CURTIS'S CHIMNEY-HOOD AND ASH-PAN

FOR LOCOMOTIVE-ENGINES.

Sir, I send you a drawing and description of my chimney-hood and ashpan for locomotive-engines, as used on the London and Greenwich Railway, and shall feel obliged by your insertion of the same in your valuable pages.

The Hood.-The chimney of the engine is covered with a dome, which projects the steam and heated air escaping into the atmosphere upon a surface of water contained in the receiver or outer vessel, so that any sparks or other matter ejected from the chimney must necessarily be received in the water, and consequently extinguished. The condensation of the steam, together with the priming of the boiler, supply sufficient water to keep the bottom of the receiver always covered; and for the purpose of carrying off any excess of water, a small tube is fixed to the bottom of the receiver, and this pipe stands up about 1 of an inch, so that a plate of water of 14 inch deep is always ensured. The pipe enters the chimney and forms an elbow, which elbow also is always full of water, so that no fire can possibly pass through it. It is my intention eventually to form the dome double, and to pump up the cold water, which will be thus heated by the waste steam, and then to pump this heated water into the boiler, thus converting the apparatus into a feed head. I find a space all round of about four inches sufficient for the passage of the steam, &c. I have put this invention to the most severe tests I could devise, but could never force a spark from the chimney. The engine runs freer and faster than with the gauge, the draught is unimpaired, the apparatus is cheap and simple, and absolutely safe.

Description of Engravings.

Fig. 1 is a section, and fig. 2 an elevation of the hood: a, chimney; b, receiver, containing water; c, dome or hood; d, bent tube; the curved arrows show the path of the steam, air, &c.

The ash-pan is a box of sheet-iron suspended under the fire, and water-tight, so that the water filtering through the fire-box a is received into it. The pan is about eight inches deep, and the sides rise above the fire-box about three inches all round, so that the dust in the act of falling is not blown away during the progress of the engine, or by the wind, and

being received into water is, of course, immediately extinguished, while the water is evaporised; and the vapour not only prevents the coke from clinkering on the bars, but materially assists the combustion. The box is open all round and hehind about eight inches, thus providing abundant area for the passage of the air to the fire. It is suspended behind by a joint to the framing, and before by a chain which coils round the axle of the hand-wheel f, so that when the engineer wishes to discharge the ashes, or rake the fire-bars, he merely lets go the wheel, when the pan falls down, describing the curve shown by the dotted line.

Description of Engravings.

Fig. 3 is a section, and fig. 4 an elevation of ash-pan and part of the boiler: a, fire-box; b, boiler; c, fire-bars; d, ash-pan, containing water; e, hinge of ditto; f, hand-wheel; g, chain by which the pan is suspended. The curved arrows indicate the path of the air.

Your most obedient servant,
W. S. CURTIS.

Deptford, August 6, 1836.

MR. SYMINGTON'S REPLY TO MR. HOWARD.

Sir, Mr. Howard's communication contained in your last Number betrays such evident marks of being got up in haste, that I am certain by this time even Mr. Howard himself will scarcely deem it worthy of serious refutation.

I shall, therefore, content myself with referring such parties as may take an interest in the question to the drawings accompanying Mr. Howard's specification and to those in my circulars, where it will be found the difference between the two inventions is any thing but “immaterial."

In one part of his letter Mr. Howard says, "I may add, that the process (his, I suppose) auswers completely;" in reference to which I have merely to observe, that not being aware how far Mr. Howard's notions of completeness extend, I will not, for a moment, think of contradicting him, but briefly remind him, that the more simple any useful invention is, so much the nearer is it to perfection. Bearing this fact in mind, I fearlessly leave it to Mr. Howard's own judgment, whether he will venture to say that his invention is possessed of the greater simplicity.

? One thing more, and I leave Mr. Howard calmly to reflect, whether it was fair to deal in assertions which he can neither substantiate, nor has taken due pains to ascertain to be wellfounded although such assertions might produce an unfavourable impression regarding the conduct of an individual to whom he was a stranger. He has ventured to assert, that I saw his process in operation at the King and Queen Iron-Works, Rotherhithe, upwards of two years ago; but this assertion is as erroneous as that he has anticipated me in my plan of condensation, for I can and do most positively affirm, that during the whole course of my life I never saw his principle, or method, or process, either at work or at rest; neither did I ever set foot within the walls of the King and Queen Iron-Works, Rotherhithe.

So

much for hasty conjecture! Unless Mr. Howard can disprove my positive affirmation, surely he cannot but regret having so phrased his assertion, as that it might tend to create suspicions of my being unprincipled enough to visit him for the purpose of surreptitiously depriving him of his plan of condensation.

Trusting you will oblige me by giving this insertion,

I have the bonour to remain, Sir, Your most obedient humble servant, WILLIAM SYMINGTON. 1. King William-street, London Bridge, Aug. 10, 1836.

THE ELECTRICAL THEORY OF THE

UNIVERSE.

