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Again, let us suppose that the engine and train had run a certain distance upon a level, so as to obtain a maximum speed, then if with this velocity they begin to ascend a plane of the above inclination, and if the steam could be brought up and maintained at such a pressure, that the pull exerted on the ascent should be to that on the level, as a + b: a, it would evidently follow that the initial velocity would be permanent during the whole

2S+ Vh

3 h

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Consequently (V+v)

Let us now inquire how far the engine and train will move up the ascent with a variable and decreasing velocity, or to the point where it becomes uniform?

Let a distance; then Sa will be the space gone over with the uniform

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12S+Vh

ascent; but it is practically known that velocity v; consequently ÷ (25+

this is not the case: for it is now a wellestablished fact, that an engine cannot exert the same pull at high velocities as it could do at lower velocities; or, as Mr. Robert Stephenson says, "at high velocities the steam does not act so efficiently upon the pistons as at lower velocities." This being granted, it follows that although the steam is brought up to the same pressure in beginning the ascent (with the maximum vélocity), as that which would be required to move the load up the ascent from a state of rest, the velocity in the first case will gradually decrease until it becomes uniform ; and this last acquired permanent velocity will be equal to the full speed obtained when starting from a state of rest.

In both cases the power exerted by the engine is supposed to be the same. This being premised, let S be the length of the ascent in miles, V the initial velocity in miles per hour, and the acquired permanent velocity, then (V+v) will be the average variable velocity per mile an hour, from the beginning of the ascent to the place where the velocity becomes uniform, and § (§ (V +v) +v)

V+39

4

will be the average velocity

4 S.

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+(§ − a) ÷ ( 1 8 = V

3 h

3 h

h) =h; from

2 S + V h

which equation we find x = 6

Suppose an experiment had been made upon a plane rising 1 in 260 feet, length 6 miles, initial velocity 30 miles per hour, and the time in moving up the plane 16 minutes, or 4th part of an hour; then v = (24 −84) 49 miles per hour, and (V+v) = (30 +19)=24 miles, average variable 2S+ V h

velocity per hour, and x =

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6

19

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appears that the average variable velocity is 24 miles an hour; that the effect produced from the initial velocity ceases at the end of 33 miles, and that a perinanent velocity of 19 miles per hour, then takes effect and continues to the top of the summit, and that when the engine and train start from a state of rest, the

greatest velocity they can obtain will be 19 miles per hour.

If a few accurate experiments of this kind were made upon planes of different

TINNING LEAD PIPES.

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SAFETY OF LEAD PIPES PROTECTED BY
TIN.
(Extract of a letter from Mr. G. Chilton, dated
New-York, June 23, 1834.)

Dear Sir,-Observing, in a late number, a notice of Ewbank's patent tinned lead pipes, and having had many applications for information concerning the danger attending the use of metal pipes for conveying water, beer, cider, &c., 1 have been induced to subject the pipes of Ewbank to a few trials, for the purpose of ascertaining whether, from the occasional contact of acids, any deleterious solution of lead would attend their ordinary use. It is well known, that the common beer pump, with a leaden pipe, has frequently given to the liquor a dangerous impregnation, especially after remaining stagnant for a time, and the beer in a sour state. The substitution of block tin would remove the apprehension of danger, but its greater price offers a strong temptation to the use of lead. It appears to me that the lead tube lined with tin will answer the ends of cheapness, safety, and durability. I would therefore invite your attention to the following experiments, which, if you think them of any importance to the public, you may insert in your Journal. Experiments. - Various portions of lead tube, coated, some with pure tin, and others with different alloys of tin and lead, were bent into the form of a semi-circle, and filled with vinegar of different degrees of strength. After standing, some a month, and others six weeks, with occasional disturbance, the

* I observe that this poorest of mathematicians, but most dogmatic and arrogant of all living prigs, has, after being beaten to his utter confusion and disgrace, in the controversy of his own provoking in the Mechanics' Magazine, started a Journal of his own, in order that he may have all his own way, and be no more troubled with such inconvenient antagonists as truth, honesty, and common.. sense. I cordially wish him in his new character and career all the success he deserves; and beg, at the same time, with equal cordiality, to congratulate the readers of the Mech. Mag, on a capital riddance.-I, M.

