin was twice married; first, to Margaret, daughter of Mr. Walter Crum, of Thornliebank; and, secondly to Frances Anna, daughter of Mr. Charles R. Blundy, of Madeira. There was no issue of either marriage.

      A devout Christian, Kelvin believed that his theory of heat-death and his calculations of the age of the earth exposed flaws in Charles Darwin’s idea of evolution. To some Victorians, however, the implications of his ideas about the finite habitability of the earth seemed to offer a doom-laden vision of an icy end to all things rather than a fiery one.