ON NA VAL ARCHITECTURE. 289 



built about the year 1819, and was engined by Boulton and Watt. This 

 ship had two engines of forty horse-power each, to be worked in pairs 

 on the plan understood to have been introduced by this firm in 1814. 



In 1833-4 iron appears to have first come into use for the construc- 

 tion of steamships, and there are models of the "Rainbow," the 

 "Nemesis," and other vessels built soon after this date. In 1838 the 

 "Sirius" and "Great Western" commenced the regular Atlantic pas- 

 sage under steam. The latter vessel, proposed by the late I. K. Brunei, 

 and engined by Maudslay, Sons, and Field, made the passage at about 

 eight or nine knots per hour. There is an excellent model of the 

 engines of the " Great Western" in the collection. One year earlier, 

 i.e. in 1837, Captain Ericsson, a scientific veteran who is still among 

 us, towed the admiralty barge with their lordships on board from 

 Somerset House to Blackwall and back at the rate of ten miles an hour 

 in a small steam vessel, driven not by paddles, but by a screw. Messrs. 

 Laird supply a model of the " Robert L. Stockton," built by them in 

 1839, from Capt. Ericsson's designs. This vessel had the rudder be- 

 fore the screw, arranged as in the modern fast launches built by Mr. 

 Thorneycroft. This firm exhibits a model of a proposed screw ship-of- 

 war of a still earlier date, 1836. The screw did not come rapidly into 

 favour with the Admiralty, and it was not until 1842 that they first 

 became possessed of a screw vessel. This vessel, first called the 

 "Mermaid" and afterwards the "Dwarf," was designed and built by 

 the late Mr. Ditchburn, and engined by Messrs. Rennie. Her model 

 is in the exhibition. 



In 1841-3 the "Rattler," the first ship-of-war propelled by a screw, 

 was built for and by the Admiralty under the general superintendence 

 of Mr. Brunei, who was also superintending at the same time the con- 

 struction of the "Great Britain," built of iron. The engines of the 

 "Rattler," of 200 nominal horse-power, were made by Messrs. Maudslay. 

 They were constructed, like the paddle-wheel engines of that day, with 

 vertical cylinders and overhead crank shaft, with wheel gearing to give 

 the required speed to the screw. The " Rattler," built of wood, does not 

 exist now, but the " Great Britain," built of iron is still at work. 



The next screw engines made for the Royal Navy were those of the 

 "Amphion" 300 nominal horse-power, made in 1844 by Miller and 

 Ravenhill. In these the cylinders took the horizontal position, and they 



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