has been produced by the absurd statements put forward with an air of science and authority by the public newspapers, has arrived at such a pitch, that the Academy of Sciences has deemed it requisite to notice it, and formally to refute the newspaper statements. It is a singular feature of society in France, and in Paris in particular, and is a theme for the politician and psychologist, that this people -so eminent for physical science, and alas! too, for the absence of religionare so readily and so frequently put into absurd panics about expected or predicted dangers, either in the heavens above or the earth beneath them. Thus, a few years ago, Arago had to reassure them, in a formal essay in the Annuaire, to prove that Encke's comet would not smite the earth, and either burn or drown them; and now the Academy has to step forward to assure them that Paris will not be swallowed up in the immense gulf which the well at Grenelle will, they fear, wash out under the city.

The Daguerreotype.

M. Bisson has found that, by placing in the cup which contains the mercury, (in the Daguerreotype process,) a little alcoholic solution of iodine, the mercury and the iodine evaporate together, and give to the as yet invisible image, when produced, a tint much more agreeable and pleasing for portraits than those at present obtained, which certainly are most cadaverous-looking things.

231

Aver.

Fur

In weekly

naces. blast. make.

162 112

9000

Total ........ 527 350 25531

It will be thus seen, that the number of furnaces in the United Kingdom is 527, of which 350 are in blast, and 177 out of blast, the quantity of pig-iron made, or capable of being made, at the present time, (by the furnaces in blast,) being 1,327,612 tons per annum, from which, however, we may deduct 20 per cent.-leaving 1,062,090 tons as the actual make. On comparing this statement with an abstract of the quantity of pig-iron estimated to have been manufactured in the year 1839, and which is embodied in Mr. David Mushet's work, entitled " Papers on Iron and Steel," we find the average weekly make at that period to have been as follows:

STATE OF THE IRON TRADE.
(From the Mining Journal.)

We are enabled this week to furnish a tabular statement, showing the number of furnaces in and out of blast in the United Kingdom, with the weekly "make," in most instances taken from data on which no question can arise as to the accuracy of the returns, while, in other cases, we have adopted such estimates as appeared to us, from the information derived, to be sufficiently near for the attainment of the object in viewthat of presenting to our readers a complete table, wherein the several iron works of the United Kingdom are classified, and the weekly product, as also the aggregate re

turns.

The following summary will at once exhibit the present position of the iron trade:

Newcastle-on-Tyne

Scotland.....

Forest of Dean

South Wales
North Wales

Total

20 13 650

429 379 24005

Or an annual "make" of 1,248,260, which is called in Mr. Mushet's work 1,248,781 tons. It will be thus seen that, comparing the present make with that of the average of 1839, the number of furnaces in that year was 429, of which 379 were in blast; whereas, in February, 1842, the number had increased to 527, of which only 350 were in work, the majority being at a reduced make of 25 per cent.-the aggregate quantity made weekly being, in 1839, 24,005 tons, and in February, 1842, 25,531 tons-there being an increase, in the past two years, of 98 furnaces, equal to an additional make of 407,680 tons per

quence of the ports being all round the cylinder, and the valve travelling therefore about th part the distance of the common D slide valve. It does away also with a deal of work, such as the Ď valve, valve jacket, packing blocks, &c. The steam may be also, by this means, worked expansively to a greater advantage than at present, as it is necessary to have an additional expansion valve for the present D valve, when it is desired to work steam expansively. I am, &c.

THOMAS MERITON.

Mill Wall, January 27, 1842.

MR. C. W. WILLIAMS'S PATENT FURNACES -MESSRS. DIRCKS AND CO., AND MR. ARMSTRONG.

Sir,-Our attention has been called to a letter from Mr. R. Armstrong in your Journal of the 5th March, in which a slight is attempted to be thrown on us, merely in consequence of our acting as principal agents for the argand furnace of Charles W. Williams, Esq.

We are quite satisfied in our own minds that no unprejudiced party can read the communication alluded to, without being convinced that all sober argument or scientific inquiry is at an end with an individual who can descend to the style of that letter. Such is our impression, and much as we feel disposed to make a few remarks on the unwarranted assertions of Mr. A., we shall refrain from so doing, not only from entertaining this opinion-of itself sufficiently strong-but also for the following, if possible, more cogent reason. We decline entering the lists with Mr. Armstrong, he having within the last fortnight declared, in the strongest language, the most implacable hostility towards Mr. Williams, and a determination to attack him, and whatever emanates from him, by every means in his power. We state this coolly and advisedly, and are prepared to support the assertion.

It is not, therefore, from our being unable to controvert Mr. A.'s statements, but from a wish to keep free from his personal abuse, and a contest in which none but an interested party can feel any concern, that we decline taking further notice of the letter in question.

We are, Sir,

233

VARIATION OF THE NEEDLE-GREENWICH MAGNETIC OBSERVATORY.

