ing letter to be all perfectly correct, they fall a very, very great way short of establishing the practicability of the pneumatic railway scheme. The tubes on which Mr. Hague operates, are, as Mr. Pinkus states, close tubes," close at both ends; they are very small tubes, too, (Mr. Pinkus's notion that the smallness is a disadvantage, is but another proof of his ignorance); and no greater exhaustion is required to be effected at any one time, than is equivalent to the quantity of atmospheric air admitted at each downward stroke of the piston or pistons, kept in action. Once exhausted, they are (subject to the exception just stated) always exhausted. To infer from so limited an exhausting action as this, that it would be equally practicable to exhaust pipes of nine square feet in area, and five miles long (Mr. Pinkus's proportions!) and that not once, nor twice, nor thrice, a day, but as many times a day as there were carriages sent along the line, is just as reasonable as it would be to infer from the force of Aldgate pump, the possibility of pumping up the great Atlantic.

The analogy between the transmission of gas and the transmission of heavily laden carriages through tubes (or a-top of them) is, if possible, still more fanciful and remote. It would be a waste of words, however, to reason about it; there is manifestly no analogy whatever.

We said, and we still maintain, that while the hempen ropes by which the stationary engines on railways are now worked will do any work (within the limits of their strength) that is assigned to them, "Mr. Pinkus's aereal substitute could not be worked at all." What is the utmost in the way of rarefaction which the stationary steam-engines on Mr. Pinkus's plan could accomplish? Perhaps a third, or possibly half, of a vacuum; any thing approaching to an entire vacuum (such is the extreme expansibility of air) is admitted on all hands to be out of the question. Dr. Lardner says, that a vacuum of one fifteenth, to a fall of two miles in a barometric gauge, would suffice for all working purposes. But be the degree of vacuum required in the railway tube or tunnel what it may-a half, a third, or a fifteenth-it is certain that it will require a complete vacuum in the steam cylinder to produce it. In any event, and under all circumstances, a complete vacuum

must be employed to produce a very partial one. Now, exactly in proportion to the degree of vacuum produced in the railway tubes, must its working capabili ties be. If, as our intelligent correspondent, Mr. Berry, has pointed out, (see last No., p. 89.) the exhaustion is carried no further than Dr. Lardner proposes, that is, a fifteenth, then will the carriage be propelled no further than a fifteenth of the entire length of the tube; or, if the exhaustion is pushed as high as a third, or a half, there will still be two-thirds, or a half, of the distance left untraversed. Instead of the railway carriages accomplishing five miles at a time, as, according to Mr. Pinkus's calculations, they ought to do, they would be found sticking fast at one, two, and three. You may multiply the number of stationary engines as much as you please, the result would still be the same; the impulsive or efficient power obtained would always be something less than the steam power employed to produce it. Nothing, in fact, short of exhausting the tunnel completely, every time a load was passed over it, could suffice to realize Mr. Pinkus's scheme, and that-within economical limits, at least is a physical impossibility.

We laughed at the peculiar claim set up by Mr. Pinkus to the "power of surmounting acclivities;" but we gather from some communications which have been addressed to us on this point, that we had not pointed out with sufficient clearness in what its absurdity consists. Let us revert to it, then, for a moment, before we take our leave of the subject. "The first striking feature in this, the pneumatic system of railway," says Mr. Pinkus, in his Prospectus," is the power it possesses of overcoming acclivities insurmountable by the locomotive steamengine, and without diminution of speed." Now, the utmost pressure that can be exerted under the pneumatic system behind the impelling diaphragm, is the pressure of something less than one atmo sphere, while locomotive steam-engines may be worked at many atmospheres; and it is also certain that, let the pressure be what it may, gravity must of necessity operate to the diminution of speed. Is it not, then, extremely absurd in Mr. Pinkus to pretend to be able to do more with a fraction of one atmosphere than others can do with two, three, or half a dozen atmospheres?-Highly ridiculous in him to

imagine that a carriage, propelled by any power whatever, can act independently of gravity-go as fast up hill as on a level→→→ with a load as without one? Not only exceedingly ignorant, but exceedingly quackish?

Were even Mr. Pinkus's scheme as correct in point of principle as it is erroneous, it must be rejected, on the score of economy alone. For, prodigious as his pretensions on this head are, there is not a particle of truth or feasibility in them. We are spared, however, the trouble of entering into this branch of the subject, by the letter, from a respectable correspondent, which we subjoin; we leave it in good hands.

