1825.] 
the vessel was concerned. © The copper 
became. covered, with-s barnacles: and 
other. marine -animaloulz;:in @ greater 
degree. than, vessels which have the cop- 
per undefended jo. » its” 
The -act.seems to be, that the oxida- 
tion of. the copperjin the-ordinary. way, 
prevents the, adhesion of these animal- 
culz ; probably trom, its| poisonous pro+ 
perties, and,also, from: its resisting the 
depesit. of any caleareous:er, other ear- 
thy matter.|,.But when this oxide of 
copper, is,no longer formed, the surface 
of the sheathing affords what:may be 
called a.neutral ground for the resting- 
place of those marine fungi-and ‘animal- 
cule, which abound to such-a great ex- 
tent.-in all the seas of warm» latitudes. 
It has been: thought advisable, there- 
fore, from the, practical observations 
which have been made.on the agency of 
these, protecting bars of iron to:a ship’s 
bottom, to proportion their extent of 
surface (compared with that of the cop- 
per),.s0.as not entirely: to neutralize the 
chemicalj\ageney of the, copper on the 
water; but toallow, a slight or partial 
oxidation, so.as to repel the adhesion of 
barnacles, &c, in some degree. 
In consequence. of ‘this adhesion ‘of 
marine ,animalcule and. weeds to. the 
bottem.of-such vessels as have been 
protected, many persons: who have 
either a prejudice against: all improve- 
ment, or are probably» interested in 
“the old state of things,’ have not 
hesitated: to.deny the efficacy altogether 
of the method recommended by Sir H. 
Davy, for preventing the destruction of 
copper, sheathing.» But, whatever doubt 
may have been thrown on the advan- 
tages of the proposed method previously, 
must be-nearly,-if notvaltogether re- 
moyed, by the contents of a paper in 
the. July, mumber ‘of the “ Annals of 
Philosophy,” fromthe reports of two 
gentlemen whose statements cannot ‘ad- 
mit of a suspicion of want of accuracy. 
It is; stated,- that: -the Carne Brea 
Castle,’ one of»the:East-India Com- 
pany’s: ships, which bas just returned 
from Galeutta; having been brought into 
a drydock, was examined by the pro- 
prietors, Messrs. Wigram, ‘Sir H. Davy, 
and othemgentlemen ; when every part 
of her boettomwas found to be bright, 
and. free |from-adhesions of every kind. 
The, eopper-was apparently very little, 
if at, all corroded ; while the iron bands, 
which are,abont ansinch-and-half thick, 
are ‘not ao:much corroded but that they 
will.senve for ope or: two more voyages. 
Preservation. of the. Coppér Sheathing of Vessels: 
22° 
The proportion of the ‘iron -stirfuce to * 
that of the copper on this ship owas. 
from 3,5 to z45: STL Mt 
A. yacht belonging to Lord Darnley 
was also ‘protected by iron, in the pro-"” 
portion of to 735 the surface of copper," 
in the month. of May 1824. ‘And after‘? 
being employed in sailing’ during ‘the ” 
whole summer, her bottom. was found 
to be free from any kind of adhesions, 
and the copper apparently untouched, 
A few barnacles had attached them: 
selves to the iron bars, which’ were, 
however, easily rubbed off: but ‘the 
copper, was in the same: state as when 
the vessel left the dock. 
A West-India-man, belonging to Mr. 
Horsfall of Liverpool, which had been 
protected by #5 part of iron, fastened by 
copper bolts on each side her keel, was 
found, on examination, after a voyage to 
Demerara and back; to be “ perfectly free’ 
from any foulness on the copper, though” 
she lay many weeks in/a*river remark- © 
ably favourable to the adhesion of para- *- 
sitical animalculz and weeds.” pote 
=" 
Another large ship, belonging to Mr. 
Sandbach «of Liverpool, which had” 
wrought-iron bars, fastened by ‘iron “7 
spikes, on each side the keel, was over-~ 
vara; her’ copper was found perfectly 
scarcely any substances adhering to it, 
hauled. After two voyages to Deme-?~ 
free from corrosion, and) there were~ 
except a very’ few minute barnacles, ” 
y a 
near the keel, fore and aft. The iron 
spikes were, however, so much cor- 
roded, as to endanger the falling off of * 
the iron bars; consequently, copper 
bolts would be preferable for this pur- 
pose. nt 
The Dorothy, another Liverpool shi 
having made one voyage to Bombay 
and back, the owners had bars of iron, 
four inches broad and one inch thick, 
placed along ‘her keel, covering about 
one-seventieth of the surface of the cop- 
per, in order to try the experiment 
whether the copper would bear a second 
voyage to India; which can seldom be 
hazarded in the ordinary, way. The 
ship returned from her second voyage 
in May last, and, on examination, her 
copper was found to be little further 
reduced than at the end of the former 
voyage ; whilst the iron bats were re- 
duced about three-fourths of an inch in 
breadth, and from one-fourth to one- 
half inch in thickness, though most re- 
duced within a few feet of the extremit 
ties of the keel. ~The copper and iron ~~ 
are however considered to be capable” — 
rx 
u 
fot fi 
