Getting home at last, and having put myself to arrange materials of which it was not easy, after so much interruption, to recover the command;--which also were now not reducible to a single volume--two questions occurred in the outset, one in the section on vegetation, respecting the origin of wood; the other in the section on sea, respecting curves of waves; to neither of which, from botanist or mathematicians, any sufficient answer seemed obtainable. In other respects also the section on the sea was wholly unsatisfactory to me: I knew little of ships, nothing of blue open water. Turner's pathetic interest in the sea, and his inexhaustible knowledge of shipping, deserved more complete and accurate illustration than was at all possible to me; and the mathematical difficulty lay at the beginning of all demonstration of facts. I determined to do this piece of work well, or not at all, and threw the proposed section out of this volume. If I ever am able to do what I want with it (and this is barely probable), it will be a separate book; which, on other accounts, I do not regret, since many persons might be interested in studies of the shipping of the old Nelson times, and of the sea-waves and sailor character of all times, who would not care to encumber themselves with five volumes of a work on Art. The vegetation question had, however, at all cost, to be made out as best might be; and again lost me much time. Many of the results of this inquiry, also, can only be given, if ever, in a detached form. During these various discouragements, the preparation of the Plates could not go on prosperously. Drawing is difficult enough, undertaken in quietness: it is impossible to bring it to any point of fine rightness with half-applied energy. Many experiments were made in hope of expressing Turner's peculiar execution and touch by facsimile. They cost time, and strength, and, for the present, have failed; many elaborate drawings, made during the winter of 1858, having been at last thrown aside. Some good may afterwards come of these; but certainly not by reduction to the size of the page of this book, for which, even of smaller subjects, I have not prepared the most interesting, for I do not wish the possession of any effective and valuable engravings from Turner to be contingent on the purchasing a book of mine.[2] Feebly and faultfully, therefore, yet as well as I can do it under these discouragements, the book is at last done; respecting the general course of which, it will be kind and well if the reader will note these few points that follow.