15

clear solutions were "tested, first with sulphate of soda, and afterwards with bihydro-sulphuret of ammonia. The application of the first of these tests, namely sul. soda, produced no alteration in any of the solutions, from which it must be inferred that they contained no lead.

The application of the second test pro. duced, as was anticipated, a brown precipitate of sulphuret of tin. In the same manner, two fresh pieces of tube were filled with a strong solution of com mon salt, which remained in contact for some time. The solutions when assayed with the same tests, showed that nothing but a little tin was dissolved.

It appears that in all these cases, which I regard as galvanic effects, the tin was the most oxidable metal, although, when not under the influence of polar arrange ment and in the open air, lead appears to oxidiate sooner than tin. It is scarcely necessary to remind you that results similar to these were obtained thirty years ago by the celebrated Professor Proust, at Madrid, who undertook for the Spanish Government an extensive series of experiments on the different alloys of lead and tin, with the express view of determining whether the popular prejudices against the coating of copper which is the common practice, was ill or vessels with an alloy of tin and lead, well founded. Nothing can be more satisfactory than the conclusions he drew from his labours, namely, that as, in all his numerous experiments, neither lead nor copper were dissolved, there is little reason to fear the solution of lead from

the tinning of our kitchen utensils. I may just mention here, that I am in the habit of cleaning out my soda fountain every spring with dilute muriatic acid, which uniformly dissolves the oxide of tin without touching the copper, which I am persuaded will remain as securely as the sheathing copper in Sir Humphry Davy's great experiment, and for the same reason. American Journal of Science and Arts.

TUNNEL UNDER THE OHIO.

A writer in the Cincinnati Journal recommends the construction of a railroad under the Ohio river, opposite that city. The following is an outline of the plan :

The railway is to consist of two semiellipses, one above and the other under

16

TUNNEL UNDER THE OHIO.

neath. The height of the upper arch to be 10 feet, and the lower 3 feet, and 24 feet in width inside, making the ellipse 13 feet high and 24 feet wide in the clear. The arch to be composed of cut stone masonry 2 feet thick. This arch is to be buried in the ground just sufficient to protect it from the action of the river. A floor composed of timbers laid lengthwise, on the bottom of the arch, and covered with planks, forms the carriageways and side-walks. The carriageways to be each 8 feet wide, and the side-walks each 4 feet wide. The sidewalks are a little raised above the carriage-ways. The stones composing the arch are to be cut so as to form segments of the ellipses, and laid in hydraulic cement, and made as near water-tight as practicable. Notwithstanding all the care that may be taken in the construction, yet with a pressure, in time of high water, of 4,375lbs. upon each square foot of the arch, the water will percolate through in such quantities as to require an engine to keep the road dry. It will of course be necessary to light the inte rior when opened for travel.

Between high and low water marks, there is a difference at this place of about 63 feet, and allowing the top of the arch to be 7 feet below low water in the bed of the river, and placing the bottom of the arch at each end, at high-water mark, will make the total descent 83 feet. It is thought that 1 foot ascent in 12 feet horizontal distance is the greatest inclination the road will admit; consequently, the length of the inclined arch, from high-water mark to the bed of the river, will be about 1,000 feet; and allowing also that the bed of the river at low water is about 1,000 feet wide, will make the total length of the road 3,000 feet.

The only difficult point in executing the work will be in excavating the earth and rock below low water. It is quite practicable, however, in a dry season, at comparatively smail expense, to enclose a space with a frame of timber and plank, made water-tight by placing bags of earth around the outside, and pump out the water with an engine placed upon a flat boat, until theexcavation is completed and the arch formed within the space enclosed. Then by moving the same coffer-dam its length farther along, another space can be enclosed, and the work completed in the same manner,

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Total cost of 10 feet of the roadway....565 20 Which being multiplied by 300, for the length, will give 169,860 dollars for the total cost of the arch and flooring. If to the above we add the probable cost of pumping the water and excavating the earth and rock for the roadway, and of covering the arch over again 3 feet deep, it will make the total expense not less than 210,000 dollars. To which should be added 20,000 dollars for superintendence and expenses of the affairs of the company, &c. There can be no doubt that the stock in such an undertaking will yield a handsome profit.

It will be observed that a roadway, constructed upon the above plan, leaves the river entirely unobstructed; that the arch is completely out of the reach of injury from the river; that it is permanent, solid, and will last for ever; and that it involves but a trifling expense to keep it in order for constant use.

