Page:Popular Science Monthly Volume 75.djvu/519

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two great advances of modern science, perhaps the two most notable human achievements, are the doctrine of organic evolution and the doctrine of the conservation of energy. All the world has this year been celebrating the hundredth anniversary of Darwin's birth. William Thomson, born fifteen years later, occupies in the physical sciences a position almost equal to that of Darwin in the biological sciences. It is a striking fact that Great Britain should have produced these two great men in the same rank with Newton, by whom, and near Darwin, Kelvin nearly two years ago was buried in Westminster Abbey.

Thomson, like Darwin, appears to have been impressed with hereditary genius; his father was professor of mathematics and his brother professor of engineering. Unlike Darwin, typifying a distinction which seems to obtain between the mathematical sciences and the sciences of observation, Thomson was precocious. He matriculated at Glasgow University at the age of ten and attended his father's classes in mathematics. He published a mathematical paper of consequence before going to Cambridge as a student at the age of seventeen, and during his years as an undergraduate at Peterhouse, he published a number of papers on mathematical physics, which fully represented the direction and characteristics of the work which was continued for more than sixty years. He became professor of natural philosophy at the University of Glasgow at the age of twenty-two. At Cambridge Thomson rowed on his college boat and won the Calquhoun sculls, one of the chief athletic competitions of the university. He was one of the founders of the musical society of the university and played at its concerts.

This vigorous versatility was maintained to the end of his long life. The laying of the Atlantic cable, the fixing of units on which electrical engineering is largely based, the invention of electrical and other instruments, many of which were patented and produced a large fortune, seem almost incompatible with his theoretical work in mathematical physics, though it is true that his mathematical analyses were kept in close touch with actual facts. It seems odd to an American that he should have changed the name that had become familiar and famous, if indeed the peerage itself is worth while I when there are no heirs to whom it can be bequeathed. Darwin, to whom no peerage was offered but who bequeathed his name and a large measure of his scientific genius to his sons, seems in this respect to have enjoyed the better fortune. Kelvin visited this country three times and is associated with it both by his work on the Atlantic cable and by the fact that some of his most important theoretical deductions were made known in the form of lectures at the Johns Hopkins University.

An admirable account of Kelvin's scientific work has been contributed to the Proceedings of the Royal Society by Sir Joseph Larmor. From this monograph we reproduce three portraits—the two earlier ones on a reduced scale. It would be fortunate if it were possible to reproduce the lucid exposition of the development of Kelvin's contributions to science and their relations to the work of his predecessors and contemporaries.

In 1848 it was possible for Thomson to maintain the view that heat is a substance which may produce energy