The following text may have been generated by Optical Character Recognition, with varying degrees of accuracy. Reader beware!

a Me nearness may possibly have led to its acceptance as a proved law. It is only after a vessel having increased wetted area shows less resistance (as proved on the trials of the Monitoria) that THE MarINeE REVIEW nary ship-shaped forms, and its very ; progress through the water are pecu- liar to that vessel; and in introduc- ing corrugations they must of necess-ty 'be adjusted in size and proportion to suit certain laws if the full benefit of their application is to be secured. . Tue Monrrorta IMMEDIATELY AFTER LAUNCHING; BROADSIDE VIEW. we begin to question the finality of the generally accepted law, or at all events to seek for an explanation or amplification of it. The Monitoria is in most respects an ordinary single-deck cargo steamer, with poop, bridge, and forecastle, built by Messrs. Osbourne, Graham & Co., of Hylton, Sunderland, to the order of the Ericsson Shipping Co., Ltd., of Newcastle-on-Tyne. She is 288 ft. 6 im. over all and 279. it. 6 in. B. P., 'by 39 ft. 101%4 in. in breadth molded, by 20 ft. 7% in. depth molded. Instead of the usual wall-sided shell plating, however, the. vessel has two longitudi- nal corrugations, in the form of rather flat arcs, along the outside of the hull, so that where 'these are added the breadth of the ship is increased to 42 ft. at the widest part. These two wavelike swellings, which are shown in our illustrations, extend along both sides of the hull below the load water line to about the turn of the bows and quarters, where they gradu- ally merge into the ordinary contour of the ship's lines at the ends. Sympathy Between Stream Lines and Corrugations. It has been unmistakably demon- strated that. there is great sympathy between the stream lines round the vessel and these corrugations, vary- ing proportions giving varying results. _ As the co-efficient of fineness and the contour of sections and lines nearly always vary in different ships, the stream lines created by any vessel's Accordingly, any attempt to design corrugations in a haphazard, approxi- mate fashion, without any regard to the forces involved, may or may not result in a satisfactory improvement; and it is precisely this aspect of the problem that has to be grappled with in order to produce the best condi- tions for any particular vessel. Many inventions of great value have been discredited by approximate, make- shift methods having been resorted to during trials, thus retarding scientific progress and causing injury to the advocates of new ideas. This possi- ibility was disclosed, in the course of the experimental work extending over several years, by the failure or re- duced advantages in some cases and the great success in others, clearly in- dicating that law and science were associated with the corrugated-side principle. | The corrugations, naturally, give more buoyancy to the vessel, increase the periphery of shell plating girth, and therefore augment the wetted frictional area. These conditions, of course must be considered prejudi- cial to speed if taken alone without any gain from other sources. The tank experiments, however, showed an improvement, more or less according to some hitherto' undiscovered law; and when the corrugations were prop- erly adjusted to suit a particular ves- sel, improvement could 'bé relied upon. The tests were conducted in the ex- perimental tank invented by 'the late Frank:Caws;: of: Sunderland. -The writer is aware that this tank has December, 1909 been the subject of much criticism, but his knowledge of it extends over about twelve years; and as he has been the exclusive operator since the inventor's death, the writer can only express admiration for its general scheme and reliability. For compara- tive purposes it is, in his opinion, an 'deal instrument for testing the re- sistance of ships; while the fact that the results obtained during the model experiments in connection with the Monitoria have been confirmed in the actual ship, proves that the tank used is at least as reliable as any of the larger speed tanks in existence. Diminished Bow and Stern Waves. Throughout the experiments were always accompanied by a diminished height of bow and stern wave, which appeared to point to the 'principle that the higher the disturbance the greater the resistance. Bluff ships, of course, gave a higher bow wave and absorbed more power, and it was also apparent that the fuller ships per- mitted a greater percentage of im- provement than fine-lined vessels. A wave of given length may have a height indefinitely large or small, ac- cording to the power exerted to cre- ate the wave; but if a certain horse- power is exerted to create a wave and the amplitude is restricted, the length must necessarily be increased to absorb the power. As, however, the length of wave is the measure of its speed in the ratio of 1 Length of wave O.5oF a greater speed of wave is obtained with the same energy contained in that wave. This augments the speed of the water passing the vessel, caus- ing less retardation and eddy than 'be- fore; while the bow wave is also pre- vented from attaining the height it would if the water further aft were re- tarded. This in turn favorably affects all the other froces acting round the vessel, and indeed in the tank experi- ments it was a very common occur- rence to obtain a reduced resistance equal to 10 per: cent. (and in "some over 18 per cent) of the -en- coal consumption. Cases gine power and A Subject But Partially Known. The action of water, waves, and ship resistance generally, as already indicated, are only partially known.. The subject is a very complex one, with few facts for a definite basis and much scope for generalities; and there is still much to discover 'by those who have studied the subject. The general principle of robbing the