in the fea-language, is the casing that part of a ship which is to be under water with fir-board of an inch thick; first laying hair and tar mixed together under the boards, and then nailing them on, in order to prevent worms from eating the ship's bottom.—Ships of war are now generally fleathed with copper: but copper fleathing is liable to be corroded by the action of salt water, and fomethimg is still wanting to effect this purpofe. It is very probable that tar might anfwer very well.

In the Cornish mines, copper or brafs pumps are often placed in the deepest parts, and are consequently expo-fed to the vitriolic or other mineral waters with which fome of these mines abound, and which are known to have a much stronger effect on copper than fea water. These pumps are generally about fix feet long, and are screwed together, and made tight by the interpoftion of a ring of lead, and the joinings are afterwards tarred. One of thefe pumps was fo much corroded as to render it unfit for ufc; but the spots of tar, which by accident had dropped on it, preferved the parts they covered from the action of the water. Thefe projected in fome places more than a quarter of an inch; and the joints were fo far defended by the thin coat of tar, that it was as perfect as when it came from the hands of the manufacturer. If tar thus effentially defends copper from thefe acid waters, can there remain a doubt of its pre-ferving it from the much milder waters of the fea?