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gi-avity is far from the centre of figure ; that it has a density equal 

 to 54 times that of water ; that spaces filled with plastic rock are 

 found near the surface ; that a certain amount of heat is every year 

 radiated from it into space ; and that the materials of which it is 

 composed are found, also, in the sun and stars. 



TUESDAY, MAY 4th. 



W. H. White, Esq., Assistant Constructor Royal Navy, 

 delivered a Lecture on " The Progi-ess of Ocean Steam Navigation." 



Mr. White commenced by alluding to the early attempts to 

 propel boats by steam, and traced the history of the establishment 

 of steam propulsion on inland waters, by Symington, Bell, and 

 Pulton, between 1788 and 1812. Gradually, the employment of 

 steamers became extended to the coasting trade and to short sea 

 trips. 



In 1830. steamers were first tried for carrying the mails on the 

 MediteiTanean service, and were very successful. But grave doubts 

 were still entertained as to the possibility of using them remunera- 

 tively as substitutes for sailing-ships in the Mercantile Marine. 

 This much-debated question was set at rest by the construction 

 and successful performance of the "Great Western," the pioneer 

 trans-Atlantic steamer, launched a little more than forty years ago. 

 She was considered at that time a marvel of size and of speed. She 

 was a wooden paddle-ship, length 210ft., weight (fully laden) 

 2300 tons, average speed 9 knots, coal consumed on passage about 

 500 tons. Comparing her with the '-Britannic," of the White Star 

 line, one sees the results effected by forty years' improvements. 

 The latter is an iron screw-vessel, length 450ft., weight (fully laden) 

 9000 tons, average speed in all weathers 15 knots, coal consumption 

 900 tons on the passage, or less than double that in the "Great 

 Western." 



The success of the "Great Western," however, was so great as 

 to lead to the establishment of regular lines of trans-Atlantic mail 

 steamers ; and further, within five years, the Cunard Company, the 



