cluding the shield, the steam-engine, and a powerful pumping-apparatus, was not more than 126,7401., including both accidents, instead of 240,000l., as your correspondent asserts it. Adverting farther to the benefit which will result from the work by uniting populous districts, his Grace added, that "men cannot but see the great political, military, and commercial benefits that will be derived from the example of such a work, in this and in other countries; that the accidents which have occurred have demonstrated the practicability of the enterprise, and the genius and the ability of the engineer who has conducted it they have also proved this, that the work of itself is excellent, &c."

This same correspondent remarks, that if the engineer had gone deeper with his tunnel, he would have avoided all difficulties and accidents. Now were he to refer to the reports of those engineers already alluded to, who operated between the years 1803 and 1808, he would find that they could not venture lower than 76 feet which fact he will find to be confirmed by well-sinkers, who have opened wells near the river on the south side; and further, he may be informed, that eminent geologists have warned Mr. Brunel of the probable effects of the 50 feet bed of blowing sand existing below that depth, and that they recommended him to keep as near as possible to the river as, perhaps, the enemy least to be dreaded.

Notwithstanding the public acknowledgment by the Duke of Wellington of the utility of the undertaking, and of the national honour which is attached to its completion, and notwithstanding the con fidence which even the most disastrous accidents have inspired in the plan, by which one half, or nearly, of the undertaking has been realised and carried to the deepest part of the river, another correspondent or contributor of yours in No. 626, subscribing himself Fanqui, excited evidently by some grievous disappointment, protests against the enter prise, premising with an eulogical preface on the present member for Berkshire for his manly exposure in the House of Commons, of the pretended manœuvres of the patrons of the Thames Tunnel in obtaining 270,000l. from the Government. This critic unhesitatingly affirms, that the work, "if ever finished, will only be a monument of folly and absurdity, because

no vehicles of any description will ever use it as a means of transit." And he concludes by asking," who were the three most eminent engineers who had examined the plans of that scientific engineer, Mr. Brunel?"

The charge of folly and stupidity certainly possesses some novelty to those who have been taught to value the benefit of good communications across a large navigable river, as the Thames is all the way from Lou ton Bridge to its mouth, where a permanent land communication cannot possibly be obtained. But to his question. It may be replied, that the Duke of Wellington was the first eminent engineer who, as far back as the year 1820, had examined the plan, and who from that time to the present has continued to manifest great interest in its application. The late Dr. Wollaston may be considered the second who expressed himself most favourable to the plan, and, it may be added, that the name of Wollaston stands the first in the enterprise, and most prominent, not only in the list of subscribers, but of proprietors to this day. In Mr. Donkin may be found the third, a gentleman who, from his practical knowledge of machinery, was fully competent to judge as to the efficiency of the shield after he had examined it.

I cannot but give a specific denial to the assertion, that the speculation was one of those which take their date from the eventful years of 1825 and 1826, because the first meeting, convened by the friends of the enterprise for organising a company, took place in December, 1823, and the subscriptions were made up at a General Meeting in February, 1824. Should your correspondent not be satis fied with the testimonies already adduced, we may refer him to a leading article in the Times, at that period conducted by the present member for Berkshire. The article in question is dated 4th July, 1828; consequently, after the two eruptions of the river. It is therein said, that "the Thames Tunnel is an undertaking of the highest national importance and credit, and such as ought to meet with the most ample public support in extricating it from its difficulties, and rendering it a proud monument of national utility and honour."

We may conclude, by informing your numerous readers and the public, that

this national undertaking is in progress towards that anticipated achievement; and we may, on the best authority, add, that the front of the excavation has been worked and advanced several feet, and the ceiling of it raised in equal propor

tion; the whole having been done with perfect safety; and, moreover, that a considerable part of the old shield has been removed, and some portion of the new one has been put up.

Mr. Editor,-On the supposition that if a plan, however simple, contains usefulness enough in it to make it but once successfully applied, it is worthy of publicity, I beg your insertion of the following:

There is nothing novel in taking advantage of the pitching or rolling motion of a vessel, or of that derived from her way through the water, for the production of a power to work pumps; with that view, various modes have been suggested and patented; but I have never heard of any plan to make available the

steady heeling of "a vessel in smooth water. Now, having been in a situation at sea where the following simple method of freeing a ship from water by her heeling merely, would have been most desir able, had I not been otherwise relieved, I the more freely offer it to the public.

