a height or level, equal to the height of the pipe itself, or twenty feet. Now, it is well known that the theoretic velocity of water, flowing out of an aperture, is equal to that of a heavy body falling from the height of the head of water, which is found, very nearly, by multiplying the square root of that height in feet by 8, for the number of feet described in a second. Thus, a head of 1 foot gives 8, a head of 9 feet 24, and a head of 20 feet 354 feet per second. This is the theoretical velocity; and from what is equally well known respecting the vena contracta, or the contraction which all streams undergo when passing through orifices, we must, in order to obtain the actual velocity, multiply the square root of the height, in feet, by 5 instead of 8. It is equally well known, from the experiments of Venturi, Bryan Donkin, and others, that when water flows through a compound cone, as exhibited in the wood-cut, the quantity discharged, and, consequently, its velocity, is even greater than that due to the theoretic velocity. But as the twenty-feet pipe, under consideration, terminates in an elbow, just before its junction with the double cone, I am quite willing, in order to prevent dispute, to consider the velocity of the water through the double cone as that due to the contraction of the stream. Hence ✓ 20 x 5 224 feet per second, instead of 35 feet, as above stated.

=

I have already had occasion to remark, that the diameter of the suction pipe, nine feet long, which passes from the lower part of the double cone into the pipe, ggg g, is th of an inch; hence, the diameter of that pipe being

th of an inch, and the velocity of the water flowing over it, at its junction with the cone, twenty-two feet per second, the time occupied, or taken up, by any given particle flowing over its diameter, is th part of a secondequal, decimally, to 00227 of a second.

"Now, by the laws of gravitation, the space through which a body will fall in a given time, in feet, is as the square of the time, in seconds, multiplied by 16. Hence, 002272 × 16

x 12 in. = 0001, very nearly, or about a thousandth part of an inch. Hence, by the laws of gravitation, and consider ing, at the same time, the expansion of

inch

the outward cone, from to 1 diameter, and that, too, in a length of 5th inches, there is not time, in the passage of the water over the orifice of theth inch pipe, for any portion of it to fall into that pipe; hence, as the water flows over the orifice of that pipe with rapidity, it, by its friction or adhesion, or the lateral communication of motion in fluids, withdraws from it some portion of the air, and, subsequently, of the water, so as to produce a partial vacuum. The weight of the atmosphere, in the downcast and upcast pipes of the patented apparatus, then comes into play, and forces the water in those pipes continuously from the pipe, gggg, up theth inch pipe, and then through the larger cone, until the surface of the water in the bend pipe, b to c, gets below the level of the nine feet pipe, and, consequently, is below the bottom of the bend. Thus, Mr. Editor, without valves, clacks, pumps, or any thing that can get out of order, is this important object effected.

June 21, 1841.

I am, Sir, yours, &c., HENRY ADCOCK, Civil Engineer.

from this circumstance, made numerous railway trips in order to detect the cause, and to find a remedy for the evil. -ED. M. M.]

WHITELAW AND STIRRATT'S PATENT
WATER MILL.

(From the Paisley Advertiser, June 26.) Since the invention, a few years ago, of this admirable method of using water power, we have had frequent occasions of directing public attention to its merits. On Wednesday last, one of them was set a-going in Stirlingshire, and as it is of much greater power, being 95 horse, than any heretofore erected, we shall give a few particulars relating to it, to show that the fears entertained by many of its efficiency on a large scale, have proved groundless. The works at which the mill we now allude to is erected, are those of the Culcreuch Spinning Company, Stirlingshire. The building is 6 stories high, nearly 200 feet long, and 38 feet wide; and it contains above 20,000 mule spindles, several hundred throstle spindles, with the other machinery necessary in such a work. The fall which supplies it with water is 37 feet, and the quantity of water is 1,800 feet per minute. Heretofore two overshot waterwheels have been employed; one old one of 32 feet diameter, by 12 feet wide, taking 1,200 feet of water per minute, the other nearly a new one, 33 feet in diameter, and 5 feet wide, requiring 600 feet per minute. The united power of the two wheels was supposed about 60 horse, and they were barely sufficient to drive the machinery. In place of these two wheels one of Whitelaw and Stirratt's Patent Water Mills has been substituted, and, as we have mentioned, it was set in motion on Wednesday night. From some accidental flaw in one of the castings, which could not be foreseen, the point of one of the arms was, by the centrifugal force, thrown off. This, of course, did not admit of immediate repair; but as the work-people had been summoned to their labour for next day, it was necessary to provide a temporary expedient. This was done by removing the broken piece at the joint, and screwing a stout piece of wood over the orifice. Of course this was reducing the power of the mill one half, but it was thought better to drive as much of the machinery as possible, and employ part of the hands, rather than let the whole remain idle. On Thursday morning the water was admitted to the mill, thus deprived of the use of one of its two arms, when, to the delight of all, it drove freely the whole of the machinery. The mills, noticed by us from time to time heretofore, were generally

