composed of flat chambers is publicly used, there is no legal invasion of my right; and it is by no means the first time that I have been placed in precisely the same situation in regard to these flat chambers; but, as the parties alluded to employed my invention only in experimental, and, ultimately, abortive attempts, I had no occasion to interfere ;and with regard to these experiments of Sir James Anderson with my flat chambers, I fully expect they will have the same result. I tried the flat chambers, placed so as to form one continuous flue, in a carriage eight or ten years ago, and therefore know well the merits of such a mode of arranging them. If Sir James Anderson had had one-twentieth part of the practice with flat chambers that I have, he would not have ventured any public announcement, even of experiments with them, thus arranged, until he had tried how his carriage would perform over a good run of new-laid gravel or a rugged steep. I quite agree that "there is room enough, Sir, in England for us all;" but let every one in so noble a race bring for himself the resources of his own talent only, and make it a point scrupulously and honourably to stand clear of the discoveries and combinations wrought out by his competitors; and if these discoveries and these combinations have resulted from years of labour and expense, let that circumstance render them so much the more sacred in the estimation of a keen but generous rivalry, whether they belong to a Gurney, a Maceroni, a Sir James Anderson, or Your obedient servant, W. HANCOCK.

MR. HANCOCK'S STEAM-GIG. Sir,-Being in the park last Tuesday afternoon, I had, for the first time, the gratification of seeing Mr. Hancock's steam-gig, and of noticing its perfect operation and evolutions, during the whole time it was there. This brought to mind an inquiry I wish to make: -is the theory laid down by Mr. Baddeley in your last Number correct-that "the weight of the locomotive increases in a much quicker ratio than the power"?

I must confess my disbelief of this; surely an engine and boiler of 80-horse power does not weigh so much as two separate

engines and boilers of 40-horse power each. I have always understood, that the little dependance to be placed on the results of small working models, arose from the very reverse of his position.

Residing in the district, I have frequently rode on Mr. Hancock's carriages, on the Paddington Road, and I most cordially wish him a due reward for his ingenuity, and years of perseverance, which perhaps he may now stand some chance of, as, I understand, the gig was worked in the park by the express desire of some of the distinguished foreigners now in London. Prince Puttbuss, the Prussian Ambassador, the Prince of Hanover, the Hanoverian Ambassador, and several ladies, rode upon it at different times; it was also minutely inspected by Prince George of Cambridge, Duke de Nemours, Marquis Milleflores, Prince Pattrass, and many other foreign nobles, whose names I did not hear, and who all expressed their admiration of this neat and effective little piece of powerful mechanism.

Most heartily do I hope that, now Mr. Hancock has brought his carriages to a state of perfection fit for public use, he will not be surrounded by a host of pirates, as is too frequently the case; but of this I have my fears, from perusing your pages of the 16th ultimo, in which a description of Sir James Anderson's boiler, composed of "broad flat waterchambers," is given.

This boiler differs from Mr. Hancock's only in two points--the steam-chest, or separator, and the direction given to the heat, both of which are so disadvantageous, that Mr. Hancock, or any other practical man of talent, would not adopt either of them; and this anticipation or fore-knowledge of failure, I suppose, accounts for Mr. Hancock's supineness in not noticing the invasion of his invention. I am, Sir, your very obedient servant, AN AMATEUR MECHANIC. Islington, July 19, 1838.

draw a weakly stock of knowledge, Sympathy would suffice to prevent my being too hard upon the "Tyros," who occasionally try the strength of their pinions in this atmosphere, and their puerile attempts would have passed unnoticed and uncommented upon by me, had not one audacious stripling endeavoured to fire off a great gun, to astonish his compeers by the magnitude of his calibre. This daring performance has been achieved by pilfering a ready made article" from one of your back numbers of four years standing.

In No. 588 of the Mechanics' Magazine, published November 15, 1834, there appeared two engravings and a description of an "improved floating fire-engine," which I had designed some time previously. The last number of the Penny Mechanic contains a copy of these two engravings on the frontispiece, with my article appended, almost verbatim from your pages. All the circumstances which I enumerated-all the alterations I proposed and all the improvements suggested-have been re-stated, re-proposed, and re-suggested by a Mr. J. E. Goddard!

The deviations from my words are few and unimportant: there is one paragraph, however, which this wholesale plagiarist has not had the effontery to transcribe. It is that which sets forth the fact of my being employed by Mr. Buston to examine and improve the floating fire-engine of the London Assurance Corporation, of which he was foreman. I suppose Mr. J. E. Goddard thought that to repeat this statement as his own, would at once stamp him "the lying'st knave in Christendom," though for my own part, I can see but little difference in criminality between this and what he has really done. In reiterating my words Mr. Goddard subsequently says,

the floating engine I allude to, &c," forgetting that he had omitted the allusion referred to His reference to "the late tremendous conflagration at the House of Lords," looks particularly silly at this distance of time; especially after the building of a powerful floating fire-engine by the London-fire-establishment, together with the occurrence of several serious water-side fires, at which it has been eminently useful.