Mr. Pinkus complains of the tendency of our observations to "injure" him in his "property." We are always sorry when our duty, as public journalists, obliges us to pursue a course that may be attended with individual injury; but, in the present case, our sorrow is greatly lessened by reflection on the extent of pecuniary mischief to others, which our exposure of the folly of Mr. Pinkus's scheme may possibly be the means of preventing. Mr. Pinkus boasts that 16 many of the wisest, noblest, and worthiest in England have already recognised" it to be "useful and valuable;" but, notwithstanding his amazing good luck in this respect, it appears from the daily advertisements in the newspapers of the "National Pneumatic Association," that the necessity still remains of appealing to the commoner portions of the community for those "sinews of war," without which the project must, in spite of the flattering opinion entertained of it by so many wise, and noble, and worthy personages, fall to the ground. The total sum proposed to be raised is 200,000l.. in 10,000 shares of 201. each; and of this sum it is probable that by far the larger portion has still to be subscribed. If, therefore, we can but be the humble instruments of stopping this nonsensical affair where it is, we shall make two or three thousand yet unhooked (though perhaps eyeing and nibbling) holders of spare cash, our everlasting debtors. Mr. Henry Pinkus will be a loser, but the community at large exceeding gainers.

As to the personal civilities which Mr. Pinkus has heaped upon us, in return for the pains we have taken to set his

merits in a fair light before the public, we must leave such of them as have not been honoured with special notice in the preceding remarks, to speak for themselves. We did not labour for his praise, and are not at all touched by his reproaches. That we should be abused by Mr. Pinkus and his partisans, is no more than we expected; pretenders and speculators, when baffled and exposed, are always abusive.

THE PNEUMATIC RAILWAY FINANCIALLY CONSIDERED.

Sir,-Will you allow me, through the medium of your excellent Magazine, to suggest to the public (at least to those who are not already aware of it), the total fallacy of the financial representations upon which the "National Pneumatic Railway Association" have taken their stand.

Your scientific objections to the scheme, Mr. Editor, would at once be sufficient, to a nechanical man, to confute their assertions; but the public generally re quire to be convinced by comparisons of expense, that there is no advantage to be obtained from it. This task is, in the present instance, by no means a difficult one; were it even to prove that, instead of being a benefit, it will be productive of total ruin to all those concerned in it

excepting always the professional gentlemen, promoters of the plan, &c. &c.

The Prospectus of the Association goes such lengths as broadly to assert "that, by the improved system, a line of road may be constructed for, at most, twothirds, and in some cases for one-half, the expense incurred by the common system, &c.

The Professional Director may take his choice of a wilful imposition upon the public; or, what in his case is scarcely less pardonable, a most gross error in calculation. Tredgold has stated, in his Essay on Railroads (p. 141), that the average expense per mile of a double line of railway, as taken from railroads constructed, is, as nearly as possible, 4,000l. Now, two-thirds of this is about 2,700, a sum per mile, which, by the showing of the Professional Director, is to cover all their expenses. Well, their pipes are to be 40 inches diameter, and for the requisite strength, say 14 thickwhich will not be too thick, as there is a valvular opening through its whole length

-the weight of this pipe per mile, for a single line only, will amount to 1.160 tons !! This, at 101. per ton = 11,6007. per mile; or 23,2001. per mile for a double line, in the cost of the bare material.

It is not necessary to trouble you any further with a detailed estimate; but I am prepared to prove, that the contingent expenses upon a double line (a few of the principal of which are, boring pipes, labour in joints, flanges, &c.; digging out foundations, setting in conerete, labour in fixing, cost of ground, stationary engine and houses, railroad carriages, &c. &c.), will not amount to less than 35,000l. per mile; and as the capital of the Company is stated to be only 200,000, their job will only extend to about 34 miles! A national undertaking, truly, and one that will, without doubt, in their own language, “induce the proprietors of all the ordinary railroads and canals in this country to avail themselves of its advantages, and thus all become tributary to the Associ ation," &c. &c.

For the sake of Doctors Faraday and Lardner, it is really to be hoped that the scheme will be dropped without the question being raised of its practicabi lity, as there is great reason to believe that they have been, in some manner, drawn into the affair without a perfect knowledge of the use to which their names were to be applied. I am, Sir, &c.

46, Lower Belgrave-place, May 14, 1835.

W. M. P.

CLARK'S BLOWERS.