The needle is known to have had a westerly variation ever since about 1657. The late Colonel Beaufoy, who made a long series of very skilful and accurate observations on the subject at Bushy Heath, about ten miles N.W. of London, considered that he had ascertained that in March, 1819, this varia. tion had attained its maximum, being then 24° 41′ 42′′ W., and that it had begun then to decrease at an annual rate of 1' 37". A writer in the Quarterly Review makes the retrocession contemporaneous with the great breaking up of the Polar ice in 1816 (three years earlier than the date assigned by Colonel Beaufoy), but not on any sufficient authority. In 1839 a Magnetic Observatory was added to our national Greenwich establishment, and the observations which have been since made there, under the superintendence of the Astronomer Royal, Professor Airy, confirm the general correctness of Colonel Beaufoy's conclusions, though they indicate the annual decrease to be greater than he supposed. The results obtained for the last two years are as follow:

1840 1841....

......

23° 23' 30" W. 23° 17′ 40′′ W.

The Magnetic Observatory at Greenwich is erected on a piece of ground adjoining Flamstead House. The following description of it is given by the author of an interesting article, "On Telluric Magnetism" in the United Service Magazine for March last :"It is entirely built of wood, and completely insulated. The free magnet is a bar of hard steel, 2 feet long, 1 inch broad, and

inch thick, suspended by a skein of silk fibre from two pulleys fitted to a suspension frame about 9 feet above it. Before the magnet there slide two small brass frames, firmly fixed in their places by means of pinching screws. One of these contains, between two plane glasses, a cross of delicate cobwebs; the other holds a lens of 13 inches' focal length, and nearly 2 inches' aperture, which combination serves as a collimator without a tube, and perfects the adjustment."

THE ATMOSPHERIC RAILWAY.

Opinions of Professor Barlow and Col. Sir Frederick Smith, R. E.

A Report has been laid before Parliament, which was made to the Board of Trade on the 15th of February last, by Professor Barlow and Sir Frederick Smith, on the merits of the atmospheric system of railway, invented

and patented by Mr. Clegg, and fully described in our 882nd Number. The opinion of these two highly competent authorities is decidedly favourable to the adoption of the system. They sum up their Report by declaring

"1. That we consider the principle of atmospheric propulsion to be established, and that the economy of working increases with the length and diameter of the tube.

"2. That the expense of the formation of the line in cuttings, embankments, bridges, tunnels, and rails, will be very little less than for equal lengths of a railway to be worked by locomotive engines; but that the total cost of the works will be much greater, owing to the expense of providing and laying the atmospheric tube, and erecting the stationary engines.

"3. That the expense of working a line on this principle, on which trains are frequently passing, will be less than working by locomotive engines, and that the saving thus effected will, in some cases, more than compensate for the additional outlay; but it will be the reverse on lines of unfrequent trains. However, there are many items of expense of which we have no knowledge, and can form no opinion, such as the wear and tear of pistons, valves, &c.; and on these further experience is needed.

"4. That with proper means of disengaging the train from the piston in cases of emergency, we consider this principle, as regards safety, equal to that appertaining to rope machinery. There appear, however, some practical difficulties in regard to junctions, crossings, sidings, and stoppages at road stations, which may make this system of less general application."

NEW STEAM-ENGINE ERECTED BY MESSRS.

RENNIE, AT MR. CUBITT'S FACTORY,

THAMES-BANK.

The two cylinder expansive engine invented by Hornblower, and afterwards, with but slight modifications, brought into extensive use by Woolf, is well known to all persons acquainted with the history of the steam-engine. The cause, also, of its subsequently falling into disuse is no secret; it was found to perform no more duty with two cylinders than could be done at much less cost with one. Not that more duty was previously done with one cylinder, but that in the progress of improvement it was discovered, or supposed to be discovered, that steam could be worked expansively as well with one cylinder as with two; and so the cost of the second cylinder, and the extra friction and radiation attending the use of it

saved.

Abandoned in Cornwall, where it first found favour, and long maintained a strong hold on public opinion, it has now, strange to say, been reproduced in the metropolis by engineers of the first eminence; and, stranger still, with a degree of success which, if there be no mistake in the case, shows not only that it has been most undeservedly shelved by its Cornish patrons, but that it is in truth the best sort of engine which has ever yet been constructed.