The midship section of the vessel, to which I allude, was about the form of fig. 1. She had sprung a leak, and in heeling I frequently saw the water in the lee bilge as high as the deck; when ir occurred to me, that if that body of water were withheld in a water-tight case,

it would, when the vessel was on the other tack, be emptied on the lee-side, giving her, at the same time, the advantage of greater stability, whilst the weight of water preponderated to windward; thus, at least, making up for the loss of stability she would otherwise have sustained by a constant weight of water to leeward.

In a flat vessel, like that of fig. 1, one of these cases, CC, on each side, would suffice, as they would empty themselves when the vessel's heel exceeded 14°; but in a deep vessel, as in fig. 2, two of these cases on each side would be re

quired; the water would then be emptied when the vessel's heel exceeded 11o, whether by the conduit-pipes, AA AA, or by those represented in both figures by the dotted lines; which ever of the two modes should be considered the most convenient for adoption at the moment.

This plan is by no means proposed for general adoption, as the cases which should be very long to contain much water, would take up some valuable room

in the vessel, but only as a make-shift plan in such a case as a vessel's making imore water than her crew could conveniently clear her off, without their being able to discover and stop the leak; and, as in my case, obliged to make good a point to windward, though able to procure materials (slight deals would do) to make the cases and conduit-pipes or troughs. The latter may enter the cases either below with valves or above without them. The plan, in my opinion, is most adaptable to river barges, which are constantly tacking in blowing weather, and are often leaky. It would also be worth while considering, whether the plan might not be usefully applied to channel buoys to clear them of any leakage, as being a species of pump least likely to get out of order by time or usage than any other. Having, I trust, given sufficient explanation of my ideas for comprehension,

I remain, Mr. Editor,

Your obedient servant,

6.

a cast-iron water-valve, B, attached to the main-pipe by bolts and nuts; at the bottom of the valve a small pipe, C, of either copper or lead, with a cock at D, is connected with the bottom of the valve. To shut off the gas, the cock, D, is closed, and two or three quarts of water are poured into the funnel, E, at the end of the small pipe; when the water reaches the dotted line, F, the gas is prevented from passing through the valve.

In order to open the valve, the cock, D, is opened, which lets the water out of

the valve as low as the level of the cock; and so long as the cock remains open, the valve becomes a water-trap, and lets out at D any water that may have got into the main-pipes. At the same time, the gas is prevented from escaping, by the water in the small pipe being below the level of the cock.

The above-mentioned valves were made by Mr. John Onions, of Broseley. I am, Sir,

Your most obedient servant,
PETER HORSMAN,
Secretary Mechanics' Institution.

Shrewsbury, Oct. 3, 1835.

IMPROVEMENTS IN STREET-PAVING.

Mr. Editor, Who first hit upon laying serrated carriage-way pavement is not exactly known. It is said to have been laid in Paris, in some of the towns in Normandy, in Ramsgate, Bristol, and Liverpool, before it was tried in London.

Its advantages are, the affording better foot hold to horses in ascending, and giving them confidence in descending, hilly grounds. Its disadvantages may be, the more rapid wear of the stones, and the consequent additional expenditure; the risk of horses stumbling as they descend; the chance of every joint, in frosty wea ther, forming a ledge of ice; and the insecure footing which its asperity causes to foot-passengers in crossing.

It is reported that Mr. Freeman, of Millbank-street, claims the credit of its invention. Mr. John Watson, of Ramsgate, is understood to prefer his claim. Perhaps our lively neighbours may really be entitled to the honour.

There has been another sample of carriage-way pavement, adapted for rising ground, laid down upon Fish-street-hill, formed by inserting narrow slips of York stone in the joints, so as to keep the granites about an inch and a half apart. In this mode the angles of the pitchers are more protected, and they may wear longer.

Time and observation will show which is best adapted for public use. I am, Mr. Editor, Your very obedient servant,

Oct. 13, 1835.

Q.

Sir, I do not intend to enter into a controversy relative to the utility of the new method of street-paving on inclina

tions; the public will soon find out whe ther it is or is not both useful and beneficial. The object of my addressing you is merely to state, that I am the inventor of the method, and forwarded it to Mr. Richard Lambert Jones (by the hands of the Deputy-Chairman of these works, Sir William Curtis, who obligingly undertook to put the plan into his hands), for the purpose of being used in those places in the city of London which might require it. Mr. Jones then introduced it to the notice of the Commissioners of Sewers, who have tried it with success on Fishstreet-hill and on Snow-hill; and I hesi tate not to assert, that it will be found equally so on Holborn-hill. Therefore, the fears of some of your correspondents will not be realised.

I am, Sir, your obedient servant,
JOHN WATSON,
Superintendent of the Works.

Royal Harbour of Ramsgate,
Oct. 20, 1835.

MR.