In consequence of some errors in the punctuation, that which was originally

sense, is converted into nonsense, and taken as a whole, this is one of the most disgusting and disgraceful acts of plagiarism I ever met with.

Älthough for the present superseded, my plan assumes considerable importance, inasmuch as I have been informed, that in some respects the new floating engine has disappointed the expectations of its designers, and that in the event of another being built, several of the improvements I have suggested would be adopted.

I remain, Sir, yours respectfully,
WM. BADDELEY.

London, July 17, 1838.

Mr. Baddeley, whose numerous contributions to your valuable Magazine are distinguished for their usefulness, and their constant tendency to promote the public interest, as well as for a propriety of language, is very likely to be correct in his expectations, when he asserts, in mentioning the formation of an honorary fire-brigade at Cheltenham, that " these voluntary associations are likely to be productive of incalculable good." These associations, which have been known on the continent for some time, are certainly worthy of every encouragement which public confidence can bestow on them. Some details respecting their organization in Switzerland, which have come to my knowledge during a residence in that country, may perhaps not be deemed unworthy of notice at the present mo

ment.

Honorary fire-brigades are already organized in Switzerland, not only in small towns and cities, but even to a great extent in villages. The most reputable citizens vie with each other in eagerness and zeal to become members of so useful associations, which, however, consist of a fixed number of men. In some places the members are divided, some devoting themselves exclusively to the management of the fire-engine, while others are charged with the not less important task of taking immediate possession of the house on fire, in order to carry off, and convey to places of safety, the furniture and other moveable property which it may contain. Large and

very convenient bags, with which they are often provided, enable them to save also most of the minor articles, which would probably otherwise become a prey to the flames. None but members of the brigade are allowed to enter the house; by this wise regulation, men of a bad character are entirely prevented from exercising their disgraceful industry on such occasions, while the order and method with which the praiseworthy exertions of the fire-brigade are conducted, are certainly productive of the greatest benefit to the poor sufferers. It is but justice to state, that on all occasions these exertions meet with due encouragement from every one capable of appreciating the self-devotion and generous feelings of the spirited citizens forming the honorary fire-associations.

Before I conclude, I beg to be allowed to make one more reflection. It sometimes happens in this country, that fireengines cannot be put in action immediately on their arrival, because no water can be procured, the man who has charge of the key of the water-plugs not being on the spot. Now, in Switzerland, two or three keys are distributed to an equal number of persons living near the house where the fire-engines are kept; so that, in want of one key, there may always be procured another in any case of emergency. It is evident that the application of this principle to the water-plugs of the metropolis would be as beneficial as easy. It would, indeed, be quite needless for me to dwell on the advantages which would undoubtedly accrue from such a practice being adopted. I shall, therefore, only add, that

I have the honour to be, Sir,
Yours respectfully,
P. OBER.

Twickenham, July 20, 1838.

SINGULAR FACT IN FALLING BODIES.

Sir, I have observed that a piece of stiff writing-paper, three inches long by an inch wide, held up as high as a man can reach, and extended between the fore finger and thumb of each hand, and then let loose in a room, when the doors and windows are shut, will always revolve on its long axis. This fact I mention in the hope that, in this age of mental exercise,

In all such observations, the annual motions must be allowed for, and so reduced as if there were no such motions. Let this be done, and let A B be an arc of the Earth; V, Venus; and S, any point in the sun with which V is in conjunction, as seen from B; but from the observer at A, the point S appears in the direction AS, and Venus in the direction A V, where V will fall on a different part of the sun. Here angle A V B is the parallax of Venus, and angle ASB that of the sun. Now angle SAV is the only observed angle, and its position is unknown; whence A S was treated as if parallel to B S, making the alternate angle AV Bangle SAV, and whence the sun's distance as if infinite; but since the sun has a parallax, AS and BS must meet at S, and form a triangle A S V, whose outward angle, A V B, is greater

than either of the inward angles, SA V or S,.. the angle S is equal to the angle A V B, less by angle S A V, which gives the difference of the parallaxes, and not the parallax of either the sun or Venus. Thus treating A S as parallel to BS, the angle AV B measures too little; and hence A V or B V are too much for venus's distance; which, compared with the known ratio of the distances of the primary planets from the sun, make their distances and magnitudes too great but if S was a fixed star, then A S would be parallel to B S, and angle S A V, and angle A V B would be equal, and would be the correct parallax of Venus. The ancients found the earth's distance from the sun to be 81 millions of miles, and this I find correct; and am, Sir, your humble servant,

May, 1838.

WILLIAM SHIRES, Teacher of Mathematics.

MILLS'S MERCURIAL PUMP NOT NEW,

AND USELESS.

