ite variety of instruments of the arts of war and
peace; many formed of materials, such as glass and earthenware, capable
of lasting for indefinite ages when once removed from the mechanical
action of the waves, and buried under a mass of matter which may exclude
the corroding action of sea-water. The quantity, moreover, of timber
which is conveyed from the land to the bed of the sea by the sinking of
ships of a large size is enormous, for it is computed that 2000 tons of
wood are required for the building of one 74-gun ship; and reckoning
fifty oaks of 100 years growth to the acre, it would require forty acres
of oak forest to build one of these vessels.[1081]

It would be an error to imagine that the fury of war is more conducive
than the peaceful spirit of commercial enterprise to the accumulation of
wrecked vessels in the bed of the sea. From an examination of Lloyd's
lists, from the year 1793 to the commencement of 1829, Captain W. H.
Smyth ascertained that the number of _British vessels_ alone lost during
that period amounted on an average to no less than one and a half
_daily_; an extent of loss which would hardly have been anticipated,
although we learn from Moreau's tables that the number of merchant
vessels employed at one time, in the navigation of England and Scotland,
amounts to about twenty thousand, having one with another a mean burthen
of 120 tons.[1082] My friend, Mr. J. L. Prevost, also informs me that on
inspecting Lloyd's list for the years 1829, 1830, and 1831, he finds
that no less than 1953 vessels were lost in those three years, their
average tonnage being about 150 tons, or in all nearly 300,000 tons,
being at the enormous rate of 100,000 tons annually of the merchant
vessels of one nation only. This increased loss arises, I presume, from
increasing activity in commerce.

Out of 551 ships of the royal navy lost to the country during the period
above mentioned, only 160 were taken or destroyed by the enemy, the rest
having either stranded or foundered, or having been burnt by accident; a
striking proof that the dangers of our naval warfare, however great, may
be far exceeded by the storm, the shoal, the lee-shore, and all the
other perils of the deep.[1083]

_Durable nature of many of their contents._--Millions of silver dollars
and other coins have been sometimes submerged in a single ship, and on
these, when they happen to be enveloped in a matrix capable of
protecting them from chemical cha