entirely new to all my acquaintance, and as I do not know that any thing of the kind has ever before been presented to the public, I am induced to think it may not be unacceptable.

DESCRIPTION of the INSTrument.

See Plate XIV.

The instrument consists simply of a screw A, Fig. 1, with a small hole drilled through its centre. The head of the screw is formed into two strong horns, for the more ready admission of the lever by which it is to be.turned. B, represents a wire, for the purpose of occasionally clearing the touch-hole previous to the introduction of the quick-match.

Fig. 2, an auger proper to bore holes, to receive the charge of the screw.

Fig. 3, a gauge, to make an entrance for the auger.

Fig. 4, a lever, to wind the screw into the wood, with a leather thong C attached to it, in order to fasten it occasionally to the screw, to prevent its being lost, a circumstance which does not often occur; for in all my experiments, when the wood has been tolerably sound, I have always found the screw left fixed in one side of the divided mass.

A roll of twine is to be steeped in a solution of nitre, for the purpose of a quick-match, or train, to discharge the powder, by thrusting a piece thereof down the touchhole after taking out the wire B.

When a block of wood is to be broken, a hole is to be bored with an auger, of a proper depth, and a charge of gunpowder introduced. The screw is to be turned into the hole till it nearly touches the powder; a quick-match is then to be put down the touch-hole till it reaches the

charge,

charge. The piece of quick-match is about eighteen inches in length, which affords the operator an oppor tunity of retiring, after lighting it, to a place of safety.

The first that was made was for J. Lloyd, Esq. of St. Asaph, the late member for Flint, who, having a great quantity of timber on his estate, considers it as a great acquisition; and at Overton Hall, last summer, spoke so favourably of it, in my presence, to Sir Joseph Banks, that he immediately sent for his smith, and requested I would give him the necessary instructions for making one; but as I left that part of Derbyshire soon after, I had not an opportunity of seeing it finished. Since my return home I have had several made, better finished, and with sharper threads, than smiths in general have an opportunity of giving them.

Dear Sir,

Letter from Mr. LLOYD.

After you left us last autumn, at Sir Joseph Banks's, his smith, who is a remarkably good workman, bestowed much needless time and trouble in making a blastingscrew; for he finished it in the highest style of polish, and, I think, made the thread of the worm too fine, or at least finer than was needful. However, it answered most completely, and very much to Sir Joseph's satisfaction, who lamented he had not seen such a contrivance many years ago, when a relation of his used to amuse himself with splitting the roots of trees, &c. in the common way. I have used the blasting-screw, for so I shall call it, all the last and preceding winter with the greatest success, and have gained many loads of fuel, which otherwise would have been suffered to rot, as the expense and labour in clearing the roots in the ordinary way renders the

fuel

fuel so procured too expensive; and since I have had the screw, 1 have observed some hundreds of roots in a rotting state in other places, from the want of knowing that there was such a contrivance as the screw.

When I was at Overton, some pieces of very tough, knotty, close-grained oak were picked from the timberheap, for the use of the Gregory lead-mine, by Sir Joseph Banks's direction, and the screw severed some pieces four or five feet in length, and nine or ten in diameter, throwing them some feet asunder, to the surprise of the miners, who were assembled on the mine-bank. Sir Joseph took the screw with him to Revesby-Abby, in Lincolnshire, where I understand he had some large roots that had lain by many years as useless; and I dare say he will give you a good account, and bear testimony to the utility of the invention. We have used it without a single accident; but my neighbour, Lord Kirkwall, having procured one to be made by that which I had from you, one of his servants, in his lordship's absence, I presume, put too much powder into the hole, and the screw was blown as high as a one-pair-of-stairs window, and passed through it into an apartment where a person then happened to be, but without any farther mischief than the loss of a pane of glass. Any one who uses the instrument will soon learn what depth of screw will be sufficient to split any root in proportion to its strength, taking care that the screw has sufficient hold to resist the force of the gunpowder before the root is cleft. I think much pow→ der may be saved by using a cotton match, impregnated by a solution of saltpetre, or any of the combustible matters generally made use of in fire-works; and by the use of the cotton the hole through the screw may be lessened, which will add to the action of the confined pow, VOL. II.-SECOND SERIES. Y y

der

der; though a straw filled with powder, in the manner in which the miners use it, answers very well. Should any one be timid in using the screw, a chain or rope may easily be attached to the screw, and that fixed to any log, or fastened to a stake driven in the ground. If wood is rotten, the screw cannot act. I assure you, that when I go abroad I constantly see great quantities of roots in a rotten state, about almost every farm-house, which would not be the case if the utility of the instrument was made public. I am, &c.

Wigfuir, Murch 26, 1802.

J. LLOYD.

Method of securing Beams or Girders of Timber, decayed by Time, or injured by the Dry - Rot.

By Mr. JAMES WOART, of Fulham.

With Two Plates.

From the TRANSACTIONS of the SOCIETY for the Encouragement of ARTS, MANUFACTURES, and COMMERCE.

A Bounty of Ten Guineas was voted to Mr. WOART for this Invention.

WHERE the ends of the girder are decayed by time,

or injured by the dry-rot, they are often taken out, and new ones put in their place, at a great expense; and if the dry rot is in the walls, the ends of the new girder will be in danger of it again: such was the case at Eltham, in Kent, where in one house there were three new girders to one floor in the space of twenty years; whereas my method will be found infallible, executed at much less expense, and not subject to the dry-rot, because the end

of