is rather below than above the ordinary rate of difference.

"It was purposely left to the engineers to take their choice of any of the machines, as they found them in the ordinary course of working, no notice having been given to the men, nor any preparation made. As it happened, the stones in hand came from one of the most indifferent strata of the quarry, and the results shown came proportionately below the usual average.

"Had it been thought desirable to show off the machine to the greatest advantage, it might easily have been done, and without the slightest deception, very different results might have been brought out. Thus, on account of their great weight, large stones such as landings, grave-stones, &c., are previously squared in the quarry; when laid on the level, therefore, they fill accurately all the space the machine traverses.

Suppose such a stone, 12 feet long by 6 broad, and 8 inches thick, and that it were required (an ordinary case) to be reduced to 7 inches in thickness. I am quite safe in saying, that the machine will do this in forty minutes, leaving the surface so smooth, that 9d. in hand-labour would bring the 72 feet to a perfect polish.

"Estimating as above the cost of working four machines for sixty hours at 91. 10s. 6d., forty minutes of one machine would amount to 6d., but say an hour or 9d. as the cost of hewing 72 feet by the machine, that is about one-eighth of a penny per foot.

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"To bring the stone to the same state by hand, the mason would require to go over it with four operations. He would, to speak technically, 1st, dab it over rough with a puncheon;' 2d, broach it close with a puncheon;' 3d, 'scabble it with a chisel;' 4th, angle drove it for polishing.' In this state, in consequence of the bruising operation of his chisel on the face being greater than that by the machine, it would cost twice as much to polish it. The cost of the above four operations, at the lowest estimate, would be 24d. per foot. Thus the cost of hewing by hand and by machinery, would, in this case, be as 20 to 1.

"In estimating the outlay by the machine, ample allowance is made for the handling of the stones, the chief expense in the wages of the extra people attached to the mill, while nothing is charged for the assistance the mason would undoubtedly require in setting up and moving his stone. If this were taken into account, it would go far to double the comparative difference."

After receiving the above information, the Society thought the matter one of so much public importance, that they appointed a Special Committee of their number to repair to Leysmill, to " ex

amine the machine in operation," and report the result of their personal examination. The Committee consisted of the following gentlemen:

Lord Panmure.

Mr. Carnegie, of Craigo.
Mr. Hawkins, of Dunnichen.
Mr. Millar, of Ballumbie.
Mr. Proctor, of Halkeston.

This Committee paid a visit to the quarries, accordingly, on the 29th of June last, and the following is their Report to the Society :

"With reference to the statements contained in a letter of date the 10th day of June current, from Mr. Lindsay Carnegie to the Secretary of your Society, your Committee are convinced that these statements are fully borne out, and beg to submit the result of their own observations-the following facts:

"There were put upon the bed of the machine at the same time, three pavementstones in a rough state and of unequal thick nesses; the first of which contained 12 superficial feet, requiring to be reduced two inches in thickness; the second, containing 16 superficial feet, requiring to be reduced three quarters of an inch; and the third, containing 18 superficial feet, and requiring to be reduced one inch and a quarter; the whole of which stone, amounting in all to 47 superficial feet, were reduced and polished in thirty minutes, including in this the time occupied in shifting the irons.

"Your Committee beg further to state, that with a view of comparing the working of the machine and hand labour, they interrogated Mr. Donald Mackay, master mason and builder, in Arbroath, who stated that to have accomplished the same work in the ordinary way by the hand, would have occupied a good mason five days and a half, at a cost of 15s. 9d., according to the present rate of wages in this part of the country; whereas, according to calculations submitted by Mr. Lindsay Carnegie, and which your Committee have every reason to believe correct, the expense would amount to about 1s. 7d.

"In addition to the trial above noticed, your Committee saw stones, of the hardest quality, from different quarries in the country, dressed by the machine with a corresponding advantage; and your Committee cannot close this report without expressing their conviction of the great advantages to be derived from the extended operation of Mr. Hunter's machine, as being the means of preparing for the market as pavement, a quality of stone, which, without its assistance, could never be turned to account, as also the great saving to be obtained by its

application to this hewing and dressing of all sorts of free stone.

