146 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[Mat, 



radially from tlic central shaft, and at an inclination from the perpen- 

 dicular. When these hoppers are used, it will lie necessary to stop 

 the suiiplyof clay as the pistons advance to press it througli the dies: 

 this may he done hy a sliding-plate, or a valve, opening inwards, heing 

 made tu close the bottom of the liopper; or the pistons may be pro- 

 vided with a shield to sliut out the further supply of clay as they ad- 

 vance. In either case it will he requisite to stop the rotation of the 

 sweepers or arms of the pug-mill. 



INCRUSTATION OF BOILERS. 



Maximilian Fkancois Joseph Delfosse, of Regent-street, Mid- 

 dlesex, for " Impronme7ils in preventing and nmoring incrustation in 

 iftajK-ioitos."— Granted August 20, 1S4G; KuroUed February 2.% 

 1817. 



This invention consists in adding to the water used in steam-boilers 

 a mixture which acts on the precipitahle matters in the water to pre- 

 vent them forming any incrustations on the interior of the boiler, and 

 which will also remove anv incrustations that may have been jire- 

 vionsly formed. This mixture the patentee has named the "antipe- 

 trifying mixture;" it is composed of dry tannic or gallic extract, 

 hydrate ot soda, or soda deprived of its carbonic acid, muriate of 

 soda, and subcarbonate of potash. The proportions will vary accord- 

 ing to the impurity of the water, and to the boiler being stationary or 

 locomotive. If the boiler be stationary, and fed withiresh water, the 

 amount of antipetrifying mixture for 33G hours consumption per 

 horse-power maybe'made by mixing together 12 oz. of muriate ot 

 soda, 2J oz. of hydrate of soda, 2 drachms of dry tannic or gallic ex- 

 tract, and h oz. of subcarbonate of potash. For locomotive boilers, tra- 

 velling on an average about 140 miles each day, the quantity of the 

 mixture per horse-power is increased one-fifth. If the vtater be 

 brackish, or a mixture of salt water and fresh (such as the water of 

 tidal rivers), the muriate of soda is omitted, and iuste.id G oz. are used 

 for 2A oz. of hydrate of soda, and five drachms instead of two of the 

 dry tannic or gallic extract ; the mixture is also prepared in this man- 

 ner when sea-water is used in the boiler. Tlie patentee prefers in- 

 troducing the mixture into stationary boilers in quantities sufficient 

 for two, three, or more days; but locomotive and marine boilers are 

 to be supplied daily with a'portion of the mixture, corresponding with 

 the amount of duty to be performed. 



IMPROVED RAILWAY CHAIR AND SLEEPER. 



M. M. Bessas-Lamegie and Henry, of France, propose to combine 

 the ordinary railway chair and the sleeper, by forming them of cast- 

 iron in one casting, as shown in the annexed figure ; a is a cast-iron 

 plate, and b h the chairs, whicli are kept at the proper gauge by an 

 inch round wrought-iron bar d passhig through the chair, and secured 

 thereto by vertical pins c; the underside of the plates are grooved or 

 ribbed to prevent them slipping. 



HISTORV OF ENGINEEHING. 



By Sik J. Rennie, President of the Institution of Civil Engineers. 

 (^Concluded from page 119 ) 

 Iron Vessels. 

 The verv important improvement in the introduction of iron for the con- 

 struction of vessels, enables ns to combine lightness and elegance of form 

 with streiiKth and durability. For this valuable addition to marine archi- 

 tecture we are indelited to Aaron Manby. In 1820-21 he constructed at 

 Horsclcy near Birmingliam, a wrought-iron boat, called the ' Aaron Manby,' 

 120 feet long and 18 feet beam, and when laden drawing 3 feet C innlies 

 water- it was pr»pelled by Oldham's feathering paddle-wheels, worked hy a 

 linele'cncine of 80 h.p. ; and was built for the purpose of plying on the river 

 ieiiie Ihe boat was completed in 1821-22, aud was navigated across the 



Channel by the present Sir Charles Napier, who was deeply interested in the 

 underlaking ; it was not only the first iron vetsel that ever made a sea voy- 

 age, hut also the first that conveyed a cargo from London to Paris direct, 

 withuut transhipment. She contiiiueil plying between Paris and Havre for 

 several years, until superseded by other more powerful and improved boats: 