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Mechanics' Magazine,

MUSEUM, REGISTER, JOURNAL, AND GAZETTE.

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18

ROOKE'S IMPROVEMENTS IN THE JACQUARD LOOM.

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[We extract the following description of an important addition lately made to the Jacquard loom, from the last Part of the Transactions of the Society of Arts, and are glad (though not surprised) to observe, from the Preface of the Committee of Correspondence and Papers, that the author is of the class of " practical mechanics and weavers of Spitalfields." It is by far the most valuable improvement in silk machinery which has been made for several years past.EQ, M. M.]

Every one knows that in the common loom for plain weaving, the threads of the warp, that is, the longitudinal ones, are arranged alternately into two equal sets; that by the raising of one set an angle is formed between the two, and that the shoot, or cross-thread, is introduced into this angle by a throw of the shuttle; that the set of warp-threads which was first raised is then depressed, and the other set raised, forming a fresh angle, into which the shoot is introduced by a second throw of the shuttle. Thus, by raising each set of warp threads alternately, and throwing the shuttle from right to left, and returning it from left to right, a web is produced of perfectly similar texture in every part. if a number greater or less than half of the warp-threads be raised at once, it is evident that this will produce a variation in the appearance of that part of the web. Such a variation regularly repeated is a pattern or figure and all patterns or figures dependent on the weaving are produced in this way.

But

In the loom for figured silks every thread of the warp is passed through an eye in a vertical cord, to the bottom of which a leaden weight is attached, in order to keep it straight, and to bring the warp thread down again by overcoming the friction; and, therefore, by raising any one of these vertical cords, the warp-thread belonging to it is also raised. By tying together the cords of all those warp. threads that require to be raised at the same time, a single movement will lift the whole of them, and form an angle, or shed, into which the shoot is to be laid by a throw of the shuttle, as already described. For complicated patterns, the number of ties or groups into which the warp-threads are arranged is so great, that much difficulty was experienced in attaching them to any kind of apparatus capable of being worked by treadles actuated by the feet of the weaver.

M. Jacquard, a weaver of Lyons, invented a highly ingenious machine for this purpose, which, from the inventor, goes by the name of the Jacquard loom. He attached a wire,

Each of the

hooked at the end, to every set or group of cords, and arranged them vertically over a triangular bar, capable of being raised by the action of a treadle, and called the lifting bar, because, when in the act of being raised, it carries up with it all those cords or ties the hooks of which catch on the bar. But this, in the natural position of the hooked wires, would be the case with all of them; it therefore became necessary to devise some means of temporarily pushing back the hooks of all those cords that were not to be raised, in order that the others, being lifted, should form the shed of the warp. This is effected in the following manner: hooked wires passes through an eye in the middle of a straight piece of wire, and all these latter wires are arranged horizontally on a frame with the ends projecting a little beyond one side of the frame; the other end abuts against a spring, which yields to any gentle pressure made on the projecting end, and returns it to its place again when that pressure is removed. It is evident, therefore, that if simultaneous pressure is made on the ends of some of the horizontal wires, they will recede, and carry back with them the hooked wires that pass through their eyes, so as to prevent these latter from catching on the lifting-bar when raised by the treadle.

In front of the projecting ends of the horizontal wires is hung a four-sided wooden prism, having as many holes bored in each side as there are projecting wires: this prism has a swinging motion, and turns a quarter round at each oscillation. Now, if this were the whole of the apparatus, it is plain that the prism could produce no effect on the horizontal wires, for the ends of them would be received at each swing of the prism into the corresponding holes of the prism, and thus all pressure on their ends would be avoided. But if we cover each face of the prism, as it swings successively against the horizontal wires, with a piece of pasteboard, called a pattern-card, pierced with holes, corresponding to those of the prism, opposite to some only of the horizontal wires, it is evident that these will remain in their places, and all the other horizontal wires will be pushed back, thus withdrawing the hooked wires with which they are connected from the action of the lifting-bar, which, when raised. will carry up with it only those cords the hooks of which have not been pushed back; or, in other words, those the horizontal wires of which were opposite to the holes in the pattern-card, A throw of the shuttle is made after every oscillation of the prism: as many pattern-cards, therefore, are required as there are throws of the shuttle from the beginning to the repetition of the pattern, including the plain part which lies between such repetition, and also between the different

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