Removing the slaked lime of three cargoes, 30 0 0 ――――――――――― Cost first year, L.152 6 8 Deduct rods, 20 0 0 ――――――――――― Cost, second, and each following year, L.132 6 8 The complete efficacy of lime-shells in preventing dry-rot is already proved—the coasting small craft frequently employed in the carriage of lime-shells not being liable to it. All that requires to be ascertained, is the minimum quantity which will effect it; and if the expense of this quantity will greatly exceed the average loss by dry-rot in our unemployed {161} shipping. If the quantity necessary be not greater than what we have supposed—even Mr Hume himself would not consider the expense extravagant—the preservation of a line-of-battle ship not exceeding that of one of our numerous army _captains_ while lying _in ordinary_. Lime is preventive of dry-rot in several ways,—when uncombined as an antiseptic, simply by drying, from its attraction for water; by its causticity, which remains for a number of months after it is slaked, destroying organic life; and by its absorbing putrescent gases. It is not easy, without trial, to form a correct estimate of the quantity of moisture which would enter through the inside planking of a man-of-war; but were the bottom of the vessel in good condition, the pumps attended to, and external air excluded, we should consider that the moisture would not greatly exceed 60 tons of water yearly, which would nearly be required to convert 240 tons of lime-shells into dry hydrate of lime. No very great injury or inconvenience would be produced by the opening of the seams of the ceiling (the inside skin), or of the inner decks or floors, or by the warping of the plank, resulting from the contraction of the timber by the dryness; but the caulking of the main deck would require to be looked to. {162} No danger from fire need be apprehended, from the sudden slaking of a thin layer of shells, even though a leak in the main deck should occur. The thickness beyond which shells could not be suddenly slaked upon dry boards without danger of fire, might be tried. It is necessary to mention, that, though lime-shells, or dry hydrate of lime, when timber is so dry as to be liable to corruption by insects or by dry rot, is, by destroying life and increasing the dryness, preventive of this corruption; yet lime, in contact with timber for a considerable time in very moist air, from its great attraction to water, draws so much moisture from the air as to become wet mortar or pulp, which, moistening the timber, promotes its decay by the moist rot. {163} II.—NICOL’S PLANTER’S CALENDAR.