The engine which has thus taken the engineering world by surprise is one which has just been erected by the Messrs. Rennie, at the extensive manufactory of Mr. Thomas Cubitt, Thames-bank. It differs in no respect, as far as regards details and arrangement, from the ordinary rotative engine of Woolf; nor is any such difference claimed credit for by the makers. There are the two cylinders, side by side, as of old-a small one, into which the steam first passes at a high pressure from the boiler, and a larger one, into which it expands (five times); also the ponderous beam, fly-wheel, rotating shaft, &c. The only difference we could observe consists in the workmanship, which is of a very superior description, and in a little better clothing (perhaps) of the cylinders. The effective working power is stated to be equal to 60 horses, and the consumption of fuel to be no more than 2.2 lbs. per horse power per hour. It is this which is the startling result. So small an expenditure of fuel has never been before reached by any rotative engine, of any description; not even by the same sort of engine, when in the friendly and fostering hands of Woolf. That it has been actually realized in the present instance by virtue merely of better workmanship and better clothing, no person can be expected to believe, except on the most indisputable evidence; and such evidence the respectable manufacturers of the engine will, no doubt, themselves allow still remains to be furnished. We were assured that it was doing the same work which two or three old engines, of the cumulative power of 60 horses, had been in use to perform, and have no reason to question the fact; but that, evidently, is a very uncertain test of its real power. We were also shown indicator diagrams, which exhibited a very small average deficiency of pressure; but the insides of steam cylinders and working shafts, as all the world knows, often tell very different tales. The means taken to keep a correct account of the quantity of fuel consumed, (Welsh coal,) appeared to be also most unexceptionable; and if we could only admit 60 to be the proper divisor to employ, we make no doubt of 2.2 lbs. per horse power per hour being a true result.

ABSTRACTS OF SPECIFICATIONS OF ENGLISH

PATENTS RECENTLY ENROLLED.

MILES BERRY, OF CHANCERY-LANE, CIVIL ENGINEER, for certain improvements in the means and apparatus for obtaining motive power, and rendering more effective the use of known agents of motion. (A communication.) Rolls Chapel Office, February 28, 1842.

These improvements, like all the other wonder-working contrivances of this class, professing to obtain power, set all the established laws of matter and of motion at defiance. If any reliance at all is to be placed upon the statements which compose this voluminous specification, the patentee has discovered the long sought-for "perpetual motion;" but he does not seem to be aware of the fact.

The improvements are said to relate to certain means and apparatus intended for the production of motive power, and consist principally in the employment of water, or any fluid, such as air, which is introduced as an agent between the prime mover which acts upon it, and the object against which the force or power ought to act, and by means of the novel arrangement of parts, a better application of motive power is obtained.

A horizontal circular plate, or wheel of iron, wood, stone, or other suitable material, is furnished near its outer edge, with a groove or channel, in which is laid a flexible tube; at short intervals, the horizontal plate is perforated with holes, through which, supplypipes, furnished with valves opening upwards, are led into the flexible pipe before mentioned. The water, or other fluid being supplied under pressure, rushes into and fills the flexible pipe, which is to be very strong and made double, of leather, or other waterproof fabric. A heavy vertical wheel travels round the horizontal plate immediately over the flexible pipe, pressing before it the water contained in the pipe, which is forced through an exit-pipe, and is lead to some suitable machinery to which it gives motion. In the specification, a revolving spiral wheel, on the principle of Barker's mill is recommended— Whitelaw and Stirrats' is no doubt intended.

In order to communicate the requisite

235

pressure, the following novel expedient is resorted to by the patentee; "to the axle around which the weight-wheel revolves, a double steel-yard is adapted, and at the end of the steel-yards, or levers, are suspended certain weights, which by their distance from the point of support multiply the weight! So, that if the wheel be required to press with an effective weight of 8,000 lbs., and the wheel and its appurtenances weigh but 2,000 lbs., a weight of 1,000 lbs. is to be attached to the extremity of each of the two levers: we shall then have for a weight of 2,000 lbs. an effective weight of 6,000 lbs., if the levers from the centres to their extremities are three times the length of the radius of the wheel!!

The advantages of this system are said to be that the application of the power which is obtained by it, allows such power, whatever it may be, to be multiplied ad infinitum, as it has been ascertained, that in order to propel a weight-wheel of 3,000 lbs. weight, (supposing the resistance that the water in the flexible tube offers to its progress is equal to that which motive power encounters on paved roads,) it will be necessary to expend 75 lbs. of power. Therefore, for 75 lbs. of power expended in propelling the weightwheel, a disposable power of 3,000lbs. weight will be obtained by the water at the end of the exit-pipe which water acting, for example, upon a spiral revolving wheel, will allow the latter to propel one or more wheels of 120,000 lbs. weight, which wheels acting on one or more flexible pipes, will generate power by consecutive series ad infinitum ! ! !

:

The Barker's mill is set forth as an example, being considered to give out the greatest useful effect, but any other form of machinery may be employed in lieu thereof; or the issuing column of water may be projected in a jet for extinguishing fires, or for other hydraulic purposes.

For pumps, or fire-engines, the apparatus is to be placed under ground, near the building to be protected.

The apparatus is next shown as applied to the propelling of vessels. In one case, the weight-wheel revolves round a circular plate as before mentioned; in another, it traverses backward and forward, expelling the water alternately from the bow and the stern.

Another form of apparatus is then described; it consists of the cylinder of a steam-engine, which, instead of acting upon a crank to produce rotary motion, acts by means of its piston-rod upon another piston in a second water cylinder, the water being forced through a Barker's mill, or other rotary machine, a little soap being added to the water to reduce the friction!

By this means, says the patentee, a more