Ystalyfera cold-blast iron, from furnace

Breaking weight. . lbs.. 618

-equal to 57 9-10th per cent.

Difference

..lbs.. 496

lbs.. 122

Deflection.

lbs.. 1.988

1.632

......lbs.. •356 Force to resist impact. .lbs.. 1297 821

.lbs.. 476 Breaking weight. lbs.. 674 496

..lbs.. 178

--equal to 18 8-tenth per cent.

lbs. 1-916

1-612

lbs. 304

-equal to 79 per cent.

lbs. 1235

690

.lbs. 545

lbs. 1235 734

-equal to 68 2-10th per cent.

From these, and the former comparative experiments, it is abundantly evident that the pig-iron, now making with cold-blast and anthracite, at the Ystalyfera Iron Works, greatly exceeds, in strength and deflective powers, and capacity to resist impact, any iron at this time manufactured in the United Kingdom. It now only remains for me to mention a property peculiar to the iron, which was noticed at the time I made the trial experiments at Yniscedwyn, four years ago, but which has been more fully developed in those recently made at Ystalyfera. The property referred to is one of great springi

..lbs. 501

ness, or elasticity, which communicates a tendency to the bar, in deflecting and breaking, to resume its rectangular form. Bars that had obtained a permanent set of 2-10ths, when afterwards broken, presented but a slight deviation from a right line; and in no case did the acquired curvature exceed onefourth of a tenth. It was also remarked, that most of the fractures, in breaking, presented a regularity of grain throughout, resembling the structure of unhardened steel. DAVID MUSHET.

Coleford, Nov. 18.

Sir, It was only this day I learnt from a friend that Mr. Elijah Galloway, C.E., in a work on "the Archimedean screw and other submarine propellers,"-(we shall some day, I presume, have a numismatic writer publishing an account, in imperial quarto, of the sixpence, or the silver penny)-has been pleased to say, the shades of Mendez Pinto, and of the Lord of Campoli, hovering over and directing his pen-that the screw-propelled "steam-ship," on a certain occasion, ran with the Swiftsure, and ran round her.

The truth is as follows. On the 6th of June, the Swiftsure quitted her moorings at Greenwich, and went down the river, for the purpose of adjusting her new ropes. As she passed Blackwall, the said "steam-ship," called, I believe, the Novelty, (why not "Wimshurst's Folly ?") then lying there with her steam up, started for the purpose, as was afterwards seen, of running with her. Upon the Swiftsure's reaching Erith, she turned, and met the Novelty worming her way by Half-way Reach. The latter turned about, and from thence, as far as Blackwall Reach, endeavoured to overhaul her, till then, unconscious antagonist. "Hue magno cursu contenderunt," and at Blackwall

Reach the Novelty came alongside the Swiftsure for a few seconds, but there falling far astern, for the fifth or sixth time, she tacked about the distance from the Reach to Greenwich, being too little for another shoot. The Swiftsure, during this last run, was compelled to slacken once, for full ten minutes, that the tightening-screws of her ropes might be put on, and no more than 32 of her 40 horses' power, (low pressure,) owing to the newness of the ropes, could, on an average, be employed.

The tide against the vessels, on their return, was taken at two miles; but the "steam-ship" being fully rigged, it was considered the strong wind in favour balanced her account with it. The singular irregularity of her speed-evidencing that many times her feed-pumps were shut off, for the purpose of keeping her steam in her boiler was remarked, as was the extreme blue of her exhaust steam, denoting the enormous pressure upon it. Her mode of steaming resembled much the progress of the Gyrinus (water flea).

What the speed of the Novelty may be, (7 miles in her advertisement for sale,) and what the speed of the Swiftsure, we are not

here called upon to inquire. The relative speeds of the Archimedean screw and of Mr. Blaxland's propeller-the target fired atare at this very time being tried by Govern

ment.

Such are the facts-" Perspecta et explorata sunt, quæ scribo."

Yours, &c.,

C.

P.S.-It may not be quite uninteresting to your readers to be informed that the Little Jane, whose extraordinary performances you have recorded, has been now some time in the service. She is the pinnace to the Salamander, from off which frigate she is destined to land the British Ambassador, the Right Hon. Henry Ellis, at Rio.

November 28, 1842.

DOMESTIC FIRES AND KING'S STOVE GRATE.

Sir,-Your correspondent, "T. H. B.," (with whose style I somehow fancy myself acquainted, although I do not remember his signature,) seems (p. 494) to have been so very anxious to dispute the few remarks upon combustion which I took the liberty of sending you, and to which you were kind enough to afford a place in your columns, that he almost forgot to ascertain what the remarks themselves were, and to what they applied: how far he apprehended their object appears from his assertion, that I complain that, from the escape of unconsumed gas in common grates, heat is lost;" my remarks having had regard altogether to the prevention of smoke, without at all referring to the loss of heat, or any means of saving it. I may now add, that I consider the latter an insignificant desideratum, when compared with the former; in reference, of course, to the consumption of fuel in a large city.

The importance of this subject is well contended for in the extract from Mr. Curtis's work on "The Preservation of Health," which appeared in the same Number of your Magazine as your correspondent's letter: and undoubtedly, the recommended general adoption of Mr. Williams's" argand furnace" in all London manufactories would greatly abate the smoke nuisance, but I fear that we can scarcely expect thus to remove it entirely; for it must be allowed that the enormous quantity of smoke generated in the innumerable domestic hearths throughout "the great Metropolis," would be of itself sufficient to constitute a very injurious degree of impurity in the atmosphere, as well as a very visible fog. This consideration it was that suggested the remarks in question.

