INTRODUCTORY NOTE 



WILLIAM THOMSON, Baron Kelvin of Largs, was born in 

 Belfast, Ireland, June 24, 1824. He was the son of the pro- 

 fessor of mathematics at Glasgow University, and himself en- 

 tered that institution at the age of eleven. By the time he was 

 twenty-one he graduated from Cambridge as Second Wrangler, 

 and, after studying in Paris, he returned to Scotland to become, 

 as professor of natural philosophy, the colleague of his father 

 and elder brother. The story of his life thenceforth is the 

 record of amazingly brilliant and fruitful scientific work, 

 recognised by the award of almost all the honors appropriate 

 to such service, from learned societies, universities, and govern- 

 ments at home and abroad. His part in laying the Atlantic 

 Cable was the occasion of his receiving knighthood, and in 1892 

 he was raised to the peerage. He held his professorship at 

 Glasgow for fifty-three years, and later was chosen its Chan- 

 cellor. He died on December 17, 1907, and was buried in 

 Westminster Abbey. 



Lord Kelvin's activities were remarkable for both profundity 

 and range. A large number of his results are to be appreciated 

 only by the highly skilled mathematician and physicist; but his 

 speculations on the ultimate constitution of matter; his state- 

 ment of the principle of the dissipation of energy, with its 

 bearing upon the age of life on the earth; his calculations as 

 to the age of the earth itself, and much more, are of great 

 general interest. His fertility in practical invention was no less 

 notable. He contrived a large number of instruments, his ser- 

 vices to navigation and ocean telegraphy being especially valu- 

 able. Long before his death he was recognised as the most 

 distinguished man of science of his time and country, and he 

 was also the most loved. 



The lectures which follow are favorable examples of his 

 power of exposition in subjects in which he had no superior. 



