below it, and her timbers were covered with as many different species of the boletus as there were different kinds of wood used in her construction. All this is perfectly accordant with our theory of the dry rot; but, if our information be correct, we have much stronger proofs of its being the true one-for as soon as this unfortunate ship was closed in, stoves, strongly heated, were placed in various parts of her hold, so as to raise the thermometer to 90 degrees of Fahrenheit; an excellent hothouse was thus formed for the growth of fungus on the surface of the unseasoned timber, and it did grow most luxuriantly.

The oak timber produced in the forests of Germany is remarkably subject to the dry rot; and it is some little consolation to find that the enemy, in this respect, is no better circumstanced than ourselves. The ships in the Scheldt are known to be in a rapid progress towards rottenness. The Chatham, a 74 gun ship now in our navy, had the dry rot in her timbers when taken from the stocks in the dock-yard of Flushing. The Rivoli, just off the stocks from Venice, is also infected with the dry rot. This ship was built of timber from the forests of Dalmatia. Of English oak, that of Sussex is the closest grained and the least subject to decay; hedge row oak, or trees growing singly, less so than trees from the midst of a forest. This, too, is perfectly consistent with our theory. The more exposed trees are to the wind and sun, the more compact and durable will the timber be, while that from the dense forests of Germany and Canada, into which the sun's rays never penetrate, is more porous, more abundant in sap, and more prone to the dry rot. We may hence infer the great importance of using only well-seasoned timber in the construction of a ship.

The use of timber of the first year's fall we should most peremptorily prohibit; the vital principle, like that of seeds, will, we suspect, in every species of timber, make an effort to develop itself the first returning spring.

No discovery has yet been made, that we know of, of a speedy method of seasoning timber by artificial means, though numerous experiments have been tried with that view; such as charring, burning, stoving, burying in unslaked lime, or sand, coating with paint, tar, and compositions of various kinds, the effects of which have generally been found pernicious, by tearing the fibres asunder-or favourable to the progress of decay, by driving the moisture into the interior parts of the wood and preventing its escape.

Various attempts have also been made to destroy the principle of vegetation, by impregnating timber with some chyVOL. I. New Series,

Rr

mical preparation, as solutions of green vitriol, arsenic, acetate of lead, alum, &c. infusions of galls, common salt, &c. all of which have failed. We know not if corrosive sublimate has been tried; but we are sure, at least, that it is destructive, both of animal and vegetable life. It is well ascertained by those concerned in alum works, that the timber used in them acquires not only a great degree of durability, but becomes nearly incombustible. All processes, however, by impregnation are likely to prove too tedious and expensive to be applied on so large a scale as is required for the timber employed in ships of war. Add to this, that all acid impregnations would be destructive of iron, which is but too liable to corrosion by the acid of the woods in their natural state.

Experiments, we understand, are now making at Woolwich, on the speedy seasoning of timber, by stowing some hundred loads in a close kiln, and introducing, by means of a retort filled with sawdust, an oleaginous substance, which, by insinuating itself into the pores of the timber, as the aqueous or sappy particles are driven off by heat, prevents the fibres from being torn asunder, and preserves the logs from cracking. The idea is ingenious, but we augur no useful results from the experiments themselves. It has not been discovered, from the closest inspection, that any artificial process was adopted in seasoning the timber of the Royal William, or any other of our most durable ships; while, on the other hand, the sound state of timber found in old cathedrals, churches and mansions, after many centuries, affords the most ample proof that nothing more is necessary to secure its durability than proper seasoning, exclusion of wet and damp, and exposure to the common air. The beautiful roof of Westminster Hall is as sound and perfect as on the day it was erected. It is for those concerned in the management of timber to determine (what indeed ought not, at this late period, to be a subject of inquiry) in what mode the seasoning by a natural process may best be effected, whether by piling it in stacks, or placing it on end under sheds, or strewing it horizontally on the ground; by siding or squaring the tree when it is felled, or by leaving the outside, or sap, as it is called by the workmen, to protect the more central part from cracking.

It is not enough, however, that the timber which enters into the construction of ships be thoroughly seasoned; it should be kept as much as possible free from moisture. The alternate exposure to water and air, to heat and cold, will sow the seeds of decay in the best oak, how well soever it may be seasoned. It would be vain, therefore, to expect any very protracted period of duration in ships which, while building,

have been exposed for four, five or six years to all the vicissitudes of the weather. Yet this exposure, water-soaked at one season, split by the heat of the sun at another, and the crevices filled with ice at a third, is called seasoning! We should call it AN ADMIRABLE INVENTION FOR DESTROYING OAK TIMBER BY THE common rot IN THE LEAST POSSIBLE TIME; and the fact is, that some of the timbers which have been set up the first year, are found so far gone, in the third or fourth, as to make it necessary to replace them with others less seasoned.* Instead of six years' exposure on the stocks, with the bottom of the ship water-soaked in the cavity called the slip, and the upper part splitting in the sun, or cracking with the wind, six months would be more than sufficient to complete the machine, when the necessary quantity of dry and duly seasoned timber was collected and prepared on the spot. This, however, is not the practice; trees which have been felled a dozen years, and trees which have scarcely left the forest half as many months, greet one another in the same machine. These timbers are closed up with plank of many inches thick which must necessarily be soaked with wet, in order to bend it to the frame of the ship; and which, as it be comes dry, shrinks from its work. Mr. Pering, therefore, suggests the propriety of building ships under cover. This is not a new idea. The Swedes build all their ships of war at Carlscrona in covered docks. The slips in the naval arsenal of Venice are roofed; and the French have a covered dock at Brest. England, the first naval power in the universe, and equal to all the rest united, is most deficient in proper accommodations for its navy. Her dock-yards have risen from small beginnings to their present state, by a succession of expedients and make-shifts. The navy which they have created has altogether outgrown them; they are wanting in extent, and in the conveniences due to so magnificent a fleet. The expense of a covered dock would be doubly saved in the first line-of-battle ship built in it. The workmen would perform their work sooner and better, because no kind of weather would interrupt their progress. The ship would be calked, and painted, and coppered when dry, to the exclusion of "partial leaks, suffocated damps, and oozing drip."

