Page:Lectures on Ten British Physicists of the Nineteenth Century.djvu/25

 and founded in connection a chair of experimental physics. Sir William Thomson was invited to become a candidate, but declined; Maxwell was invited, and after some hesitation acceded. He was elected without opposition. For some time after his appointment Maxwell's principal work was that of designing and superintending the erection of the Cavendish Laboratory, so-called after the family name of the donor. It was opened in 1874. In the following vacation I visited it, but Maxwell as was his wont, had gone to his country home. His assistant mentioned that the equipment was far from complete, and that they were afraid that the Duke of Devonshire might die before his promise of a complete equipment had been availed of. It was not till 1877 that the equipment was completed.

Soon after (1873) he became Cavendish professor he delivered the famous "Discourse on Molecules" in an evening lecture before the British Association, then assembled in Bradford. Maxwell viewed the doctrine of evolution, or at any rate the extreme consequences deducible from that doctrine, with marked disfavor. This dislike originated in part from his bias as a Christian and a theist, but it rested also on philosophical convictions which he set forth in this address. The conclusion is as follows: "In the heavens we discover by their light, and by their light alone, stars so distant from each other that no material thing can ever have passed from one to another; and yet this light, which is to us the sole evidence of the existence of these distant worlds, tells us also that each of them is built up of molecules of the same kinds as those which we find on earth. A molecule of hydrogen, for example, whether in Sirius or in Arcturus, executes its vibrations in precisely the same time. Each molecule therefore throughout the universe bears impressed upon it the stamp of a metric system as distinctly as does the meter of the Archives at Paris, or the double royal cubit of the temple of Karnac. No theory of evolution can be formed to account for the similarity of molecules, for evolution necessarily implies continuous change, and the molecule is incapable of growth or decay, of generation or destruction.