He had a "keen mathematical instinct," as Prof. Silvanus P. Thomson puts it in a letter to the writer, an insight that "grew to see things." He often left matters in the dark for years, then returned to see them in the clear light of truth. At the age of sixteen, he wrote a mathematical essay on the figure of the earth; and at eighty-three, took it up again in order to add a note to the argument! Thomson was discursive in his lectures, and was never able to boil the matter down to suit the taste and digestive powers of the ordinary student. The activity of his mind and its fecundity were such that new ideas, new problems, new modes of treatment were continually occurring, and with such fascination that he would leave the main subject to indulge in what often proved prolonged digressions. One of his bugbears was our system of weights and measures, which he denounced in season and out of season as "insane," "brain-wasting" and "dangerous." Occasionally epithets of a more caloric nature would escape the lips of the indignant Professor, who, as a consequence of his denunciation, had always to be indulgent to students who chanced to be shaky in the matter of Troy weight, avoirdupois weight or even apothecaries weight. In later years, I heard Lord Kelvin at the Royal Institution, London, on some of his favorite dynamical subjects, such as the gyrostat, vortex rings and the like. However impressed by his keen eye, intellectual forehead, his mastery of the subject and wealth of illustration, I was no less impressed by his vivacity, his enthusiasm and the rapidity with which he could leave a train of thought and return to it again. At meetings of the British Association, he always had something illuminating to say; but not infrequently, carried away by a torrent of ideas, he would indulge in a superfluity of detail, forgetting that other speakers had to be heard and other papers read. The idea of connecting the Old World with the New by means of an electric cable laid on the bed of the ocean, seemed to most people in the 'fifties quixotic and utopian. Manufacturers said such a cable could not be made; engineers, that it could not be laid; electricians, that it could not be worked; and financiers, that if laid and worked, it would never pay. But with a Field to look after the financial interests of the scheme, and a Thomson to attend to electrical quantities, there was no tilting at windmills, and the utopian scheme became in due time the cable whose core pulsated with the news of the world.