The following work has engaged my utmost application for some years. Several performances on the same subject have already appeared; as Sir H. Manwaring’s _Seaman’s Dictionary_; Boteler’s _Sea Dialogues_; Guillet’s _Gentleman’s Dictionary_, and Blanckley’s _Naval Expositor_, &c. Far from exhibiting an enlarged and comprehensive view of naval affairs, these productions are extremely imperfect, according to the very circumscribed plan which their authors have adopted. There are besides, the _Dictionaire de Marine_ of M. Aubin, published in Holland; and that of M. Saverien, published in France. These are indeed voluminous, but very deficient in the most necessary articles. Besides a circumstantial detail of the local oeconomy of different marine departments, they are swelled out with astronomy, navigation, hydrography, natural history, &c. all of which are abundantly better treated in other compositions. Of the machinery of a ship; the disposition of the rigging on her masts and yards; and the comparative force of her different mechanical powers, their accounts however are often vague, perplexed, and unintelligible. With regard to her internal government in action; to the general regulations of the line of battle; and to the principal movements in sailing, they are almost totally silent. Had any of these works been executed with tolerable success, it might have rendered mine unnecessary; or probably have introduced it in the form of a translation. I acknowledge with great pleasure the advantages I have derived in the prosecution of this work, from several authors of distinguished reputation: in reality however none of those above-mentioned are of the number. In that part which is dedicated to the theory and art of ship-building, I owe considerable obligations to the ingenious M. Du Hamel. The principal pieces used in the construction of a ship, together with their combination and disposition, are copiously and accurately described in his _Elements of Naval Architecture_: and his general account of the art itself is perspicuous and comprehensive. Many of his explanations I have therefore implicitly adopted. In treating of the artillery, I have occasionally consulted _Le Blond_, _Muller_, and _Robins_, besides selecting some valuable materials from the manuscripts of officers of long experience and established reputation in that service. Whatever relates to the rigging, sails, machinery, and movements of a ship; or to the practice of naval war, is generally drawn from my own observations; unless where the author is quoted.