Sir, I am somewhat inclined to think that your correspondent, Ursa Major, and your humbler servant, Kinclaven, Care old acquaintances; however, be that as it may. It appeared from his first article on the Electrical Theory of the Universe, that he was a waverer between the Newtonian and Mackintoshian theory; but, from his last, he appears to be about three-fourths charged with electrical fluid, and no doubt one lecture more will make him brim-full. forms me that he is no stranger to the demonstrations that have been given on the general law of the tides by all the great mathematicians (La Place included) who have lived since the days of Neweton; and he very modestly requires me to translate their demonstrations into the language of common sense." That is,

He in

in plain English, he (Ursa Major) having neglected to cultivate those talents with which Nature has gifted him, would wish me to show him some "royal road" to physical astronomy that would shorten his journey.*

Mr. Mackintosh informs us (No. 645) that his theory is in accordance with Kepler's laws. And again, in No. 655, he states that our earth must at one time have been attended by at least five moons. We shall see how this agrees with one of Kepler's laws, namely, that the squares of the periodic times are as the cubes of the mean distances from the sun.

Let t and T be the periodic times of two planets, d and D their mean distances, and V their angular velocities. Then, by Kepler's law, t: T:: d3 : D3; also, from the laws of central forces, t D2 V2'

and T2

d2 D2 hence : :: d3:D3, v2 V2

DV2.

d2 v 2 from which it follows, that do2 Again, Mr. Mackintosh informs us, that the paths of all the planets are becoming nearer and nearer into circular orbits, and

ultimately they will all be whirled into the body of the sun. Supposing this to be the case with the planet whose present mean distance from the sun we have designated by the symbol d; then when that event takes place, d=0.. dv2 = o, but when d ceases to exist so must v.. v2o; also since dv DV2, therefore DV2 o, hence one of the factors D or V2, or both, must be o; if Do, then the angular velocity V ceases .'. V2 0. Again, when Vo, it follows, either from the laws of gravitation or the elec trical theory, that if D is not = o, it will quickly be so, for the planet then would be only acted upon by a centripetal force; and it would be contrary to either theory to suppose that the second planet (when Va), like Mahomet's coffin, could be suspended in mid-heaven. It therefore follows, that if Mr. Mackintosh's new theory is in accordance with the law of Kepler-when one planet is destroyed, all the rest will almost imme diately share the same fate the same reasoning may be applied to the case of the five supposed moons, but as we are

Ursa Major, I presume, has not read Professor Airy's little work entitled "Gravitation," which was noticed in the Mechanics' Magazine more than a year ago. I would recommend him to read it, as it is well adapted for those who are not deeply read in mathematical science.

340

MR. DICKSON'S REPLY TO THE CORNISH ENGINEERS.

Sir, In the observations (No. 675) on my letter to you (in No. 669), the writer begins with the verb to be, or the difference between the word was and is. So little is this difference, that this was and is is not the word that I alluded to, for it was and is the application of the definite article the to the noun nursery (in place of the indefinite a), which intimated that Cornwall was and is the only nursery for steam-engines. I assure you, sir, I had and have no wish to offend any one, either in word or deed; besides, I am not the only person who have taken notice of the glaring improbabilities set forth with respect to Cornish steam-engine work. The writer complains of my not addressing myself to him as taking upon himself to be the champion of the Cornish engineers; but this I must decline, because my remarks appertain generally to so many persons whose names have been attached to the accounts of different performances for several years past.

Mr. Enys has not given any other reason for the increase of duty, but repeated that it was and is from the improved pit-work and their complete system of clothing, together with the use of high steam used expansively, that they have been enabled to do so much with a bushel of coal. Now all these they have had, now have, and shali have in future; nevertheless, I repeat my protest with all that accompanies it in my letter, dated May 25, 1836.

The writer says, that Mr. Watt's amount of duty was obtained by the same mode of calculation as that used to obtain the others, adding the following words:66 admiting that both are subject to the well-known error of a result higher than the actual delivery of water." Now, sir, after this I hope you will perceive that the incorrectness and carelessness which the writer has attributed to others, belong entirely to himself and party, and that

they only are in difficulties, and although "they regard with the utmost apathy the opinions or assertions of engineers nof other parts of the kingdom," perhaps the public will not do so, because controversy has often been the means of arriving nearer to the truth, and this was and is the reason why I wish them to begin their calculations again, taking truth or facts as the foundation, to depart from the unit, and in place of a hundred millions raised one foot high, let us have a mil❤ lion of pounds weight raised a hundred feet high, &c. The writer also states, that at certain mines from a comparison of two different years there was a great difference in the quantity of coal paid for, and that "the water delivered was assumed to be the same in both years." Now this is rather too bad-even to dis} card calculation, as well as their admitted "well-known errors," which have as sisted them in showing their hundred and odd millions. Whatever erroneous cal culations cannot do, assumptions of course will easily accomplish. Every engine, worker knows that his engine (if in good order) will only consume coal in propor tion to the work done; and I presume it will not be denied that most of the water raised from mines first descends from the surface of the earth in spite of the precautions used to prevent it; consequently a rainy season often makes a great difference. In some districts there are mines to be found where the water is drawn from about three-fourths of the depth, while in the lower quarter scarcely any water is found. Suppose, for instance, any of the clever men, since Mr. Watt, had been able to enforce the payment of a portion of the savings that has been effected, would the proprietors have quietly submitted all this time to the ac counts being all on one side ? Some that I have spoken to, say no; and farther, that we should never have heard of their ten-times-ten millions, and so forth, if there had been any opposite interest to contend with. The writer speaks of the difficulty of measuring water from dif. ferent levels; but from the average surface of the water in the sump, or place from which the pump draws it to the point of delivery, I believe is what ought to be taken, and they cannot all be such cramped holes in Cornwall, that a couple of cisterns cannot be put or formed in the strata, each to hold a few minutes or hours' delivery of the water from the