INTRODUCTION.

THE reader of this little work, who shall open it with the hope of finding a complete treatise on the science and practice of Naval Construction, will be disappointed. Such an expectation would also be as unjust to the author as disappointing to himself, and the work must be judged by the circumstances under which it was written, the parties to whom it is addressed, and the views with which it is published, rather than by the pretensions which are implied in a professed treatise on Naval Construction.

The author begs the reader to consider the little book merely as the remarks of a practical sailor, written for the benefit of those of his brethren of the Naval profession who have not had time or opportunities of making them for themselves. They are some of the results of a sailor's experience concerning the practical qualities of ships, acquired during some service, and put forth after no little observation, thought, research, and experiment.

He believes that the study of the principles of construction and of the qualities of peculiar forms of ships, and of the peculiar modes of stowage, would be of great value to the practical sailor. Without due consideration to the peculiarities of a vessel's form in various parts, it is impossible justly to measure the effects to be expected from any particular trim or mode of stowage, and without a due consideration of the effect of any given disposition of weights it is impossible justly to measure the effects to be expected from any particular form-and though it may not be any part of a sailor's business to be able to

construct his own ship; yet, since different ships require the most various trim and stowage, it is indispensable, to entire success, that the commander of a ship should thoroughly understand what are the qualities due to each peculiarity of her form, and how these qualities may be modified by the arrangement of weights, in order that he may correct as far as possible the defects of form.

It was the experience of the value of such knowledge to himself as a sailor, which first led the author to the study of this subject. He began by noticing the forms of different ships, and soon remarked that each peculiarity of structure gave to each ship peculiar qualities, good and bad. A full bow gave one property; a lean run, another; a bow full at one place, gave a different quality from a bow full at another place; with an after-body comparatively full a ship steered well, and with an afterbody comparatively fine, but in the wrong place, she would hardly obey her helm.

The observations thus made were practically confirmed by observing the effect of alteration of trim, which, in fact, by taking one part of the ship out of the water and putting another part in, may amount to a practical variation of the shape of the ship. When to these experiments the author was enabled to add observations on the working qualities of his ship, on her stiffness under canvass, on her stability in smooth water, or her instability in a sea way, he very soon found, that for the efficiency of our Naval service, it was quite as desirable that the sailor should know how to bring out the useful qualities of a ship, as that the Naval architect should understand how to confer them. Further, it is difficult to conceive, that the sailor will know how or what to observe, unless he have some knowledge of the principles which guided the construction of the vessel whose qualities are to be

observed, or that having observed, he will be able to assign the good or ill effects to their true causes.

After having made such practical observations as every sailor is able to make in the course of a few years service, provided only he will direct a reasonable share of attention to the subject; connecting always in his mind the form of the ship with her performance: the author directed his attention, to the study of such works as should enable him to explain his practice by Naval science, and connect the results of his experience with the received principles of Naval Construction. In these researches he regrets to say, that he has not always been successful. So much of Naval Construction as may be most useful to the sailor, is not concisely given in any work of easy access; the study of Naval Architecture has, in this country, been condemned by the highest Naval authorities, and has, along with the school of Naval Architecture, been officially "put down ;" information on such subjects is therefore not easily to be had.*

The endeavour to supply, in some measure, the want which the author has experienced himself, was one object of the following papers, which were originally in the form of Lectures delivered to an assemblage, consisting mostly of members of his own profession.

In the first place is shewn what are the several qualities essential to an effective ship of war, and what are the peculiarities of form with which each of them in practice appears to be associated. For this purpose the forms of individual and well known ships, with their attendant qualities, are discussed.

Since these Lectures have been delivered, a Board of Reference has been established, which must be a subject of rejoicing to every real well-wisher to the country and service, who is capable of understanding the necessity which existed for such.

In the next place, it is shewn that the advantage which might be derived from any given form, may be lost and counteracted by an improper distribution of the weights in a ship, and the principles are considered, by which the stowage of a ship should be regulated in order to develope the good, and mitigate the bad qualities pertaining to its form. Here also the principles are deduced, from the consideration of practical cases in well known ships, and the serious evils which have resulted from ignorance or bad judgment in the stowage or construction of our ships of war are pointed out.

Before concluding these introductory remarks, the author desires to prepare the reader for the fact of his having ventured to adopt and to advocate, especially towards the latter part of the book, a principle of Naval Construction, which has not yet received the sanction of general consent, that which is called the wave principle of construction. The reason why the author adopted that principle is such, that though it may not convince the reader of the soundness of his judgment in this matter, it will at least acquit him of the charge of rashness or presumption in bringing it forward. It is simply this, that after having brought together all the undoubted facts of his own professional experience, and all he could obtain of other people's, he found no other theory capable of fully explaining them but the wave theory; and after having ascertained what are the peculiarities of form which have practically given the best qualities to ships, he found no other form capable of uniting together in the best proportions all the desirable qualities but that form which is called the wave form.

In the latter part of this work, the peculiarities of the wave form are described. In regard to steam vessels, it has already been extensively employed by the author