"Your Committee beg leave also to report, that by the same steam-power they saw in operation the same principle applied as an experiment to a turning machine, from which they are satisfied that it may be applied with economy and advantage to the turning of stone vases, and other ornamental work."

"Leysmill, June 29, 1835."

The concluding passage of the preceding Report recalls to mind that we have yet one of the most valuable properties of this machine to notice—namely, that besides facing and dressing blocks of stone, it can be made (with the help of a lathe coupled to it) to turn, bore, and hollow them as well. Columns, ballisters, vases, drilled chairs and sleepers for railways, &c., may all, by this machine, be produced with a degree of accuracy, despatch, and economy, wholly unattainable by hand labour. We men

tioned in our notice of the last Meeting of the Institute of British Architects (vol. xxiii., p. 349), one remarkable proof of this, which Mr. Carnegie presented to that Society, namely, a handsome vase turned out of the solid block, in the course of a single day's work, twenty inches high, and eighteen across the mouth. But this is nothing, we find, to what Mr. Hunter is making preparations to accomplish in the course of next winter's leisure. He talks with great confidence of being able to produce vases four feet high !—exact copies of our finest antiques, in all but the ornamental tracery, which must still remain to be done by hand. Of the ease with which holes might be drilled in stones by such combined machinery, the following extract from a letter, which we have seen from an eye-witness, furnishes equally striking evidence. He is describing a first trial in boring made by Mr. Hunter. stone," he says, was old quarried and of the hardest yolk, and 54 inches thick, the bore 1 inch diameter, and the time in going through the stone was exactly 27 minutes; it ran through it like wood."

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"The

The Arbroath stone on which Mr. Hunter's machines have been hitherto chiefly employed, has been long in great request for foot-pavements, market-places, kitchen-floors, &c.; and now that it can be produced by means of machinery in any quantities, will probably become still more and more so. It possesses this great

advantage over the Yorkshire flag, that it resists the damp much better and dries more quickly; while it is, at the same time, equally cheap. In this point of view it has but one rival, the Caithness flag, to which however it is, in uniformity and homogeneousness of texture, vastly superior. In Scotland this species of stone, painted and varnished, is now getting into extensive use as a substitute for marble; it is a great deal more durable than Scagliola, and not half so expensive.

WILLIAMS'S SELF-INFLATING LIFE-BUOY.

It is well known to all who have witnessed shipwrecks, that instances sometimes occur where it is very difficult, if not impossible, for a boat to come close to those in distress; such as a reef of rocks, sand-banks, or a heavy surf breaking over the wreck. It has been sug. gested, that in such instances a communication might be effected by a boat anchoring as near as possible to windward, and veering away a light buoy and line to be carried to leeward by the wind to those in distress, who might, by these means, be hauled through the surf into the boat. An objection of some little weight was started as to the difficulty of stowing away in a life-boat (already filled up with air-cases,) a buoy of sufficient size and buoyancy to be strongly acted on by the wind. A self-inflating lifebuoy made of India-rubber has, therefore, been contrived, which, when out of use, admits of stowage into a small compass, and is speedily available without complexity or difficulty on the part of the crew. The inventor is the Rev. Dr. Williams, of Llanfair Ynghornwy, Anglesey, Secretary to the Anglesey Branch of the Royal National Institution, for the Preservation of Life from Shipwreck. Dr. W. directs that" when the buoy is wanted you are to unscrew the vent, pass the becket or loop at the lower end over your foot or thawl-pin, or any thing handy, and extend the buoy by means of the upper becket, taking care that the vent is fairly open; as soon as it is extended to the utmost, screw down the vent, when the buoy becomes ready for use. The whole operation is easily effected in ten seconds." Dr. W. further recommends, that a light Manilla should be used, as having more tendency to float, and being less kinky than hemp when wet,"

Sir,-Many nautical men having complained of the want of publicity of my patent windlass in some of the distant ports, whilst it is being so generally adopted and appreciated in those where it is known, I will feel obliged by your inserting the accompanying description of its construction, action, and advantages,

THOMAS SOWERBY.
Patent Windlass Works, near Shadwell
Dock Basin, London, Oct. 7, 1835.

