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The Way of a Ship Three Very Interesting Lectures by Sir John Biles at = Royal Institution of Great Britain IR JOHN BILES has recently S delivered three very interesting lectures at the Royal institution of Great Britain on general principles relating to ocean-going ships of both merchant and naval types. While no new statement has been made in connection with these, they form a very instructive summary of all that the naval architect has to bear in mind when designing a ship which is intended to go to sea in all weathers and to perform set duties. The first lecture was entitled "Smooth Water Sailing." Elementary questions of weight and buoyancy were examined, and the result of considering a ship at rest in still water was shown to be that the weight of the water displaced by the ship is equal to the weight of the ship, and the centers of gravity of the ship and the displaced water must lie in the same vertical line. When inclined to reasonably large angles from her posi- tion of rest, her form should possess sufficient stability to restore her to the upright position. She must also be made of material suitable to resist the forces due to the inequality of weight -and buoyancy at different sections of the ship, which tend to separate the parts of the structure from each other. The vessel was then assumed to' be "set in motion in still water, and the fundamental considerations of resistance and propulsion' were explained. Sir John indicated that the solution of ob- taining a..required speed from a given ship was to determine the resistance of the ship at, that speed, and to supply her with a source of power which could de- liver the force equal to this resistance at the required speed. The determina- tion of resistance is effected by separat- ing it into frictional and wave-making resistance. The first can be calculated for any ship from: known data. The 'second can only be accurately determ- ined by model experiments. An experi- mental tank is costly to build and main- tain. Fortunately, there is now available to all a tank of this kind at. the National Physical Laboratory, and its usefulness is increasing daily. As an example of this a case was quoted in which 25 per cent reduction was made in the resist- ance, and also practically another 25 per cent in the added efficiency of the pro- pellers. It will be seen, therefore, that with this tank to fall back upon no one need make great mistakes in predicting the horse-power necessary to propel al- most pth or to make designs of unusual forms. Similarly the best pro- peller for a design can be obtained from tank experiments. In touching upon the speed of ee. Sir John Biles outlined a brief history of sailing and steam ships. The first steamer to cross the Atlantic was the Savanah, in 1819; she was 145 ft. over all, 26 ft. beam, and was designed to steam at 6 knots. She actually crossed under sail. From this time to 1869 the speeds increased to about 12 to 13 1/2 knots. In 1869 they rose to 14 1/2 and 15 knots; in 1893, to 22 knots; and at the present day the Lusitania and Maur- etania reach practically 26 knots. Last year the Exmouth II was completed for the Metropolitan Asylums Board, a sail- ing ship of about the same size as the Savanah, and built with the object of training boys for sea. Sir John's re- marks on this subject are worthy of note. "It is a. pity," he observed, "that in a country which depends:so much up- on seafaring for its existence there are not many more such vessels. There is a good deal spent upon education in this country, while so little of it goes to the training of boys for the sea. There is much more real sport in taking part in the sailing of a vessel like Exmouth II than' in all of the football or cricket games that ever were played." 3 Onin Travel The second lecture dealt with the subject of "Ocean ae This was once described as 'something worse than going to prison, with the additional chance of being drowned." This chance is not now so great as being run over in the streets of Lon- don. Sir John then proceeded to point out the large increase in speed and size of ship in recent years, due to the change from wood to steel and the use of high-pressure steam, surface condensers, and turbines. The effect of waves upon the stres- ses to which ships are subjected at sea was traced, from the increase in the size of waves from a ripple to very large waves. The stresses are a maximum when the length of the wave is equal to that of the ship. In ocean-going steamers, on account of their lading, the stresses are greater when on the crest of such a wave than when in the hollow. The effect of bodily heaving of the ship into, or out of, the wave is to re- duce the stresses on the crest and increase those in the hollow. The effect of pitching is to increase the stresses at the ends of the ship. The sizes of waves at sea depend upon the stretch of water along which the wind can blow. In the North Atlan- tic 600 ft. seems to be a very long wave, and the height occasionally reaches 43 ft. It is very doubtful if a ship as large as the Imperator would ever meet waves of her length in the Atlantic, so that the stresses calculated upon the usual assumption of a wave the length of the ship and height equal to one-twentieth the length would be much greater than the actual state of affairs. That the theory underlying these stress calcu- lations is sound was proved by the experiments carried out some years ago on the torpedo-boat destroyer Wolf at Portsmouth. She was very severely tested, and the results ob- tained proved conclusively that the theory was sound. Dealing with the subject of rolling of ships amongst waves, Sir John said that "It seems a paradox that if a ship had no stability she would not roll.' The greatest rolling takes place when there is synchronism be- tween the ship and the waves. In this case only the ship's resistance to rolling can prevent disaster due to capsizing. The third lecture, on "The War Navy," dealt with the development of types of warships. The variation in interest in the navy indicated by the record of the number of men borne on the books and the total money spent. In 1816 there were 35,000 men; in 1836, 30,000; in 1856, 60,600; in 1876, 60,000; in 1886, 61,400; in 1896, 93,700; in 1906, 129,000; and to- day, 150,000. In 1816 and in 1886 the cost was 13 millions; now it is four times as much. About 25 years ago the eight chief naval powers spent 39 millions; last year they spent 167 millions, or more than four and a quarter times as much. The Victory, built in 1765, was little different from the Duke of Wellington, laid down. in 1850. In 1865 the momentous change from wood to iron had be- gun. The old wooden ships ceased to represent our naval power in the seventies of last century, but the men who designed ships' engines and guns