of a small size, varying from 5 to 18 horse power, except one of 59 erected in Greenock. When describing the latter, we noticed that its powers were ascertained by friction apparatus, but as the nature of this is little known, except to scientific men, it would be a more satisfactory test to see the mill do the real work for which it is erected; and this test was fully supplied at Culcreuch. Trials have now been made of these mills from 1 up to 95 horse power, and their great superiority over the ordinary waterwheels, has, within that range, been fully tested. Their great superiority in point of compactness over the ordinary wheel is so apparent, that we need not dwell on that point. With respect to economy, the advantages are as great as they are in other respects. The expense of erecting a waterwheel at the Culcreuch works, of sufficient magnitude to make the whole power of the fall available, would, with its arc, have cost at least 2000l.,while the expense of the patent mill, including the pipes for conveying the water to it, will not exceed £600. The additional power possessed by these mills seems to many a matter of mystery. We do not profess to describe the cause fully, but there is one circumstance which in itself affords a pretty full explanation. The water-wheels at Culcreuch made only about four revolutions per minute, consequently the interven. tion of a great quantity of gearing was necessary to bring up the speed. This, of course, consumed much of the effective power, but this drawback is got quit of by the speed of the patent mill itself, which makes sixty revolutions a minute, while it is so accurately balanced, as to diminish friction to the smallest possible extent, leaving the whole power of the water to be advantageously employed in driving the machinery. A farther improvement has been made on the mill since we last noticed it, but this we have not left ourselves room to describe. We shall let it suffice to state that the object of it is to overcome the disadvantages which mills are subjected to by back-water in the millrace. There can, we think, be little doubt that as water-wheels wear out, these mills will be substituted, till they become general, and to this they are, from their simplicity, compactness, power, and economy, fully entitled. The demands for them are already so great, that the patentees have been unable to answer them, and to prevent disappointment they have resolved to grant, in the three kingdoms, licences to the extent of twentyfive. Some of these have already been taken out in this neighbourhood by the principal engineers in that line. Of course the public will now have various sources of supply.

CASE OF JAMES MAXWELL, THE STEAMBOAT PILOT.

It is hoped that no apology will be required for bringing before the public the following case of extreme distress, connected as it is with circumstances which must be interesting to every generous and humane individual under whose notice this may come :

In the 171st number of Chambers' Edinburgh Journal there is a narrative, detailing an instance of one of the most miraculous preservations of human life, from destruction on board ship, that has almost ever occurred. It is under the title of "A Hero in Humble Life," and exhibits the self-denial and bravery of one James Maxwell, (under the fictitious name of Cochrane,) a pilot, who, in the year 1827, was the individual means of saving the lives, to the number of betwixt seventy and eighty, of the passengers and crew of the Clydesdale Steam-packet. This vessel was destroyed by fire on her voyage betwixt Glasgow and Belfast, and the preservation of those on board of her, by the pilot, is thus abridged from the article in Chambers' Journal alluded to:-"On its being ascertained that the only way to save those on board was to run the vessel ashore, the pilot instantly took the helm, and fixed himself to the spot. The fire, which the exertions of all the men could not keep under, soon raged with ungovernable fury, and, keeping the engine in violent action, the vessel, one of the fleetest that had ever been built, flew through the water with incredible speed. All the passengers were gathered to the bow, the rapid flight of the vessel keeping that part clear of the flames, while it carried the fire, flames, and smoke backward to the quarter-deck, where the pilot stood like a martyr at the stake. Every thing possible was done by the master and crew to keep the place on which he stood deluged with water, but this became every moment more difficult and hopeless, for, in spite of all that could be done, the flames seized the cabin under him, and his feet were literally roasted on the deck. Still he never flinched, for, had he done so, all might have perished. At intervals, the motion of the wind threw aside the intervening mass of flame and smoke for a moment, and then might be heard exclamations of hope and gratitude, as the multitude on the bow got a glimpse of the brave man, standing calm and fixed on his dreadful watch. By this time the vessel was within a stone-cast of the Galloway coast, girded as it is with perpendicular masses of rock, but every corner of which the pilot was acquainted with, and this enabled him to run her into an open space, and alongside a ledge of rock, upon which every person got safe on shore, all unscathed, except the self-devoted one, to whom they owed their lives."

The foregoing particulars have been all ascertained to be true. Poor Maxwell, how

ever, was so injured, and his constitution so shattered, by his exertions and sufferings on that awful occasion, that he has never been the same man since. For several years subsequent to this occurrence, he was employed as a pilot by one of the most respectable Steam Companies on the Clyde, but for a long time he has not been able to do a hand's turn. He is now completely bed-ridden, (in fact, in a dying state,) and labouring under severe rheumatism of the breast and legs, from the effects of the fire. He has a wife and six children, the eldest only fourteen years of age, and all are completely destitute.

