This testimony is important, if only for comparison with the far different feelings with which his more official pupils regarded him in after years. In these occupations he spent the two years succeeding his degree; for the amount of special work done for the Fellowship Examination was probably not great. He was elected Fellow in October 1817; and in the summer of the following year was made one of the assistant-tutors. With this appointment the first part of his University career ends, and the second begins. His connexion with the educational staff of Trinity College, first as assistant-tutor, then as sole tutor, lasted for just twenty years. These were the most occupied of his busy life; and in justification of what we said at the outset of the multifarious nature of his occupations, we proceed to give a rapid chronological sketch of them. His career as an author began, in 1819, with an _Elementary Treatise on Mechanics_. It went through seven editions, in each of which, as Mr Todhunter says, ‘the subject was revolutionized rather than modified; and the preface to each expounded with characteristic energy the paramount merits of the last constitution framed.’ The value of the work was greatly impaired by these proceedings, for an author can hardly expect to retain the unwavering confidence of his readers while his own opinions are in constant fluctuation. In 1820 he was Moderator, and travelled abroad for the first time. In 1821 he was working at geology seriously, and took a geological tour in the Isle of Wight with Sedgwick, who had been made Woodwardian Professor three years before. Later in the year he explored the Lake Country, and was introduced to Mr Wordsworth. Their acquaintance subsequently ripened into a friendship, which appears in numerous letters, and notably in the dedication prefixed to the _Elements of Morality_. A _Treatise on Dynamics_ was published in 1823, which was treated in much the same fashion as its fellow on _Mechanics_. The summer vacation was spent in a visit to Paris for the first time, and an architectural tour in Normandy with Mr Kenelm Digby. In 1824 he took a prominent part in the resistance to the Heads of Colleges in their attempt to nominate to the Professorship of Mineralogy; and later in the year he went again to Cumberland with Sedgwick, ‘rambling about the country, and examining the strata’; visiting Southey and Wordsworth; and, in the intervals of geology, seeing cathedrals and churches. In 1825, as the chair of Mineralogy was about to be vacated by Professor Henslow, promoted to that of Botany, Whewell announced himself a candidate; and by way of preparation spent three months in Germany, studying crystallography at the feet of Professor Mohs, of Freiburg: a subject on which he had already made communications to the Royal Society and to the Cambridge Philosophical Society. This was his first introduction to Germany, in whose language and literature he thenceforward took the greatest interest.