sold, with the exception of a few copies for friends. Still I complain not, but consider myself well paid; for, as I shall live in heaven, so I shall live on earth as long as it endures.

MR. BABBAGE AND HIS RIVALS.

Sir, In a late number of your publication, I observe that one of your correspondents claims to be the inventor of a calculating engine which will perform the operations of Multiplication, Division, and even do sums in the Rule of Three. As this is a subject in which I take a consi derable interest, I hope I shall be excused if I request a little more information; and first I wish to learn whether this is a self-acting machine, that is, supposing that two numbers are to be multiplied together, is it merely necessary to put them into their proper places, and having adjusted the machine to multiply, to turn the handle until it shall give some signal that the operation is completed? Or when one number is put in as a multiplicand, is it necessary to turn the handle as many times as the number indicated of the

not implicated in the discussion. It is said, "we have just taken notice of Mr. Exley's doctrine of power without substance." Here I state at once, I hold no such doctrine; I never did, it cannot be inferred from any thing I have said; but the contrary may be proved, if need be, from the Treatise of Physics itself. I have every where considered matter as a substance, of course a material substance, really created, and truly and positively existing. It is allowed on all hands, that what we call force, power, or gravitation, is constantly at work; we are assured of this by the effects: now names cannot alter things; what the thing is which we call by these names, no human being knows. I think, but it is merely matter of opinion, that what we call by these names, is not a property but a substance; yet I rest nothing at all on this: if it is not a substance, then I hold it is the property of some unknown substance co-extended with itself. Which ever way it is, I contend equally for a distinct, really created, material substance; I hold no "doctrine of power without substance;" it cannot be inferred from my work or from my theory. I am, therefore, fairly excused from wading through Mr. Cheverton's metaphysical remarks; they apply not to me or to my theory. And as to Newton's little solids themselves, whoever admits them cannot conceive of them, but as a power of infinite resistance, when supported on the opposite side. But perhaps I have already extended my observations to an undue length.

Bristol, May 2, 1835.

THOMAS EXLEY.

I

P.S.-It has been said, a philosopher may be rich if he please; but I presume not by writing new theories. Aware of this, I did not write for gain; but yet thought it enough to give my labour. could not, however, find a bookseller who would undertake the work, but being decided, printed a thousand copies at my own risk, and suffered a loss of 501. This did not deter me from employing my leisure hours for three years to complete the application of my theory to the partly insulated but important subject of optics; and here, again, my success exceeded my expectations; but to show that money was not my object, I published the work at such a price as to leave me 101. minus, should the whole be

multiplier? The question applies equally to Division, and to the Rule of Three, which is a combination of the other two. Also, can it be applied to calculated tables, and if so, how are its results indicated? A machine which when once adjusted to perform an operation requires an assistance from the mind (even the common operation of counting the number of

turns of the handle to know when to expect the result) is open to the objection of liability to error. If one turn be omitted, an error is induced into the calculation, and an error made by a machinė is the more dangerous because unsuspected. I understand that Mr. Babbage's calculating engine is not liable to these objections, and that one great merit is, that its results are the operation of the machine itself, and engraved upon copper plate with unerring certainty. Has the inventor of this new machine taken any steps to make it public, or to secure the patronage of Government? Matters of this kind are of great public interest, and many valuable inventions perish for want of early attention. I trust, therefore, you will excuse my troubling you on the subject.

I remain, very truly yours,
P. S. C.

METROPOLIS PURE SOFT SPRING-WATER

COMPANY.

"Nos monendi causâ pauca esse dicturos."-Cic.

Sir,-An advertisement in this morning's paper announces, that a bill for the incorporation of the above Company has been read a first time in the Commons.

The projectors of this concern proceed upon the ASSUMPTION, that the London basin contains a subterranean lake, and an INEX. HAUSTIBLE supply of water.

The result of four trials in the manufactory in which I am engaged, namely, two large wells and two bore-holes, leads me to doubt the correctnes of the ASSUMPTION, "that the supply of water from the main spring is INEXHAUSTIBLE."

For these wells having been constructed at different and at distant periods, between 1810 and the present time, the supply of water, though at first abundant IN EACH of them, has gradually and uniformly diminished IN ALL.

The principal well, nearly a new one, obtains its supply from the whole of the thickness of the quicksand; for the lower end of the bore pipe, which terminates with a teninch opening, is bored full of holes for the last thirty feet, and rests upon the face of the chalk. Hence we secure the fullest capabilities of the spring through the whole depth of the quicksand.

