the preservation of metals hy electro-chemical means, 343 
Had these vessels been at rest, I have no doubt there 
would have been adhesions, at least in Portsmouth or Sheer- 
ness harbours, where the water is constantly muddy, and 
where the smallest irregularity or roughness of surface, 
from either wear, or the deposition of calcareous matter, or 
the formation of oxides or carbonates, enable the solid matter 
floating in the water to rest. There is a ship, the Howe, 
one of the largest in the Navy, now lying at Sheerness, which 
was protected by a quantity of cast iron judged suflicient to 
save all her copper, nearly fifteen months ago. She has 
not been examined ; but I expect and hope that the bottom 
will be covered with adhesions, which must be the ease if 
her copper is not corroded ; but notwithstanding this, when- 
ever she is wanted for sea, it will only be necessary to put 
her into dock for a day or two, scrape her copper, and 
wash it with a small quantity of acidulous water, and she 
will be in the same state as if newly coppered. 
At Liverpool, as I am informed, several ships have been 
protected, and have returned after voyages to the West 
Indies, and even to the East Indies. The proportion of pro- 
tecting metal in all of them has been beyond what I have 
recommended, to ^ ; yet two of them have been found 
perfectly clean, and with the copper untouched after voyages 
to Demarara ; and another nearly in the same state, after 
two voyages to the same place. Two others have had their 
bottoms more or less covered with barnacles ; but the pre- 
servation of the copper has been in all cases judged complete. 
The iron has been placed along the keel on both sides ; and 
the barnacles, in cases where they have existed, have been 
generally upon the flat of the bottom ; from which it may 
