Ramsay's opinion was that Kelvin "was not what would be called a good lecturer; he was too discursive." Ramsay doubted whether any man "with a brain so much above the ordinary, so much more rapid in action than the average, can be a first-rate teacher.... But Kelvin never allowed the interest of his students to flag. His aptness in illustration and his vigour of language prevented that. Lecturing one day on 'Couples', he explained how forces must be applied to constitute a Couple and illustrated the direction of the forces by turning around the gas-bracket. This led to a discussion on the miserable quality of Glasgow coal-gas and how it might be improved. Following again the main idea, he caught hold of the door and swung it to and fro; but again his mind diverged to the difference in the structure of English and Scottish doors. We never forgot what a 'Couple' was—but the idea might have been conveyed more succinctly." Yes, and ten to one the receivers of it would have forgotten what a "Couple" was!
I heard Kelvin address the Royal Society in London while he was president of that body. He had invited me to come, and I was curious enough to see the most distinguished scientific body in the world learning something from the world's most distinguished mathematician, electrician, and natural philosopher. The hall in Burlington House was filled. Had an earthquake swallowed the hall then, the world would have been deprived instantaneously of dozens of men who were doing its thinking for it. The subject of the discourse was not thrilling, nor could the lecturer have been accused of an attempt to pander to popularity. The subject was "The Homogeneous Division of Space." There shot through the hour's talk a stream of descriptive phrases such as "tetrakaidekahedronal cells", "parallelepipedal partitionings", "enantiomorphs ", and their progeny.
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, 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 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.
The first pair of telephonic instruments that Alexander Graham Bell brought to Europe were presented by him to Lord Kelvin, who immediately put them to use by connecting his house with that of his brother-in-law and assistant, Doctor J. T. Bottomley. The first electrically lighted house in the world was the first in the old world to be connected by telephone for purposes professional, social, personal, and domestic. For how could Kelvin, who was always peering into the future, be afraid of new things? He peered into the past, too, for you remember how he startled the orthodox mind by his calculations regarding the age of the earth.
Lord Salisbury, just before he became Prime Minister for the last time (his long term of 1895-1902) was Chancellor of the University of Oxford and at the same time President of the British Association for the Advancement of Science. At Oxford, in a memorable year, and in behalf of the University of which he was chancellor, he welcomed the association of which he was president, and he reminded his learned listeners that Lord Kelvin, whom he alluded to as "the greatest living master of natural science amongst us", was the first to point out that the amount of time required by the advocates of the Darwinian theory for the working out of the process of evolution which they had imagined "could not be conceded without assuming the existence of a totally different set of natural laws from those with which we are acquainted." Hot things cool. The once seething earth has cooled and is cooling. So many million years ago it must have been hotter than now by calculable degrees. "But if at any time it was hotter at the surface by fifty degrees Fahrenheit than it is now, life would then have been impossible on this planet."
Lord Kelvin assured us that organic life on earth cannot have existed more than a hundred million years ago. So if you believed in Archbishop Ussher's chronology, and niggardly dealt out to the earth an age of only six thousand years, or went so far as Professor Tait with his ten million, you had, by Kelvin's figuring, a tremendous margin to fill up somehow. Of course the orthodox jumped and squealed. But the geologists and biologists stamped and yelled. Some of them wanted more than Kelvin's stingy allowance; they wanted not one hundred million years, but hundreds of millions. And there was a pretty ferment in the camps!
Sir William Ramsay I have quoted on Kelvin's illustration, in the class room, of the term "acceleration." Kelvin maintained speed when he had got it up. Remember that he was lame, and consider his energy. He would dart at an object that stood a few feet from him, on his lecture-bench, use it for whatever demonstration was required, and then dart at another, or at the blackboard, or at the pointer, as if he were a busy bee extracting honey from the flowers. There was certainty about everything he did; no hesitation, no floundering, no hemming and hawing for a word, or the next act. His lameness merely lent emphasis to the fact that he was walking; it did not prevent his swiftness of movement. Across the grounds of the university I toiled after him like "panting time." He gave the impression of readiness for a race, and might challenge you at any minute. His gown was always streaming behind him, his mortar-board cap in imminent danger of blowing off in the breeze stirred by his advance. Well, he had raced the world many years and had always won.
Some great men are so impressed by their own greatness that their manner becomes ponderous and vast as if they lived in a belief that they cast shadows on the sun. Not so Lord Kelvin, who never seemed to think that great men thought him a greater than themselves. His manner was simple, gentle, courteous, and direct. He was easy to talk with, and yet he had no small talk. But it was not easy to answer his questions. There was never such a man as he for asking questions unless it were the Chinese Viceroy, Li Hung Chang. Whatever your profession, trade, interests in life, he would put questions that went to the roots of your matter and revealed on his part a greater knowledge of the problems involved than you dreamed existed. By tireless questioning he learned. But where Li Hung Chang turned the results of his questioning to his own benefit, Kelvin applied them to the good of the world. Yet when, in 1896, they celebrated the fiftieth anniversary of his professorship at Glasgow he was, I take it, the most surprised man in all the galaxy of the famous. The dear old gentleman with the domed head, the white hair, and generous white beard seemed to be asking himself, "What next? Why all this fuss and feathers?" But he was apparently genuinely pleased, too, for all the tributes bespoke honest admiration of achievement and character. Fifty-one learned societies, twelve colleges, and twenty-eight universities were represented. They were of all countries. That day the world, and all that was therein, lifted its hat to Lord Kelvin.