FIRE PROOF BUILDINGS. BY CHRISTOPHER DAVY, ARCHITECT. (In continuation from p. 23.) Lord Stanhope's Experiments. In the communication that preceded my last, mention is made of two extensive experimental buildings erected by Lord Stanhope at Chevening-place, Kent. One building secured according to the plan that I have given in detail (namely, by extra lathing and double intersecuring), was filled (in the lower part) completely with shavings and faggots, mixed with other combustibles, and fired. The heat was so intense that the glass of the windows was melted, "like so much common sealing-wax," yet the flooring-boards of the room (16 feet x 26) were not burnt through, nor was one of the side timbers, flooring-joists, or ceiling-joists, damaged. in the smallest degree, and the persous who went into the room immediately over the one filled with fire, did not perceive any ill effects from it whatever; even the floor of the room being perfectly cool during the enormous conflagration immediately beneath. The unsecured building was, with the mass of combustibles that it contained, set on fire after the first experiment. The height of the flame was no less than between 80 and 90 feet from the ground, and the grass upon a bank 150 feet from the fire was entirely scorched, yet the secured wooden build

ing quite contiguous to this vast heap of fire was not at all damaged, except some parts of the outer coat of plaster work. His Lordship observes:-"This experiment was intended to represent a wooden town on fire; and to show how effectually, even a wooden building, if secured according to my method, would stop the progress of the flames on that side, without any assistance from fire-engines, &c." On the same occasion the experiment was made of attempting to burn a wooden staircase, secured according to the simple method of underflooring. The under side of the staircase was "extra lathed;" several very large kiln-faggots were laid and kindled under the staircase, but it resisted, as if it had been fire-stone, all the attempts that were made to con

sumé it.

Lord Stanhope continued to prosecute his inquiries for a considerable period after the results of these experiments became known; and eventually the Association (before alluded to) determined to give his plan a trial. A house (No. 5, Hans-town) was secured by plaster, according to the directions given by Lord Stanhope, in his paper read to the Royal Society. The composition used was similar to that before described; the experiments took place as follows:

:

August 2, 1792.-At forty minutes after two-o'clock, a fierce fire was lighted on the flooring-boards, and against the ashlering in the front-garret, which bad been secured and finished as usual for habitation; the fire was kept up by a continual accumulation of fuel till forty minutes after three o'clock, when it was extinguished. At this time the skirtingboard was burnt through, as far as the fire or fuel was in contact with it, but no farther; the flooring-boards for the same extent were charred nearly through, and one piece of quarter in the ashlering was charred; but there was no appearance which could give the Committee reason to suppose the fire would have spread had it not been extinguished. At the same time a fierce fire was lighted on the floor in the back-garret, and against the ashlering (both of which had been secured, and the room completely finished for habitation), and kept burning for the same length of time. The effect of this was nearly the same with that of the be fore-mentioned and contemporary fire. In the seat of the fire, which was kept up

very strong by additional fuel, the flooring-boards were charred considerably. The plastering of the room gave way; the skirting-board being burnt, the quarters of the ashlering were exposed and damaged; but there was no reason to con sider that the fire would have spread had it been permitted to continue of itself. It should be observed, that in the case of these two experiments, the ceilings immediately under were not laid.

On the same day an experiment was made on the staircase, which was secured with plaster following the steps and risers, and the stairs were finished for use. The string underneath was not laid. A fierce fire was lighted at ten minutes to four o'clock, and kept up till twenty minutes past four o'clock; this fire covered the whole of the first flight up to the garret. Upon extinguishing the fire, it appeared that the risers and treads were considerably charred in the seat of the fire; but there was no reason to suppose that the fire would have spread to any material extent had it not been put out. The plaster remained uninjured.

October 4, 1792.-An experiment was made in the back-room, which was secured with plaster, and finished. A fierce fire was made on the floor, and against the partition which separates this from the adjoining room, and kept up for the space of one hour and three quarters, during which time fresh fuel was continually added. The ceiling underneath was not laid. At the expiration of half an hour no damage appeared; but at the end of the hour and three quarters the fire made its way through the floor, and consumed part of the joists immediately under it, three of the quarters were much charred, the plastering of the partition gave way, and, the quarters behind being exposed, the fire was seen extending itself up them. In this experiment, however, as in the others, it did not appear probable that the fire, if left to itself, would have spread so far as to be of any consequence.

December 26, 1792.-An excellent and convincing experiment was made in the one-pair back-room. The room was completely finished for habitation, the ceiling of the room underneath was finished, which had not been the case in any former experiment, and which, as it admits air to the underside of the fire, was conceived a disadvantage. The partition