Fig. 1 is a section of the windlass body and side-view of the iron cylinder, which is firmly wedged thereon, with part of the flange broken off, to show the position of the patent iron pall and riding-chock when riding at anchor. The pall and riding-chock are each made on the segment of a circle, with teeth on their concave sides corresponding with the teeth on the cylinder.

Fig. 2 is a front view of the same, and part of the windlass body; also of the wedge bolt, which is inserted above the pall to lock it when riding. The pallplate is bolted to the pall-bit, and has a bolt passing through its flanges, by which the pall is guided when working. The shoe or deck plate is also bolted to the pall-bit, and, through a timber, to the deck, and has a bolt through its flanges for guiding the riding-chock, also a slit parallel with the deck for guiding the bolt passing through the wood or ridingchock wedge..

Action and Advantages of the Patent Pall.

Before getting the anchor, the ridingchock is ungeared from the cylinder by driving out the wood-wedge by a short crow or lever, and the lock-bolt is withdrawn from above the pall. When the windlass is hove round, the pall rises and falls perpendicularly in the succession of the teeth on the cylinder, thus palling at once every tooth on nearly a quarter of its circumference. It thus offers a more solid resistance than a series of palls, such as have been commonly used, and which are shown at fig. 3, and its action against the pall-bit is much nearer to the deck. It cannot possibly trip or be upset, as, from

its wedge-like form, it becomes but more firmly fixed as the strain increases. Neither is it injured by screwing or otherwise straining the deck-timbers, but fits alike, however the windlass is raised or depressed; on which account it has proved particularly valuable to ships carrying wool, hemp, and other screwed cargoes, from many of which the common palls had been taken out. If the cable ride, or a handspike foul, the windlass may be immediately run backward by lifting the pall. It is always in full pall, and to meet a sea, or for riding or veering the cable, it may be instantly converted into an efficient riding-chock by inserting the lock-bolt, which effectually prevents the windlass from being moved either way.

Of the Riding. Chock.

For riding, the pall being locked, the riding-chock is raised by a lever, and the wood-wedge driven in until the chock is firmly geared with the teeth on the cylinder. By this simple and quick operation, the windlass becomes a complete fixture with the pall-bit and deck, which cannot be moved whilst they remain fast, as it is secured alike in every direction, being literally embedded in iron. It is so readily applied, that the windlass may chocked or unchocked instantaneously, and at any time, as the pall and chock fit alike to every part of the cylinder. It does not strain the windlass from the pallbits, like the common wood riding-chocks, but supports it to the pall. It occupies less space, and allows the windlass to be made shorter, if required.

be

The whole apparatus can be applied to any ship's windlass, and at a less expense than the common palls and wood ridingchocks. It is more easily fitted, and not liable to get out of repair; and is peculiarly adapted to the use of chain-cables. It has already been adopted on board of vessels from 30 to 960 tons register, including East and West Indiamen, English and foreign traders, steam-packets, cutters, &c.; and the reports of the many intelligent and experienced commanders who have it in use, and who have put it to the most severe and complete trial, are at once gratifying and conclusive as to the many great and important advantages it possesses. In short, all agree in allowing it to combine compactness, cheapness, and security.

PERILOUS BALLOON ASCENT.

Mr. Clayton, the western aeronaut, narrowly escaped a sudden and violent end, during a balloon ascension which he made on the 21st August at Lexington, Ky. He had risen to an elevation of about two miles, when the perilous occurrence alluded to took place. We subjoin his own account of it.-American Railroad Journal.

