During his residence at Cambridge Thomson gained the friendship of George Gabriel Stokes, who had graduated as Senior Wrangler and First Smith's Prizeman in 1841. They discussed mathematical questions together and contributed articles on various topics to the _Cambridge Mathematical Journal_. In 1846 "Cambridge and Dublin" was substituted for "Cambridge" in the title of the Journal, and a new series was begun under the editorship of Thomson. A feature of the earlier volumes of the new issue was a series of Notes on Hydrodynamics written by agreement between Thomson and Stokes, and printed in vols. ii, iii, and v. The first, second, and fifth of the series were written by Thomson, the others by Stokes. The matter of these Notes was not altogether novel; but many points were put in a new and more truly physical light, and the series was no doubt of much service to students, for whose use the articles were intended. Some account of these Notes will be given in a later chapter on Thomson's hydrodynamical papers. For the mathematical power and sure physical instinct of Stokes Thomson had always the greatest admiration. When asked on one occasion who was the most outstanding worker in physical science on the continent, he replied, "I do not know, but whoever he is, I am certain that Stokes is a match for him." In a report of an address which he delivered in June 1897, at the celebration of the Jubilee of Sir George Stokes as Lucasian Professor of Mathematics, Lord Kelvin referred to their early intercourse at Cambridge in terms which were reported as follows: "When he reflected on his own early progress, he was led to recall the great kindness shown to himself, and the great value which his intercourse with Sir George Stokes had been to him through life. Whenever a mathematical difficulty occurred he used to say to himself, 'Ask Stokes what he thinks of it.' He got an answer if answer was possible; he was told, at all events, if it was unanswerable. He felt that in his undergraduate days, and he felt it more now." After the death of Stokes in February 1902, Lord Kelvin again referred, in an enthusiastic tribute in Nature for February 12, to these early discussions. "Stokes's scientific work and scientific thought is but partially represented by his published writings. He gave generously and freely of his treasures to all who were fortunate enough to have an opportunity of receiving from him. His teaching me the principles of solar and stellar chemistry when we were walking about among the colleges sometime prior to 1852 (when I vacated my Peterhouse Fellowship to be no more in Cambridge for many years) is but one example."