As it is supposed that many humane persons would feel pleasure in extending their charity towards this deserving individual, if assured that it would be applied properly, the following gentlemen, who have inquired into, and are conversant with, the circumstances of the case, have formed themselves into a Committee, for the purpose of receiving contributions, and properly applying the same, namely,

Mr. Robert Napier, Engineer, Glasgow. Messrs. Thomson and Macconnell, Steam Packet Agents, Glasgow.

Messrs. William and Robert Chambers, Conductors of the Journal, Edinburgh.

Mr. R. W. Hamilton, General Steam Packet Company's Office, Edinburgh, and,

Mr. George Mills, Shipbuilder, Bowling Bay, Glasgow, Secretary for the Subscription.

The facility afforded to the community by the penny post in forwarding subscriptions to any of the above-named individuals is respectfully suggested; and it is hoped that those who may be only able to afford small sums, will induce others to join them in making up an amount easily remittable. It is likewise hoped that editors of newspapers will give insertion to this notice as an act of charity, if suitable with their arrangements.

REMOVAL OF SUNDERLAND LIGHTHOUSE.

At a late meeting of the commissioners of the river Wear, the taking down of the lighthouse being discussed, as part of the plan of building the new north pier at the mouth of the harbour, Mr. Murray, the engineer, suggested the removal of the lighthouse, in its present entire state, to the eastern extremity of the new pier, a distance of about 420 feet, so as to make it serve the double purpose of a stationary and a tide light. Mr. Murray exhibited a model of the building, and after explaining how he proposed to effect this undertaking, the board decided that he should proceed forthwith to remove it. This light

house was erected about forty years ago, b the late Mr. Pickernell, then engineer to th harbour commissioners. It is wholly composed of stone, its form is octagonal, fifteen feet in breadth across its base, sixty-two feet in height from the surface of the pier to the top of the cornice, where it is nine feet in breadth across, and the top of the dome is sixteen feet above the cornice, making a total height of seventy-eight feet, and its calculated weight is 250 tons. Mr. Murray intends to cut through the masonry near its foundation, and insert whole timbers, one after another, through the building, and extended seven feet beyond it. Above and at right angles to them, another tier of timbers is to be inserted in like manuer, so as to make the cradle or base a square of 29 feet; and this cradle is to be supported upon bearers, with about 250 wheels of 6 inches diameter, intended to traverse on six lines of railway to be laid on the new pier for that purpose. The shaft of the light-house is to be tied together with bands, and its eight sides are to be supported with timber braces from the cradle upwards to the cornice. The cradle is to be drawn and pushed forward by power

ful screws, along the railways above mentioned, on the principle of Morton's patent slip for the repairing of vessels. However surprising the removal of such a building may appear to many, yet in New York, for some years past, large houses have been removed from their original situation to a considerable distance, without sustaining any injury. The immense block of granite, serving as the pedestal of the equestrian statue of Peter the Great, at St. Petersburgh, was conveyed four miles by land, and thirteen by water. Several obelisks have likewise been transported, at different times, from Egypt to Europe; and lately, one was conveyed from Thebes, and erected by the French at Paris. But the fact that the light-house on our north pier is composed of stones of comparatively small dimension, its great height, and small base, make the operation of removing it much more difficult than any thing of the sort ever attempted. We heartily wish the enterprising engineer every success in his bold and novel undertaking, which is to be carried into execution in the course of a few weeks.-Junderland Herald.

My first plan is this: two magnetic bars are laid side by side with their dissimilar poles against each other. Two other bars of the same description are placed at right angles on the middle of the former. This makes four successive rows of magnetic bars, each row possessing a northern and a southern polarity. These bars are inclosed in a wooden wheel, the centre of which, I shall suppose, rests upon a finely-pointed pivot. In order to make this wheel revolve, I take five powerful magnets strongly secured, so as to prevent any motion in them, and of which the five north poles, A, B, C, D, E, (which are alone required,) are placed as shown in fig. 1.

Now it will be seen, that in every position of the wheel containing the smaller magnets, the attraction of the large north poles for the south poles of the small magnets, and repulsion of the large north poles for the north poles of the small magnets will combine, to give to the wheel a rotatory motion.

I am but slightly acquainted with the science of magnetism, (this is perhaps the cause of the delusive idea under which I am now working,) but I think that in case two magnetic bars laid side by side should not exhibit sufficient energy, four horse-shoe magnets, placed as in the annexd drawing, fig. 2, could be used with the same, or perhaps a greater advantage.

April 5, 1841.

mechanism applicable to turn-tables for changing the positions of carriages upon railroads, which improvements are also applicable to castors for furniture and other purposes.-Enrolment Office, June 18, 1841.

These improvements comprise first, the application of anti-friction collars to vertical and horizontal axles; secondly, an improved