This well was pumped for months, night and day, without intermission; and the quantity of water yielded was so great, that the supply was considered to be inexhaustible.

Nevertheless, after a time, the spring grew gradually weaker; and during the last summer (1834) the water was repeatedly drawn down to the suction-guard, which is ninety feet from the surface, and the engine was obliged to stop continually, to give time to the spring to replenish the well by infiltration from the quicksand below.

Many of our largest manufacturing establishments are similarly dependent upon the deep springs for their supply of water; and therefore those who are so circumstanced, have a right to ask from what source they are to expect compensation, should this Public Water Company cut off their supply of water, to the complete destruction of their property, by rendering useless their buildings, plant, and utensils, and utterly annihilating their trade, for want of the necessary supply of water to keep them going.

It must be borne in mind, that, to render this new speculation available to the shareholders, the quantity of water to be raised must necessarily be enormous as well as incessant; and when it is mentioned, that after some hours' pumping at one of the wells

under my consideration, it lowers the water considerably in another well three miles distant in a direct line, and that it requires nearly double the time for the pumps to stand still in the first well before the other recovers its level-I trust it will be admitted that the assumption of an INEXHAUSTIBLE supply requires some further elucidation; and it is to be hoped, that before the legislature give their sanction to such an experiment, they will obtain satisfactory proof that they do not hazard thereby the supply essential to the existence of many of the most extensive establishments in and about the metropolis, and involving hundreds of thousands of pounds of capital irrevocably and irreme. diably sunk.

If you'd be weather-wise, attend
The plain instructions of a friend,
Who will with certain signs explain
Which promise snow, or hail, or rain:
By which you may, with prudent care,
Against a stormy day prepare.

Since various tokens bounteous Heaven
For mankind's use hath kindly given,
Contemplate with curious eye,
And study how to read the sky.

If blue the morning sky appear,
The day will be serene and clear;
But if red clouds with black prevail,
Expect a storm of rain or hail.

Whene'er the moon, night's silver queen, Is hid by clouds of darkish green, And stars, just seen, appear to low'r, Depend you'll have a heavy show'r.

If in the sun or moon appear Black spots, although the sky is clear, Be sure a storm is very near; And if the beauteous rainbow's seen, Where mild weather is serene, Bleak winds will quickly change the scene.

If a prodigious cloud you spy, Pass quickly on, though very high; The wind will bring a storm of rain, And blow a dreadful hurricane.

When the sun's beams are broad and red, Some boisterous weather you may dread,

Whene'er the evening is serene, And in the east the rainbow's seen, The following morning will be fine, And the bright sun unclouded shine.

When flashing quickly through the sky You see the forked lightnings fly, And cannot yet the thunder hear, Expect fine weather to appear.

When in a clear, but wintry, night, The stars are twinkling large and bright, And the black clouds in fleece are lost, Depend you're threaten'd with a frost.

When winds irregularly blow, And dingy clouds pass to and fro, You may expect a deal of snow; And if you find no morning dew, Be sure cold weather will ensue.

If round the moon a circle's seen Of white, and all the sky's serene, The following day you may divine' Will surely prove exceeding fine.

Whene'er in autumn, or in spring, A mist the moon doth with it bring, At noon the sun will bright appearThe ev'ning be serene and clear.

In winter, store of rain and snow A spring and summer fine foreshow; But if too mild the winter's found, Diseases will in spring abound.

THE PNEUMATIC RAILWAY.

Sir, In noticing the remarks which you have hazarded upon the Pneumatic Railway in your 612th number, I will not dwell particularly on the obvious charge to which you have subjected yourself, of gross ignorance or of unprovoked malevolence, and will only stop for a moment to admire the temerity of the Editor of the Mechanics' Magazine, in opposing his opinion to the opinions of two of the most eminent men of science in England. Such a display of ignorance may have been made to gratify malevolence, or malevolence may have induced the display. When you announced in a previous number, that

the

pneumatic railway should have "full justice" done to it, Mr. Hosking, who is professionally interested in that

railway, wrote to you, offering to show you our working model, and to afford you such information, as would enable you fully to comprehend the system to which you had promised to do "full justice." I also informed you that, for reasons which I then assigned, all the details of the system could not yet be published. In your answer to Mr. Hosking, you declined his offer, believ ing, as you said, that you were already in possession of every information requisite to enable you to form a sufficiently accurate estimate of the merits of the scheme. If you really possessed such information, you certainly have not given your readers the benefit of it.

