48 ANNUAL OP SCIENTIFIC DISCOVERY. 



three feet, with open sides below the water-line for the water to pass through, 

 and connected with the vessel by upright plates of boiler iron. Having got 

 thus far, imagine the hub of the wheel which is to be placed on the shaft 

 between the two sugar loaves to be exactly the size of the but-ends of the 

 loaves, with twelve iron flanges, or screws, fastened at equal distances on the 

 outer edge of it. It will thus be seen that the wheel forms the centre of the 

 body of the vessel, and revolves transversely ; the twelve flanges on the edge 

 of it being the propelling power. When in the water, with her engines, coal, 

 and freight, one-half of the flanges on the wheel will be all the time in the 

 water, and with ninety revolutions per minute some idea of its propelling power 

 may be imagined. The vessel has no deck ; but on the upper segment of the 

 tubular surface there are gangways, to pass downward into the two sections, 

 surrounded by iron railings, which extend on either side about thirty feet from 

 the centre. With the exception of the two smoke-pipes and ventilators, 

 these are all the outer works that will be visible. Baltimore American. 



STEEL SHIPS. 



In 1850, Mr. Ewald Riepe obtained a patent in England for certain im- 

 provements in refining steel, which consisted, mainly, in subjecting bars or 

 lumps of raw or crude steel to the action of heat for about four hours, in a 

 furnace closed to the external atmosphere, the temperature being kept a little 

 below the melting-point of the steel. By this method of operation, car- 

 buretted hydrogen and oxide of carbon are developed in the furnace in 

 abundance, while the oxygen of the air is entirely prevented from acting 

 upon the steel, the working door of the furnace, etc., being carefully luted 

 for this purpose. 



This patent, says the London Mechanics' Magazine, which was permitted 

 to remain in abe} T ance for some time, has lately been worked with very 

 beneficial results by Mr. William Clay, of the Mersey Iron Works; the steel 

 produced by means of it having been found to possess a very fine uniform 

 grain, and to be peculiarly suitable for the plating of ships. A new steamer 

 of 170 tons, named the Rainbow, intended for the Niger expedition, has been 

 recently constructed of plates of this steel, of the following dimensions: 

 Length, 130 feet; beam, 16 feet. Her engine is high pressure, and of 60 horse 

 power, woi'king up to 200 horse power, indicated; and the boilers, which 

 have also been made of Mr. Clay's steel plates, have been proved up to 200 

 pounds on the square inch, though they will only require to be worked at 50 

 pounds to 60 pounds. The advantage of employing this material over the 

 ordinary iron plates is, that, with about half the thickness, they are said to 

 give equal strength with the best iron boiler-plates, so that vessels are able 

 to be constructed of considerably lighter draft of water than formerly, a 

 result which is likely to be of incalculable benefit in the navigation of the 

 shallow rivers of Africa and India. It will be remembered that Dr. Living- 

 stone took out a small steam yacht, the plates for which were formed of the 

 patent homogeneous metal manufactured by Messrs. Shortridge and Jessop, 

 of Sheffield. The advantage claimed for the Riepc steel is, that, while pos- 

 sessing equal strength and adaptability for the purposes of ship-building, it 

 can be more economically produced. Indeed, it is said that the process of 

 manufacture is so simple, and the cost so little in excess of that of ordinary 

 iron, that, by the saving of weight in the material, as compared with iron of 

 equal strength, it will become absolutely cheaper. Apropos, of the strength of 



