Besides those above-mentioned there were a great many subjects which he took up out of sheer interest in the investigations. For it may fairly be said that every subject of a distinctly practical nature, which could be advanced by mathematical knowledge, had an interest for him: and his incessant industry enabled him to find time for many of them. Amongst such subjects were Tides and Tidal Observations, Clockwork, and the Strains in Beams and Bridges. A certain portion of his time was also given to Lectures, generally on current astronomical questions, for he held it as his duty to popularize the science as far as lay in his power. And he attended the meetings of the Royal Astronomical Society with great regularity, and took a very active part in the discussions and business of the Society. He also did much work for the Royal Society, and (up to a certain date) for the British Association. All of the foregoing matters are recorded pretty fully in his Autobiography up to the year 1861. After that date the Autobiography is given in a much more abbreviated form, and might rather be regarded as a collection of notes for his Biography. His private history is given very fully for the first part of his life, but is very lightly touched upon during his residence at Greenwich. A great part of the Autobiography is in a somewhat disjointed state, and appears to have been formed by extracts from a number of different sources, such as Official Journals, Official Correspondence, and Reports. In editing the Autobiography it has been thought advisable to omit a large number of short notes relating to the routine work of the Observatory, to technical and scientific correspondence, to Papers communicated to various Societies and official business connected with them, and to miscellaneous matters of minor importance. These in the aggregate occupied a great deal of time and attention. But, from their detached nature, they would have but little general interest. At various places will be found short Memoirs and other matter by the Editor. (2) All of his Annual Reports to the Board of Visitors are attached to his Autobiography and were evidently intended to be read with it and to form part of it. These Reports are so carefully compiled and are so copious that they form a very complete history of the Greenwich Observatory and of the work carried on there during the time that he was Astronomer Royal. The first Report contained only four pages, but with the constantly increasing amount and range of work the Reports constantly increased in volume till the later Reports contained 21 pages. Extracts from these Reports relating to matters of novelty and importance, and illustrating the principles which guided him in his conduct of the Observatory, have been incorporated with the Autobiography.