The difference which we sometimes per

ceive between the combustion at the front of the grate and at the back, I referred to want of air, and with reason I am inclined to think, as the supply of air in the latter situation is far inferior to that in the former, and the heat in both must be nearly alike.

Your correspondent, however, contends (apparently, for he does not express himself very clearly) that this is owing to want of heat, and I can assure him I have no wish to disturb his opinion, or commence a dispute on such a trivial subject, it being, besides, one upon which it were impossible to arrive at anything like demonstration; of course he would greatly respect a mathematical proof.

My recommendation, that the back of the grate should be assimilated somewhat to the front, so as to admit air, is construed by your correspondent into a detailed suggestion on my part, that it should be "perforated with holes;" this plan, though rather in a crude state, I am, however, willing to adopt as far preferable to the corrugated back, whose virtues are lauded by your correspondent. I cannot, however, subscribe to the supposition that it is useless, (with regard to its heat-giving power) to have the back of the fire as brilliant as the front, still less to the original idea, that "at the same expense, more heat will be obtained by keeping a large fire, bright in front, but black behind;" both which rest on the erroneous notion, that the heat thrown out by a fire depends upon the heat in the front merely, and not upon the actual quantity of heat in the whole fire, the latter being the real source from which to estimate the heating effect; for we find that the heat thrown out by a furnace through its door, depends as much upon the size and heat of the furnace, as upon the size of the door. Moreover, the heat transmitted to the wall cannot be considered as lost, any more than the power transmitted by any kind of machinery, for it all comes into play again, being diffused through the wall, and in this manner expended in warming the rooms at each side.

Your correspondent's plan for a stovegrate will be considered, I should expect, too unseemly an excrescence in a room to be generally adopted; although, perhaps, it may be a medium between the stove method of warming a room, by communication and heating the air in it, and the more peculiarly English method, radiation; which, permitting us while comfortably warm to enjoy a comparatively cold and fresh atmosphere, seems too firmly fixed in use in this country to be easily changed,-an Englishman at once perceiving an unpleasant closeness in a room warmed by a stove, (without much draught), even though it be kept at

Sir,-Perhaps you will permit me to add a postscript to my letter already forwarded, as I have just seen the account of Mr. King's stove in your last Number (No. 1009).

The introduction of this subject seems to have produced a combustion among the stove-loving part of your readers. I hope that it may not, like the imperfect one deprecated, end in smoke.

I can easily believe that Mr. King's stove carries out my view, more than J. H. B.'s does; but it does not come up to my beau ideal of an anti-smoke grate, and differs very considerably from one I was about planning a short time ago, but which I have not had leisure to finish, as the details require much consideration, as well as experimental examination of the subject. This, however, is a case in which nearly the same end may possibly be arrived at by apparently differing means. And, besides, it is very little matter whether my suggestions are carried out or not in Mr. King's stove, if it is a good consumer. I am sure his conductor would be an excellent addition to most grates, and probably go far to cure a smoking chimney, although it might, perhaps, sometimes be the means of originating a puff. I am, Sir,

Your obedient servant,
R. W. T.

DOUBLE REVOLUTION STEAM-ENGINESBUNNETT'S CONCENTRIC ENGINE.

Sir,-Your correspondent, Mr. Thomas Rolls, who sends you a sketch of a "Double Revolution High Pressure Steam-engine," (described at page 514,) states that he considers it "perfectly new," and to him I have no doubt it is so.

I think it right, however, to state that the "double revolution" part of the affair, forms one of the "Improvements in Steam-engines," for which letters patent were granted to "Joseph Bunnett, of Deptford, Engineer," in June 1838! Mr. Rolls must be content therefore, to forego the "obvious advantages" of his invention, though what he supposes these advantages to be, is not stated. His vibratory engine consists of an arrangement that has been invented, re-invented, and patented some score of times, but has never yet been found to realize in practice any very "obvious advantages."

Bunnett's Concentric Steam-engine, to which the "Double Revolution" movement

was applied, has been found in use to realize all the advantages ever claimed for the semi-rotative class, without entailing any of their numerous defects. A description of this engine was published in your 31st volume, page 210, and an engine of this description has been in daily use for the last four years at the patentee's works at Dept. ford, where it may be seen in operation by any person who feels an interest in the matter.

The "Cambrian Oscillating Engine," described at the commencement of the present volume, in its action bears a striking resemblance to Bunnett's concentric engine, but a comparison of the two will show that there is a wide and important difference between them,

I am, Sir,

Yours respectfully,

WM. BADDELEY.

29, Alfred-street, Islington. December 7, 1842.

RAILWAY REFORM.

Some more killing and breaking of bones, and, as the customary sequel, a little more reform. It would almost seem as if the Companies habitually resisted to the killing point all improvement, in order that they may have the adoption of some universally called for alteration of system, to set off against each fatal accident as it occurs-to reconcile the public, as it were, to the disaster of the moment, by the reflection that it has brought about a change which will make railway travelling all the safer for the future.

The accident to which our attention is at present called, is one on the Birmingham line, by which one person has been killed, and three others seriously wounded. It was caused by the overturn of the engine, through the breaking of the front axle, and that engine a FOUR-wheeled one, with inside bearings-the very sort of carriage which the Birmingham Company, its officers, and its engine builders, have of late been striving so hard to persuade the public is incapable of being overset from any such causeso much so, that it could run almost as well with an axle sawn through, as entire.

Mr. Parker, the foreman of Messrs. Bury, Curtis and Kennedy, the engine builders to the Company, in his evidence at the coro