Your great objection to the pneumatic railway, is founded on Papin's supposed failure in his experiments to which you have referred. I think that you ought, in candour, to have given credit to the source from which you have derived your information,- Encyclopædia Britannica," vol. xiv. p. 719. Many of the theories on the science of pneumatics, which were advocated in the older and sometimes even in modern works, are shown by practice to have been founded in error, and are, consequently, at this day, abandoned by all scientific men who are really well informed.

What Papin proposed to do, and failed in effecting, through the imperfection of his means, most probably, is now constantly done, and with the utmost efficiency. Mr. Hague, the ingenious engineer of Cable-street, has succeeded in applying the principle suggested by Papin, and is daily constructing engines which communicate their power by the rarefaction of the air in close tubes, and tubes of small diameter, too, to distances of three, four, five, six, and even seven miles! At the mines of Mr. Brown, near Manchester, Mr. Hague has erected four sets of apparatus, all of which are worked by one steam-engine of seventyhorse power, and one of thein being at a distance of three miles from it. Mr. Hague has assured me, and you, or any of your readers, will find it on inquiry, to be strictly correct, that, notwithstanding the smallness of the tubes through which the transmission is made, and the consequent great extent of rubbing surface in them, together with the numberless flexures with which they are laid, the whole power of the engine is trans

mitted to the work, and this at a degree of rarefaction equal to a column of from seven to ten inches of mercury! In fact, the mercury is, in these works, found to stand at exactly the same point at both ends of the same tube, and the transmission of the impulse through the longest of them, which I have already said, is three miles long, is so nearly instantaneous, as to render it difficult, if not impossible, to detect the difference in time. This, however, is not a singu lar instance. Mr. Hague has erected similar machinery upon the same principle, and acting in the same manner at long distances, in Cornwall and in other parts of England. One set of his appa ratus has been in operation in the works of Mr. Foster, at Stourbridge, for the last six years, and without requiring any important repair throughout that period. Not less than a dozen establishments in Holland, and as many as fifty in various parts of Mexico and South America, will testify to the successful application by Mr. Hague, of the means which Papin attempted to use, and failed in effecting. The first mover, I may add, is sometimes wind, sometimes water, and sometimes steam.

Now I do not know whether it was through ignorance or malevolence that Mr. Hague was opposed, but he had to struggle for many years against one or the other, or it may be both, to procure the adoption of his mode of communicating power to a distance by the rarefaction of air within tubes. He had, as I have, to contend against the influence of quid nuncs, who can quote exploded falfacies, the ill-will of thwarted officials, and the opposition of interested machinists who procure themselves to be thought mechanical philosophers!

Your other case from the "Encyclopædia Britannica"--that of the attempt to force air through a tube to form a blast at the Eagle Foundry in Wales-is not in point, as that was to act upon a plenum, and not with a vacuum, ás in the case in question; but it is disposed of, nevertheless, by what I have yet to call your attention to.

You state that "the grand difficulty to be overcome" is the "difficulty of acting on a column of any considerable length, of so thin, subtle, and elastic a fluid as air." The practice of Mr. Hague's apparatus, above referred to,

clearly proves that no difficulty exists in acting upon it to a much greater extent, and under much more disadvantageous circumstances, than the pneumatic system of railway requires or imposes by rarefaction; and the practice of gaslighting as clearly proves that a column of considerable length, of a thinner, more subtle, and more elastic fluid than air can be acted upon to any extent, and to any effect that may be required. To any of your readers who think for themselves, the fallacy-not to say falsehood

of your assertions, if they reflect at all upon what is constantly before their eyes, must have been sufficiently obvious. It will be within the recollection of many, and may be known to all, that, when gas-lighting was first proposed for general application, it was declared by the pseudo-philosophers, and Editors of Mechanics' Magazines of the day to be impracticable, because of the difficulty of passing so "thin, subtle, and elastic fluid" as gas in sufficient quantity, and with sufficient velocity through tubes; as it was asserted that the mains must be so large and costly as to make the application unprofitable, even if it were practicable. But during the last twentyfour hours in London alone some millions of cubic feet of gas have been passed through mains and pipes of small diameter, at a distance of many miles from the works at which it is produced, with the greatest required velocity, under a pressure at the works of-what immense force do you suppose, reader? a column of, upon an average, two inches of water! I need hardly refer you from London to Birmingham, but that this latter affords a striking popular example of the practice of passing gas through tubes for long distances. Birmingham is lighted with gas brought from West Bromwich, a distance of seven miles; in mains; and the "thin, subtle, and elastic fluid" is ejected at Birmingham, with nearly the same force as that which is applied to it at West Bromwich.

