364 Copper Sheathing. [Nov. 



reference to any ulterior effects. These boats were stationed in 

 Portsmouth Harbour, and the copper remained bright for nearly 

 three months, when it became coated with carbonate of lime, to 

 the rough surface of which, the confervee, always floating in the 

 summer months in Portsmouth Harbour, adhered, and these 

 soon caught other weeds ; but they were all loose, and there were 

 neither barnacles, nor any other shell-jish,nor any worms, amongst 

 them ; and it is more than probable, that the same weeds would 

 have adhered even to carbonate of copper. 



Except in harbour, there is every reason to think that carbo- 

 nate of lime could not adhere to the copper, even with excess of 

 protection, and the confervas must have been washed off in a ship 

 at sea. Copper, until it is worn in holes, corrodes so fast that no 

 permanent surface remains to which weeds can adhere ; but 

 when there are inequalities in the surface, they adhere readily 

 enough even to the poisonous oxide of copper. I do not 

 believe that any of the protectors placed upon ships are in such 

 excess as to occasion any deposit, and if they are a little posi- 

 tive, or nearly in equilibrio, the whole surface remains smooth, 

 and the adhesion of weed and shell-fish is prevented. As far 

 as the experiments hitherto made enable one to judge, the 

 requisite proportion of protecting surface to that of the copper 

 is somewhere between r ^- and ^J^, but even ^-i- will save more 

 than half the copper of the navy. 



In reply to the assertion that protected ships have returned 

 aftev short voyages perfectly foul, and the delicate insinuation 

 that Sir Humphry Davy has been amusing himself by a voyage 

 to the Baltic at the public expense, I subjoin the following note 

 to the Secretary to the Admiralty, and his answer. 



MY DEAR SIR, British Museum, Oct. 22, 1 824. 



You have seen, no doubt, a paragraph in the Times newspaper 

 of the 10th instant, stating " that vessels coppered on Sir Hum- 

 phry Davy's plan with protectors have returned after short 

 voyages perfectly foul." In the same paragraph, it is also 

 insinuated, that Sir H. D.'s late voyage to the Baltic was made 

 at the public expense. Pray allow me to ask you if these state- 

 ments, or either of them, be correct or otherwise ? 



I am, my dear Sir, your faithful servant, 



J. G. Children. 



John Barrow, Esq. fyc. fyc. fyc. Admiralty. 



MY DEAR SIR, Admiralty, Oct. 22, 1824. 



In answer to your inquiries respecting vessels coppered on 

 Sir Humphry Davy's plan with protectors having returned after 

 short voyages perfectly foul ; and whether Sir Humphry Davy 



