The genial old gentleman on the platform would rest his weight upon his hands on the table, or the lecture-desk, and lean forward towards his audience, and tell some puzzling facts about nature's puzzles, {105} pouring streams of numbers and their multiplications and divisions into their ears while they floundered in the mathematical deluge. He would see that he had them puzzled, that his mind was working too fast for them; he must have surmised it from the expressions on their faces, for while he announced theories, discoveries, and drew conclusions, they, with all their knowledge and experience, would look as blank or bewildered as schoolboys, and he would step back from the table and, with a winning smile, remark, "It's this way", or "After all, it's simpler than it seems", or "I think it would be demonstrated so", and turning swiftly on one heel would face the blackboard and draw upon it in strokes that were like flashes, a diagram which made it all so clear that his hearers chuckled, or laughed outright; then swiftly he would turn again and face them with that winning smile which seemed to mean, "See how simple it is!" Then they would applaud him, which is very difficult for the Royal Society to do. Lord Kelvin's was the first house in the world to be lighted by electricity throughout. He utilized the current in every nook and corner, in attics and cellars, in cupboards, closets and wardrobes, long before anybody else had attempted to do so. This was when everybody else thought electric lighting a luxury, but his purpose was to prove it a necessity. That was his way. Whenever he acquired new knowledge he applied it forthwith to the betterment of the human lot. He thought that science for the sake of science, or scientists, was as stupid a formula as "art for art's sake." Cheese for cheese's sake {106} would be quite as useful to mankind. Of what use was knowledge if it were not applied to the needs of man? He was a yachtsman, but not for sporting purposes, or faddishness, or luxurious idleness. He loved the sea, and his yacht, a schooner named _Lalla Rookh_, enabled him to wrest from the sea some of its secrets. For twenty years he went sailing every summer, living aboard weeks at a time. He held the certificate of a master navigator. It was on board the _Lalla Rookh_ that he invented his famous apparatus for taking soundings and his no less famous compass. These things became necessities for navigators.