But the premature decay in our ships of war is not to be ascribed solely to the state of the timber employed in their construction, nor to their being built in the open air. It is frequently owing to the mode of fastening by treenails," a mode,"

In the Nelson, a first rate, building at Deptford, some of the timbers have rents in them six feet long; these receptacles for rain and ice will, probably, before next summer, be increased to twelve feet,

says Mr. Pering, "so objectionable that I defy all the shipwrights in the kingdom, or the art of man, to invent a worse instrument for confining the planks of a ship to her side."* Though not so decidedly hostile as Mr. Pering to this "instrument," provided it be made of good sound oak of the same seasoning as the pieces which it is meant to bind together, yet we agree with him in considering it as a very im perfect species of fastening, and highly approve of the substitute which he proposes, namely, a copper bolt, of about seven eighths of an inch in diameter. Its advantages consist, in the first place, in giving a less wound to the plank and timbers, and thereby allowing a reduction of the scantling or size of the timbers; and, in the second, in giving more security, firmness, strength, and, consequently, durability to the machine. The increased expense, supposing it to amount to 2,000l. or 3,000l., or even twice as much, in a line-of-battle ship, is of very little moment, when set against the increased durability of the ship, and, above all, the increased security of her crew.

As we look on the proposed substitution as matter of no inconsiderable importance, we have endeavoured to obtain some accurate information on the subject; the result of our inquiries is as follows: that taking the number of treenails required to fasten a 74 gun ship at thirty thousand, the value of them will be about 8001. The weight of copper bolts required to replace them, may be about 45,000 pounds, which, at fifteen pence the pound, would amount to 2,8621. This additional weight, which would sink the ship in the water little more than one inch, would neither impede her sailing, nor injure her stability, as it would be principally below the line of flotation. When the ship, so fastened, is worn out, the original value of the copper cannot be reduced more than a fourth, so that the new ship, to which they may afterwards be applied, will be fastened with copper bolts at a cheaper rate than with treenails. There is already a complete establishment at Portsmouth for remelting and rolling copper sheathing. "I wish they had tried it on one ship," says Mr. Secretary Pepys, in his MS. memoirs, when copper was first proposed for sheathing ships. They did try it near a century afterwards; and though it succeeded beyond expectation, yet such were the prejudices of the surveyors of the navy, that there was but

Treenails, as the word implies, are pins of cleft oak, from an inch to an inch and a half in diameter, and from a foot to nearly four feet in length, used for fastening the inside and outside planks of a ship to the upright timbers. They have recently been made of American pitch pine, a wood more liable to dry rot and deesy than oak, and, consequently, very improper for the purpose.

one coppered ship in the whole fleet under Admiral Keppel. "We wish," in our turn, that our more enlightened surveyors could be prevailed on to try copper bolts "on one ship."

The bolts used for fastening the knees, beams, &c. are now generally of copper. The bolts of the knees and hooks, and the nails of the decks, are recommended also to be of copper instead of iron, upon the exposed parts of which, the sea air and salt water act with great power, while the acid of the wood acts still more powerfully on those that are buried within it. Whether of copper or iron, the common practice is that of clinching them by battering the ends of the bolts over metal rings. If a clinch, in the first instance, could bring all the work tight together, consisting, as it sometimes does, of three or four pieces, and from three to sixteen or eighteen feet thick, which must of course be the length of the bolts, it could not remain tight for any length of time. It would be as endless as useless to cut off the clinches and endeavour to harden up the bolts; and the ship must become more loose and leaky from day to day; as was the case with the Ocean and the Bulwark before they had been twelve months at sea.

"Let a coachmaker," says Mr. Pering, "build a coach, and fasten it together in the same way as a shipwright fastens a ship, by driving in bolts, and then clinching them on the wood: how long will that coach run over the stones in London, or on the turnpike road? But he resorts to a different mode, which is the strongest in the world, that of compressing wood into wood by means of a screw, instead of a clinch; by this all racking is done away, for a certain time, till the wood shrinks, on the observation of which the carriage is driven again to the coachmaker's, and the fastenings are hove up. Now, let any man in the world, whether he be a mechanic or not, decide which is the best mode of fastening-a clinch or a screw.". -“No bolt was ever yet driven into a ship that performed the office it was meant to do. In the first place, wood is never compressed to wood by a clinch; in the next, the shrinking of the wood gives play to the bolt-suppose the pieces forming a mast to be fastened by bolts, and the hoops left off, how long would it stand? It is the compression alone that gives it strength." Pp.

31 and 32.

The last cause of premature decay in ships, mentioned by Mr. Pering, is the mode of calking their seams. The usual practice is to begin from the upper part of the ship's side and proceed downwards. A fixed number of threads of oakum must be driven into every seam, be the width of it what it may; if too narrow to admit the quantity, the reaming iron is applied to open it; the consequence of which is, that the whole strain falls upon the plank immediately below the iron, the