 the liull is yet in existence, and is still used with new en;;ine3 on board, as 

 are three otiiers, wliich were bnilt about the same tin^e. In 18.'i2 Maudslay 

 and Fielil built four iron vessels for the liast India Company, for the naviga- 

 tion of the Ganges, and fitted Ihem with oscillating engines, of the united 

 power of 60 horses ; tbey vi'ere 120 feet long, 24 feet beam, and drew 2 feet 

 water; they were so successful that six more were ordered shortly after- 

 wards. The use of iron, however, did not make much progress untd recently, 

 on account of the prejudices and obstacles which generally, if not invariably, 

 impede the progress of all great inventions. At present, iron is much em- 

 ployed for vessels, and promises in many cases to supersede timber. Objec- 

 tions against its general employment have been urged, on account of ths 

 bottoms of the vessels being liable to become foul on lung voyages, and for 

 the purposes of war, the splinters of the iron wlieii struck by shot are said 

 from recent experiments to be more detrimental than from wood. The art 

 of building iron vessels is, however, in its infancy, and it is very prohible 

 that further experience and investigation will, in a great measure, obviate 

 the evils. The strength, lightness, and other qualities tliat have been men- 

 tioned, give it great advantages for the construction of fast-sailing passage- 

 vessels, and the water-tight bulkheads constructed with it, give great addi- 

 tional security in case of accidents ; these water-tight bulkheads are now 

 almost universally adopted ; but the precise date and origin of their intro- 

 duction is not very clear. Captain Evans, of Holyhead, proposed them for 

 timber vessels in the year 1826, and soon after that time they were used in 

 an iron vessel constructed by Grantham for C. AV. Williams. Examples of 

 their importance have frequently occurred, demonstrating the necessity of 

 their intrcductioa into all vessels, whether for river or sea navigation. 



Screw Propelling. 



Great as has been the result of steam navigation under the paddle-wheel 

 system, still as perfection is approaching, it cannot be denied, that it has 

 several disadvantages wiien applied to sea navigation during stormy weather, 

 which it is most desirable to obviate. Paddle-wheels act to the greatest ad- 

 vantage in smooth water and upon an even keel. The unequal immersion of 

 the paddle-wheels during the rolling of the vessel, in a heavy sea, prevents 

 that uniformily in the action of the engines, which is necessary to insure 

 their greatest effect, and although lliis may be lessened, to a certain degree, 

 by the use of mechanical or feathering wheels, as I have already stated, the 

 complexity of their construction is objectionable. The resistance, offered by 

 the paddle-boxes to the wind, in addition to their top weight, has a sensible 

 influence in diminishing the speed and effect of the engines, and in ships of 

 war, the great space occupied by the wheels on the broadsides of the vessels, 

 materially interferes with the efficiency of the batteries ; moreover, the 

 wheel, as the principal propelling agent, being constantly exposed to shot, is 

 under very considerable risk of having its efficiency impaired. The idea, 

 therefore, of substituting for it some other propelling agent, had long been 

 a favourite object of investigation amongst engineers. The origin of this, 

 like every other great invention, is very difficult to be ascertained with accu- 

 racy, as the same idea not unfrequently occurs at the same time to different 

 individuals, totally unconnected with each other. The first idea of stero- 

 propelliiig was very probably suggested by the movement of fishes, whose 

 chief propelling power exists in the tail, as also from the common and an- 

 cient practice of sculling a boat from the stern. A rude idea of stern pro- 

 pelling is attributed to Duguet in 1727, but it was so totally different from 

 the system now employed, that it can scarcely be called the same invention. 

 His system consisted of two boats, connected together by two cross beams 

 with a screw, inserted between the boats ; this double boat was moored to a 

 post in the river, and the current, acting upon the screw, turned it round, 

 the motion thus generated, was communicated over pulleys, to which were 

 attached the vessels to be drawn along ; this plan may be likened to the 

 effect of a water-wheel, or any other fixed first mover ; still there is an idea 

 of the screv\-, which, if pursued, might have been converted into screw-pro- 

 pelling. In 1768 Painton proposed the pteraphore to be applied to the bow 

 and stern and sides of a vessel horizontally, but does not describe how it was 

 to be moved. Lyttlelou also proposed a screw-propeller in 1794. The first 

 practical experiment, however, appears to have been made by Shorter in 

 1802, with a propeller like the sails of a windmill, applied to the stern of a 

 vessel in the Thames. He afterwards tried several propellers, particularly 

 in the ' Superb' line-of-battle ship in Gibraltar Bay, worked by a screw by 

 the intervention of the capstans, by which the vessel was moved through the 

 water at the rate of about 2 miles an hour. 



Shorter does not describe the kind of propeller used in this experiment, 

 although Napier, who afterwards proposed a similar plan without knowing 

 what had been done, when he accidentally found Shorter, had from him an 

 account of his experiments, and saw a large coUection of propellers a;iplica- 

 ble to the bow, stern, sides, and every part of the vessel : Napier acknow- 

 ledged and admitted that Shorter had conceived almost every possible kind 

 of arrangement, and that liis models and plans comprised most of the systems 

 since made public by different parties; Shorter also exhibited several experi- 

 ments with different propellers, and attributed the best results to a propeller 

 with a single blade projecting from the axis. In 1824 a work was published 

 under the direction of the French goveruiueut, describing tlie several modes 



