NAVIGATION, used in its most general acceptation, is the art of constructing ships, as well as of manoeuvring them at sea, and guiding them, by the deductions of mathematical science, from one port to another.
This art, of so much importance in the present state of society, may be regarded under several aspects, very different from one another. In one sense it may be view ed as including the art of constructing ships of the most perfect form, for the purpose of being conducted with safety and expedition across the ocean : this branch of it is usually called and we must refer to that article for the full elucidation of its principles. In another sense it may be regarded as the art of regulat ing the motion of this noble machine by mechanical contrivances, so as to employ with the utmost advantage the powerful agents which nature has presented for transporting it from place to place. This department of navigation constitutes seamanship, under which may be included, not only the management of a ship in ordinary eircumstantes, but also the manceuvring her in the face of an enemy, either for the purpose of giving battle, or avoiding an unequal conflict. See Inland NAVIGA TION, SEAMANSHIP, SHIPBUILDING, and ../Vava/ TACTICS.
Lastly, it is the art of conducting a ship from onc port to another, so far as depends on the direction and length of the tract which she ought to pursue ; and of finding, when necessary, her geographical position on the sur face of the ocean. It is this branch of the subject which we propose to consider under the present article.
Navigation, in the restricted sense wc have attached to the term, may he said to be a branch of geography and astronomy, inasmuch as it not only borrows from these sciences its leading principles, but depends, for a detailed illustration of its various parts, on the practical applications of which they are susceptible. In the short view, therefore, which we mean to give of the history of navigation, we shall confine ourselves entirely to an ac count of the progress of the art, so far as its improve ment has been owing to the assistance which it has re ceived from geography and astronomy, aided by the light of geometry ; referring for the history of maritime discoveries to the aiticle GEOGRAPHY.
NVhile the practice of navigation was in a state of in fancy, it neither required nor admitted the application of refined principles ; for until the invention of 'he mari ner's compass no voyage could be undertaken, unless such as might be accomplished by creeping slowly along the coast, exposed to all the dangers and obstruc tions of so circuitous a course. That valuable instrn ment, which seems to have been first used for nautical put poses about the beginning of the fourteenth century, gave a new impulse to maritime enterprise, and chang ed in a short time the entire character of navigation.
Guided hy this faithful monitor, the mariner no longer confined his tract within a limited distance from the shore, but ventured boldly into the ocean, and explored his way in the darkest night, and surrounded by the most obscured sky, with a confidence and a precision hitherto unknown.
The property which the magnet possesses of attracting iron was known to the Greeks from the clays of Thales ;4 and the Chinese are said to have been acquainted with the fact upwards of live hundred years before the com mencement of the Christian era. Tho still more sur prising virtue, however, with which that 'mineral is en dowed, of assuming a particular direction when it is free ly supported on a pivot, does not. appear to have been known to the ancients ; for though Plinyt mentions several of its curious qualities with a sort of credulous enthusiasm, he does not once make the slightest allu sion to its polarity. It is difficult to determine at what epoch this singular property was discovered, but it seems to have been partially known in Europe a considerable time before the invention of the mariner's compass,f for in a work erroneously ascribed to Aristotle, but known to have existed in the 13th century, which is quoted by Vincent de Beuvais and Albertus Magnus, the polarity of the magnet is stated in terms so explicit as to leave no doubt that even at that early period it had been taken advantage of by mariners for the direction of their course. This opinion is still farther corroborated by a quotation adduced by AIontucla from a French poet, of the name of Guyot de Provins, from which it appears that the polmity of the magnet had been known towards the close of the 12th century.§ 'rhe opinion, however, which is most generally received on the subject is, that the mariner's compass was invented in the year 1302, by a native of Melphi, a town of considerable trade in the kingdom of Naples ; though the name of the indi vidual to whom mankind are indebted for an instrument which has contributed so essentially to the improvement of one of the most important arts of life, has not been transmitted by cotemporary historians. The defects of written testimony, with respect to the origin of this valuable discovery, arc but ill supplied by the conjec tures of later writers, whosc researches have done 110 thing more than to render it probable that the marinel's compass was invented, or revived, by Flavio Gioia, an obscure individual, of whom nothing is known but the place of his nativity.