The oscillatory character of the discharge of the Leyden jar, the foundation of the work of H. R. Hertz and of wireless tele graphy, were investigated by him in 1853.
It was in 1873 that he undertook to write a series of articles for Good Words on the mariner's compass. He wrote the first, but so many questions arose in his mind that it was five years before the second appeared. In the meanwhile the compass went through a process of complete reconstruction in his hands, a process which enabled both the permanent and the temporary magnetism of the ship to be readily compensated, while the weight of the Io-in. card was reduced to one-seventeenth of that of the standard card previously in use, although the time of swing was increased. Thomson also invented his sounding appa ratus, whereby soundings can be taken in shallows and in deep water. Thomson's tide gauge, tidal harmonic analyser and tide predicter are famous, and among his work in the interest of navigation must be mentioned his tables for the simplification of Sumner's method for determining the position of a ship at sea. Thomson published more than 300 original papers bearing upon nearly every branch of physical science. It is only by reference to his published papers that any approximate conception can be formed of his life's work; but the student who had read all these knew comparatively little of Lord Kelvin if he had not talked with him face to face. Extreme modesty, almost amounting to diffidence, was combined with the utmost kindliness in Lord Kelvin's bearing to the most elementary student, and nothing seemed to give him so much pleasure as an opportunity to acknowledge the efforts of the humblest scientific worker. The progress of physical discovery during the last half of the 19th century was perhaps as much due to the kindly encouragement which he gave to his students and to others who came in contact with him as to his own researches and inventions; and it would be difficult to speak of his influence as a teacher in stronger terms than this.
In 1866, perhaps chiefly in acknowledgment of his services to trans-Atlantic telegraphy, Thomson received the honour of knighthood, and in 1892 he was raised to the peerage with the title of Baron Kelvin of Largs. The Grand Cross of the Royal Victorian Order was conferred on him in 1896, the year of the jubilee of his professoriate. In 1890 he became president of the Royal Society, and he received the Order of Merit on its insti tution in 1902. In 1896, on the occasion of the jubilee of his professorship, the city authorities joined with the university in honouring their most distinguished citizen. Three years after this celebration Lord Kelvin resigned his chair at Glasgow, though by formally matriculating as a student he maintained his connection with the university, of which in 1904 he was elected chancellor. Much of his time after his retirement was given to writing and revising the lectures on the wave theory of light which he had delivered at Johns Hopkins university, Baltimore, in 1884 (published 1904). At the Leicester meeting of the British Association in 1884 he delivered a long and searching address on the electronic theory of matter. He died on Dec. 17, 1907, at his residence, Netherhall, near Largs, Scotland; there was no heir to his title, which became extinct. A statue was erected to him at Glasgow in 1913.
In addition to the Baltimore lectures, he published with Professor P. G. Tait a standard but unfinished Treatise on Natural Philosophy (1867) . A number of his scientific papers were collected in his Reprint of Papers on Electricity and Magnetism (1872) , and in his Mathematical and Physical Papers (1882, 1883 and 189o) , and three volumes of his Popular Lectures and Addresses appeared in See Andrew Gray, Lord Kelvin (1908) ; S. P. Thompson, Life of Lord Kelvin ( 910) , which contains a full biblography of his writings.