Sir, I have just had one of Clark's Blowers described in the Mech. Mag., and though I don't find that they will make a good fire in "one minute," yet they perform so satisfactorily, that I think there never ought to be another pair of bellows made. The fly was twelve inches in diameter, and before the spout was fixed on, I found that the air was not drawn off in a tangent, but had a very sensible curve; so I made the spout as near the curve as possible, as it is very obvious that there should be no more obstruction than is unavoidable, either from friction or from making the spout small, as it is quantity, and not intensity, that is wanted. I also find it advantageous to have a bent spout to take off and on,

as the front is not always the best place to blow a fire, and sometimes a few turns under the grate will do more than three times the number in the front. It will work with either two, four, or six flies; but I have not ascertained which is the most advantageous number, or whether it would not be advisable to incline the flies from the line of motion.

Might not an instrument of this sort be used as a substitute for the air-pump? Suppose one to be made strong, and to work a collar of leathers, and to have the feed-pipe to fix into a well thirty feet deep. If it were thus put in rapid motion by means of a small pulley, and a very large fly wheel from high, would the water rise? This is an important question, as there are so many stills and boilers now made on the vacuum principle, for if it would only raise the water fifteen feet high, a large still might have half the air driven out of it.

Captain Henry Kater.-The scientific world has to deplore the loss of Captain Henry Kater, whose various labours in mathematical and physical re. searches, for nearly half a century, have greatly enlarged the hounds of experimental science. He was born at Bristol, April 16, 1777; and in 1794 obtained a commission in the 12th regt. of Foot, then stationed in India. During the following year he was engaged in the trigonometrical survey of India under Colonel Lambton, and contributed greatly to the success of that stupendous undertaking. About the same time he constructed a peculiarly sensible hygrometer, and published a description of it in the Asiatic Researches. His unremitted study during seven years in a hot climate greatly injured his constitution, and was the cause of the ill state of health under which he suffered to the close of his life. He went on half-pay in 1814, from which period his life was wholly devoted to science. His trigonometrical operations, his experiments for determining the length of a pendelum beating seconds, and his labours for constructing standards of weights and measures, are well known; they combined patient industry, minute observation, and mechanical skill, with high powers of reasoning. Most of the learned societies in Great Britain and on the Continent, testified their sense of the value of Captain Kater's services, by enrolling him an:ongst their members. The Emperor of Russia employed him to construct standards for the weights and measures of his dominions, and was so pleased with the execution of them, that he presented him with the order of St. Anne and a diamond snuff-box. The even tenor of Capt. Kater's life was rarely interrupted. The loss of his daugh ter, who fel a victim to her ardour for science in 1827, was the severest affliction by which he was visited. She died in her seventeenth year, after having displayed mathematical powers of a high order, and a love of science that even increasing physical weakness could not destroy. Mest of Capt Kater's publications appeared in the Philosophical Transactions, to which he was a very constant contributor.-Athenæum.

The Birmingham Town-Hall.-In the last number of the Architectural Magazine there is a very spirited and manly letter from Mr. Hansom, the architect (now of Hinckley), pointing out two or three rather serious mistakes in the account which was given, in that journal, of the authorship of the design of the Birmingham Town-hall, and transferred from it to our pages. "It happens, fortunately for me," says Mr. Hansom, "that, in the declaration I am about to make, there needs scarcely a single reservation; and when I state that the design of the Town-hall is as much mine as St. Paul's Cathedral was that of Sir Christopher Wren, I state solemnly and sacredly the truth. It is quite true that the site of the building, and the height, length, and breadth of the hall were prescribed; and, what I lament, the tasteless and absurd galleries which permanently disfigure it. It is also true, that, at the suggestion of a gentleman connected with the musical arrangements, an alteration was made in the interior decoration or finish of the walls, by substituting Corinthian pilasters and cornices, for an adaptation of the Íonic antæ, which I had designed; but, with these exceptions, I can take up the plans, elevations, sections, and working drawings, and declare that, line for line, there is not one that can be pointed out as the suggestion, or that was based upon the idea or imagination of any living bei g besides myself." Further: "Many of your readers will recollect that the competition for the Fishmongers'-hall did not take place till nearly a twelvemonth after that for the Town-hall at Birmingham; they will be astonished, therefore, as I was, with the sentence in the article from which I quote, which states that the design for the latter building was one jointly produced by Messrs. Hansom and Welch two years before, and which was intended for the Fishmongers'-hall, London! The designs that were made for the Fishmongers'-hall (but not adopted), purporting to be these of Messrs. Hansom and Welch, were made in the month of December, 1832, by my own hand, from my own sketches, and were the result of my own studies, equally with those of the Birmingham Town hall." Mr. Hansom ought to be better known than he is. The designer of so noble a structure as the Birmingham Town hall has surely a higher destiny in reserve for him, than any which a small and remote town like Hinckley can offer. The whole country suffers, when men of Mr. Hansom's stamp are suffered to waste their energies on any other than works of the first national importance.

