Captain Hairs Remarks on the Utility of Chain-Cables. $%5 
ject more firmly, the more they are pulled upon. The tails of 
these nippers might be of the usual kind, especially if the mes- 
senger were also of hemp ; and 1 have great doubts about the 
successful application of iron to this branch of the subject, where 
the risk of injury to the people employed is so great, and, as I 
think, unavoidable. It is sufficiently serious when a hemp-mes- 
senger breaks, but the breaking of a chain would sweep every man 
off the deck. It is worthy of the attention of an ingenious man 
like Captain Brown, to overcome this difficulty ; and, perhaps, 
it may be possible, by some mutual adaptation of the different 
principles of rope and iron, to place a chain in the middle of the 
messenger, like the heart in a four-stranded rope, and thus to 
gain the strength of the one, without losing the friction and the 
protecting quality of the other. 
In reply to your queries respecting the various other uses to 
which iron has been applied of late years in nautical affairs, 
I have little to say, as I fear I have already greatly exceeded 
your limits. I shall, therefore, merely allude to the most re- 
markable. These are, — spindles for capstans,— shrouds for 
masts, — bobstays and gammoning for bowsprits, — topsail-sheets 
and ties, (but this, I believe, is in the merchant service alone, 
though worthy of imitation in the Navy), oil and varnish bar- 
rels, and many minor purposes, all conducing more or less 
to the efficiency of ships having long voyages to perform. But 
one of the earliest and still the most important uses of iron, 
was the four feet cubes or tanks for holding water, a great bless- 
ing to the seafaring community. By means of this contrivance, 
water may be kept for any length of time, without the slightest 
perceptible contamination. I once filled a tank with clear water 
at Portsmouth Harbour, and having carried it four times across 
the torrid zone, and round Cape Horn, over a greater distance 
than the circuit of the globe, brought it back again more than 
two years afterwards in the same tank, not in the least degree 
discoloured, and in all respects as good as when it was first taken 
up from the spring. 
Dunglass, 
mh Aug. 18 25. 