"At twenty-three minutes after five, when at an altitude of two miles, I discovered that the gas had completely filled the balloon, and that the neck had become entangled between the cords by which I was suspended, preventing the surplus gas from escaping, and confining the valve-cord so that I could not open the valve.

"I immediately busied myself in liberating the valve-cord, and while in the act of doing this, the neck and cord were snatched with violence from me, the upper portion of the balloon burst with a tremendous noise, and I and the whole fabric fell two or three hundred feet, with the velocity of a stone. The rapid descent was then a little checked; and now the most critical moment of my life was at hand-a moment that required calmness, presence of mind and activity, for an awful scene presented itself. The lower part

of the balloon, by the violent resistance of the atmosphere, in descending, had been pressed against the surface of the net-work, and formed into a parachute, of about twenty-five feet in diameter; but through the centre of this imperfect parachute I could behold the naked valve, the small meshes of the net, and a great portion of the silk on each side, which formed the resisting surface, hung in ribbons, dashing from side to side, and producing a noise like that of shattered sails of a ship in a tempest. This hurricane noise was not produced by the rapid descent alone, but by the violent oscillatory and rotary motion of the parachute. At one moment I was almost in a horizontal line with the parachute, and then I was dashed through the air to a level on the opposite side; thus describing an arc of nearly a semi-circle, the radius of which was about fifty feet; and at the same time I and my car were whirling with sickening velocity. While in this situation I succeeded in dashing overboard all my bags of ballast, which weighed about 80lbs.

"In four minutes 1 descended about a mile, and reached a region of dense clouds. At this time I untied the upper end of my cable and held it in my hands, threw over my anchor and allowed it to swing at the full length of the rope (150 feet); it was thrown at every vibration far above the level of my

car.

"On passing beneath the cloud, I saw the town of Athens a little to the south-west of me. In five minutes more I reached the ground with a pretty severe shock, but sustaining no injury worth mentioning. The whole balloon or parachute, was instantly flat on the ground, a mass of ribbons. A few dark faces (negroes) appeared at a short distance from me, with outstretched hands-screaming-frightened to death at the huge machine that came whirling over their heads, and still more frightened when they saw me spring out of it."

MR. HERAPATH'S FORMULA FOR VELOCITIES ON INCLINED PLANES.

Sir, I am afraid Mr. Herapath's bed for some time to come will not be a bed of ; but he has made it for himself, roses and must, therefore, try to repose himself upon it in the best way he can. Although he can scatter censure in every direction without either measure or mercy, yet he is himself so very thin-skinned as to take offence at any expression that can in the slightest degree be supposed to call in question his own infallibility. In his rather intemperate reply to Mr. James Combe, C. E., he describes the red

shanked and breekless clan (to which I myself am not ashamed to own I belong), as coming from the North in shoals, like herrings, with tartan petticoats, &c. Again, in No. 2 of his series, p. 167, vol. xxiii., in speaking of the opinions of men of science, he says, "there are some with whom a good fee will always procure a good opinion, and even prove that the steeper and more difficult is the easier line to be worked." I think we may, without uncharitableness, conclude, that there is just as much ground for ascribing to any section of our men of science a greater regard for fees than facts, as for the alleged want of breeches' pockets to hold them. I do not believe there is a single man of science, whose opinion is worth having, who would, for the sake of a few pounds, give an opinion which he knew, in his own mind, to be erroneous. Such random imputations and such coarse language, are but ill calculated to promote the interests of truth and free inquiry.

Mr. Herapath, in addition to his great mathematical attainments must, I conceive, have some intimacy with the occult science; for I find, in No. 629, he states that the value of h in his newly-discovered

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scends, cannot safely be taken above 6 feet per mile, or one in 880. Now, in my last article, No. 634, which was writ ten a considerable time before his, I requested him to give the greatest value of h, so that we might know when his formula presented a true or a false result. But be this as it may, we shall assume h=6 feet. Will this value of h, according to his formula, produce a true result? Let us see.

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