Now what shall be said of the erudition of the editor of a scientific journal, who is ignorant of the facts herein related? And what shall be said of his candour and honesty, if informed of them he make a garbled mis-statement to repress the enterprise, and injure the property of one who has not called upon the public to aid him in maturing and

exemplifying a useful invention; but has, at his own cost, and by his own exertions, matured and exemplified that which many of the wisest, noblest, and worthiest in England have already recognised as useful and valuable?

Having thus given your readers an opportunity of judging between us upon those matters on which you appear to speak with authority by quoting instances, I am quite willing to trust to their candour and general good sense not to receive your dictum upon the details of the pneumatic system of railway, of which you declined the proffered infor mation, and about which I may assure them you are totally ignorant; for, indeed, I believe that, by the time they have read thus far, they will conclude it to be possible that Professor Faraday and Dr. Lardner may have formed as correct an opinion of a matter they have inquired into, as the editor of the Mechanics' Magazine of that, of the principles and practice of which he is alike ignorant.

I am, Sir,

Your obedient servant, HENRY PINKUS:

Remarks:

Mr. Pinkus is pleased to admire the te temerity of the Editor of the Mechanics' Magazine, in opposing his opinion to the opinions of two of the most eminent men of science in England," Professor Faraday and Dr. Lardner. But one-half, at least, of this admiration might very well have been spared. Professor Faraday's is no more an opinion in favour of Mr. Pinkus's scheme than is ours. It amounts merely to this, that if you produce a vacuum, or partial vacuum, on one side of an airtight diaphragm or piston inserted in a hollow cylinder, you will obtain a corresponding pressure on the other—a position which no one acquainted with the first lines of science can contest. But whether this principle of obtaining power can be turned to any profitable accountwhich is the whole matter in disputethe Professor does not say-indeed, he expressly declines saying. Dr. Lardner, to be sure, is not so scrupulous-he subscribes very unreservedly to all Mr. Pinkus's odd notions on the subject; but though we hold Dr. Lardner's acquirements in considerable respect, and his talents in still more (talents equal, pro

bably, to the achievement of any degree of distinction, if they were but under the guidance of a little more discretion), we must be permitted to say, that his authority, as a man of science, is not just yet of so overtopping a description that it should be considered " temerity" in us to differ from him; indeed, if coupled with many more such opinions as the present, it will never be worth any thing.

Mr. Pinkus states truly, that we declined Mr. Hosking's offer of a personal explanation, on the ground that "we were already in possession of every information requisite to enable us to form a sufficiently accurate estimate of the merits of the scheme;" but he adds, not quite so truly, "if you really possessed such information, you certainly have not given your readers the benefit of it." The information which we possessed, and gave our readers the benefit of, consisted, 1st, of Mr. Pinkus's own Prospectus of his scheme; 2d, Dr. Lardner's elaborate commentary upon it; 3d, The Professional Director, Mr. Hosking's, explanatory letter to Professor Faraday; and 4th, Professor Faraday's reply. Now, not only are these the very documents referred to in the advertisements of the "National Pneumatic Railway Association," for evidence of the "practicability and efficiency of the pneumatic system," but they comprehend the whole of the information, neither more nor less, which has yet been given to the public on the subject. If, therefore, we have failed to furnish our readers with information enough on which to form a 66 sufficiently accurate estimate of the merits of the scheme," the fault lies not with us, but with Mr. Pinkus himself and his friends; and it follows, too, of necessity, that they must be practising a very considerable imposi tion on the public, in opening a subscription for 200,000l., on the strength of documents, from which, according to this view of the case, no 66 accurate estimate of its merits can be formed! Which horn of the dilemma would Mr. Pinkus be pleased to prefer?

66

But I also informed you," says Mr. Pinkus, that, for reasons which I have assigned, all the details of the system could not yet be published." Yes, Mr. Pinkus did say something of this sort; but, on the very same morning, advertisements were to be seen in most of the newspapers, soliciting subscriptions to