16. Pursuing this idea, he applied successively to the governments of several states and kingdoms for patronage to enable him to test its correctness; and having, at length, succeeded in obtaining three small vessels, with the necessary equipments, from Ferdinand and Isabella, sovereigns of Arragon and Castile, he proceeded on his proposed voyage, which resulted in the discovery of the American continent.
17. These two great discoveries gave another powerful impulse to navigation; and inventions and improvements multiplied in rapid succession. The learned and ingenious, who at different times have turned their attention to the subject of navigation, have supplied the mariner with various means, by which he can direct his course on the deep with accuracy and certainty.
18. The instruments now employed in navigation, are the mariner's compass, the azimuth compass, the quadrant, the sextant, the chronometer, the half minute-glass, the log, and the sounding-line. In addition to these, the general navigator needs accurate maps and charts, lists of the latitude and longitude of every part of the world, the time of high water at every port, and a book of navigation, containing tables, to aid him in performing various calculations with facility; and, with a view to calculate the longitude by observation, he should be furnished with the Nautical Almanac, containing the places and declinations of the fixed stars and planets, and especially the distances of the moon from the sun and other heavenly bodies.
19. The mariner's compass, as has been before observed, is employed to indicate the various points of the horizon; but the magnetic needle varying more or less from the exact northern and southern direction, the azimuth compass is used, to show the degree of that variation. The quadrant and sextant are employed to ascertain the altitude and relative position of the heavenly bodies, that the mariner may determine the latitude and longitude in which his vessel may be. The chronometer is nothing more than a watch, designed to measure time with great accuracy. This instrument is used to determine the longitude.
20. The log is used for ascertaining the velocity of the ship on the water. It consists of a quadrangular piece of wood, eight or nine inches long, to which is attached a small cord, having knots in it, at proper distances from each other. In the application, the log is thrown upon the water, where it will not be disturbed by the wake of the ship; and the cord, being wound upon a reel, passes from it as fast as the vessel moves in the water. The number of knots, which pass off every half minute, indicates the number of miles which the ship sails per hour; hence, in nautical language, knots and miles are synonymous terms. The sounding-line is a small cord, with several pounds of lead of a conical figure attached to it; and is employed in trying the depth of the water, and the quality of the bottom.
21. Navigation is either common or proper. The former is usually called coasting, as the vessel is either on the same or neighboring coast, and is seldom far from land, or out of sounding. The latter is applied to long voyages upon the main ocean, when considerable skill in mathematics and astronomy, together with an aptness in the use of instruments for celestial observations, are required in the captain or master.
22. The application of steam to the purposes of navigation, is one of the greatest achievements of modern science and art. The great utility of this agent is particularly conspicuous in our vast country, where large rivers and bays and mighty lakes are numerous, and where an energetic people and an active commerce require a rapid intercommunication. Steamboats are but little used on the great oceans; as merchandise can there be more cheaply and safely transported in vessels propelled by sails. Since the year 1839, two lines of steam packets have been running regularly between this country and Great Britain. They commonly occupy, in crossing the Atlantic, between twelve and fifteen days.
23. The chief obstacle to the employment of steam, in long voyages, arises from the difficulty of generating a sufficient quantity of this agent, with the fuel which could be carried without overburdening the vessel; but a remedy for this inconvenience will probably be found, in improvements in the construction of steam-generators.
24. The power of confined steam acting by its expansive force, was discovered by the celebrated Marquis of Worcester, about the middle of the seventeenth century; but the first working steam-engine was constructed in 1705, by Thomas Newcomen, a blacksmith of Dartmouth, Devonshire, England. About the year 1769, James Watt, a native of Glasgow, added a great number of improvements of his own invention.
25. Steam navigation was first suggested in England, in 1736, by Jonathan Hulls. It was first tried in practice in France, in 1782, by the Marquis de Jouffroy, and nearly at the same time by James Rumsey, of Virginia, and John Fitch, of Philadelphia; but it was first rendered completely successful at New-York, in 1807, by Robert Fulton.