As there are abundance of books professedly written on astronomy, and the theory of navigation, I have totally omitted the terms of the former, as foreign to my plan; and slightly passed over the latter: because no reader could acquire a sufficient idea of those sciences from so partial a description. Many of the least important parts of a ship, as well as of her rigging, are very generally defined. To explain the track of every particular rope, through its different channels, would be equally useless and unintelligible to a land reader: to mariners it were superfluous: and even the youths who are trained to the sea, would reap little advantage from it; because their situation affords them much better opportunities of making these minute discoveries. I have in general endeavoured to give the etymology of the most material expressions, unless when their evident analogy to common words rendered this unnecessary. Many reasons may be alledged for introducing the French sea-terms and phrases; particularly that obvious one, of understanding their pilots, when we may have occasion for their assistance. Wherever it was found necessary to explain one technical term by another, the latter is usually printed in italics the first time it is mentioned; so that the reader may refer to it for a further explanation. As the plates of this publication were intended to illustrate the various objects to which they refer, they are little ornamented; but have in general the recommendation of simplicity and geometrical truth. In this part I have been particularly favoured with many original drawings, which are usually considered amongst the inaccessible _arcana_ of ship-building. They are much more numerous, useful, and correct, than what has hitherto appeared in any work of the kind. In fine, I have endeavoured, to the best of my judgment, to retrench the superfluities, and supply the deficiences of former writers on the same subject, as well as to digest and methodise whatever appeared loose or inaccurate therein. This undertaking was first suggested to me by my worthy and ingenious friend George Lewis Scott, Esq; who considered it as a work of extensive utility, Indeed, in a country whose principal sources of strength are derived from the superiority of her marine, it is evidently wanted. I have the pleasure also to know that Sir Edward Hawke, and several officers of respectable abilities in our navy, are of the same opinion. To this may be added, what the celebrated M. Du Hamel lately observed, in a letter to me, _s_. I mention this expressly, because some sea-officers have considered the work unnecessary. It is however submitted, with all possible deference, to superior judges; to men of science and letters, who know the difficulty of explaining the parts of a mechanical system, when the readers are unacquainted with the subject. [Illustration] A LIST of the SUBSCRIBERS.