[2] According to the calculation of Mr. Chatfield, of Her Majesty's dockyard at Plymouth, in a paper read before the British Association in 1841 on shipbuilding. [3] The phrase "wooden walls" is derived from the Greek. When the city of Athens was once in danger of being attacked and destroyed, the oracle of Delphi was consulted. The inhabitants were told that there was no safety for them but in their "wooden walls,"--that is their shipping. As they had then a powerful fleet, the oracle gave them rational advice, which had the effect of saving the Athenian people. [4] An account of these is given by Bennet Woodcraft in his Sketch of the Origin and Progress of Steam Navigation, London, 1848. [5] See Industrial Biography, pp. 183-197, [6] The story is told in Scribner's Monthly Illustrated Magazine, for April 1879. Ericsson's modest bill was only $15,000 for two years' labour. He was put off from year to year, and at length the Government refused to pay the amount. "The American Government," says the editor of Scribner, "will not appropriate the money to pay it, and that is all. It is said to be the nature of republics to be ungrateful; but must they also be dishonest?" [7] Memoirs of the Life and Services of Rear-Admiral Sir William Symonds, Kt., p. 332. CHAPTER III.[1] JOHN HARRISON: INVENTOR OF THE MARINE CHRONOMETER. "No man knows who invented the mariner's compass, or who first hollowed out a canoe from a log. The power to observe accurately the sun, moon, and planets, so as to fix a vessel's actual position when far out of sight of land, enabling long voyages to be safely made; the marvellous improvements in ship-building, which shortened passages by sailing vessels, and vastly reduced freights even before steam gave an independent force to the carrier--each and all were done by small advances, which together contributed to the general movement of mankind.... Each owes all to the others. The forgotten inventors live for ever in the usefulness of the work they have done and the progress they have striven for."--H. M. Hyndman. One of the most extraordinary things connected with Applied Science is the method by which the Navigator is enabled to find the exact spot of sea on which his ship rides. There may be nothing but water and sky within his view; he may be in the midst of the ocean, or gradually nearing the land; the curvature of the globe baffles the search of his telescope; but if he have a correct chronometer, and can make an astronomical observation, he may readily ascertain his longitude, and know his approximate position--how far he is from home, as well as from his intended destination. He is even enabled, at some special place, to send down his grappling-irons into the sea, and pick up an electrical cable for examination and repair.