Metropolis Spring - Water Company. We believe, with C. B. G., that this is a very absurd and delusive project; but, if we are not misinformed, it is already in articulo mortis. We insert, in this week's Number, a most convincing letter on the subject, from an eminent "Manufacturer ;" and may also refer to Mr. Matthews's just published work, " Hydraulia" (to which we shall pay our respects soon), for some very forcible illustrations of the folly of the scheme.

One of the last Numbers of the Penny Cyclopædia contains an article on the "Bear," in which there is one extract in Latin, and several, of some length, in French, without an attempt at translation! Do the worthy members of the Useful Knowledge Society imagine that these languages are now so universally diffused among the working classes for whom they stated The Penny Cyclopædia" to be intended-that they are the same to them as their own mother tongue? If not, why fill the columns of their work with matter unintelligible to the mass of its readers? Strange to relate, they still think it expedient to furnish a translation to quotations in Greek.

Gravesend Railway.-It is understood that the project of a railway from Greenwich to Gravesend is at present at a stand, in consequence of the Princess Sophia, as Ranger of Greenwich Park, having declared herself hostile to the plan for car

rying it in that direction. It is much to be questioned whether the shareholders ought not to be obliged to her Royal Highness for throwing cold water on the scheme, since the probability of profit resulting from its operation, with such a formidable rival as the Thames all the way, seems to be extremely small.

The Brussels and Mechlin Railway was opened on the 6th of May, in the presence of an immense concourse of spectators. At a quarter past twelve o'clock, the King being at the station, near the Boulevards, to witness the ceremony, the departure of the steam-carriage train was announced by a salute of artillery. Immediately three files of ten carriages, each carrying nearly a thousand persons, began to move, drawn by the Flèche, the Stephenson, and the Elephant. The passage from Brussels to Mechlin occupied fifty-three minutes. On their return the Elephant took in tow all the thirty carriages that had been drawn by the three locomotives, and would probably have reached Brussels in half an hour, had it not been obliged to stop at Vilvorde for a fresh supply of water. the evening the Minister of the Interior gave a public dinner to 200 of the principal persons, natives and foreigners, who were present at the cere mony.-Brussels paper.

In

Mr. Stephenson has been appointed a Knight of the Order of Leopold.—Ibid.

New Description of Cabriolet.-A vehicle of this description, hung upon a new principle, has just been brought out at Paris, and is now all the rage there. Its advantages over the old one are greater lightness, easiness, and cheapness. The principal difference is in the mode of suspending the body. In the patent cab the square frame is dispensed with, and the substituted one may be best described by likening it to a hay-fork, supposing the horse to work within the prongs, and the body to be built upon springs upon the handle, which is laid across the axletree. By the balancing of the body upon a single perch, the movements backward, forward, and laterally, are much easier, and the whole is rendered lighter. It of course requires good screwing at the point where all the springs radiate upon the beam of the scale, to maintain the body in its proper position, but as constructed, it is said to answer well. The principle of resting bodies on a point in the middle, is not new in the construction of four-wheel carriages.-Morning Herald.

Communications received from Enort-Rev. R. Carey Mr. Maynard-Mr. Baddeley-M. N.-A Young Chemist-Bergein-A Radio et Pulvere.

The Supplement to our last Volume, containing Titles, Index, &c., with a Portrait. on Steel, of Samuel Clegg, Esq., C. E., is now published, Price 6d.; also the Volume complete, in boards, Price 88. 6d.

Our Publisher will give One Shilling and Sixpence for copies of the Supplement to Vol. IX.

Patents taken out with economy and despatch; Specifications prepared or revised; Caveats entered; and generally every Branch of Patent Business, promptly transacted. Drawings of Machinery also executed by skilful assistants, on the shortest notice.

LONDON: Published by J. CUNNINGHAM, at the Mechanics' Magazine Office, No. 6, Peterborough court, between 135 and 136, Fleet-street. Agent for the American Edition, Mr. O. RICH, 12, Red Lion-square. Sold by G. G. BENNIS, 55, Rue Neuve, Saint Augustin, Paris. CUNNINGHAM and SALMON, Printers, Fleet-street.