Sir,-Perhaps it would be too much to expect that every projector who may send his little nursling to encounter the rough ordeal of your Magazine, should previously be conversant with the history of the branch of science to which it may belong; nay, even the most absurd pretension to originality may be treated with indulgence, provided it be put forward with a due degree of modesty and diffidence; but the case is otherwise when we are told that a learned lecturer on natural philosophy, who ought, ex officio, to be deeply read in his vocation, has adopted the invention as a class-subject, and edifies his pupils by a model of the discovery!

It is almost needless to say, that this observation bears reference to Mr. Mills's account of his mercurial pump, contained in your 776th Number, page 190. Had Mr. Mills read an article on pumps in the Encyclopædia Britannica, (which book I particularize because there is scarcely any person to whom it is not accessible), he would have soon found that he has not a single particle of claim on the pump he has so charitably adopted as his own ;-that it was invented and abandoned for its many defects upwards of a century ago;-and that the only dif ference between the pump there des

cribed and that invented by Mr. Mills is, that the arrangement of the parts is slightly different, the moving part in Mr. Mills's being an empty, unweighted, unsteady vessel; while in the original invention (by Mr. Haskins) the vessel containing the mercury, rendered steady by its great weight, is the moving part; -the latter arrangement being so greatly superior, and so much more elaborately contrived, that it is an almost unavoidable inference that the plan used by Mr. Mills was first tried, and the other afterwards adopted as an improvement upon it. But, as if to deprive Mr. Mills of the loop-hole of escape which even this slight difference of arrangement might afford him, the description of Haskins's pump concludes with the following remark :— "It is on precisely the same principle as the cylinder bellows described under the article Pneumatics;" and the cylinder bellows, so referred to, is the exact counterpart of Mr. Mills's pump, the arrangement being there not so objectionable.

But the concluding remark in Mr. Mills's communication is of such trans→ cendent genius, that it throws the rest far into the shade: he says, that one advantage possessed by his (?) pump is, that " for every inch of stroke of the handle K, the water will be raised one foot high!" This piece of unmitigated absurdity proves, as clearly as the noonday, that Mr. Mills has seen the description of Mr. Haskins's pump, and has copied it as his own invention, without understanding its principles: in the said description it is stated, that for every inch difference of height between the inner and outer cclumns of mercury, there must exist a difference of a foot in the columns of water, the former being twelve times heavier than the latter. Now, does not the sentence from Mr. Mills's letter, quoted above, furnish internal evidence that this part of the description of Haskins's pump must have been travestied in Mr. M.'s brain, without his having understood its meaning? else, why should he adopt one foot and one inch-13, and not 12, being now the acknowledged specific gravity of mercury?

In fine, although Mr. Mills's model may form a very pretty squirting-toy for Mr. Grier's lecture-table, it is equally valueless, whether as an original invention or as a practical machine.

NAUTILUS.

Sir-From the non-appearance of my letter of the 3rd inst., respecting Mr. Mills's pump, I conclude that you considered it anticipated by Mr. Baddeley's communication on the same subject in No. 778, page 231. I freely acknowledge that Mr. B. was fully entitled to the preference, as well from priority in the date of his letter, as from his known experience in the world of hydraulics. I took, however, quite different ground from him; he confining himself to objecting to the practical efficiency of the pump, while I directed my remarks to its total want of originality; in fact, all the objections adduced of Mr. Baddeley may be found in any of the many treatises wherein the pump of Haskins is described.

There is, however, one most extraordinary blunder, into which Mr. Baddeley has fallen, and which I sincerely regret, as it may afford a peg to Mr. Mills or his friends whereon to hang an apparently successful answer to his letter. It is that part wherein Mr. Baddeley says that Mr. Mills's pump is of the lifting, and not of the suction kind, as stated in Mr. Mills's description.

Now, that the contrary is the case, is an axiom so palpable to any one who has glanced at the rudiments of hydraulics, that to attempt to prove it by any serious argument is almost puerile; but, when such an authority as Mr. Baddeley is supposed to be, writes it, not as a random assertion, but as a grave accusation of want of correctness in description, a few words in proof of his egregious mistake may be excused.

A lifting pump, then, is that wherein the piston acts entirely beneath the surface of the water to be raised; for, if the piston act in the least above such surface, the pump partakes of the suction kind. Ordinary pumps, with a valve in the piston, are of this mixed nature, -the water beneath the piston being sucked, or supported by atmospheric pressure, while that above the piston is lifted.

Now, it is evident, that in the mercurial pump, decscribed at page 190, the piston being 30 feet above the surface, it is, in its up-stroke, altogether of the suction kind, and, in its down-stroke, of the force kind: the term lifting force-pump, which Mr. Baddeley has conferred on it, is, therefore, glaringly wrong; while the

STEAMING ON CANALS- ERICSSON'S PROPELLERS.

We copy from the Manchester Guardian the following account of a very successful experiment made on the Duke of Bridgewater's canal with Mr. Ericsson's propellers, described in our 751st Number. The account is defective and erroneous in many particulars, and in none more so than in the ascription of all "the merit" of the affair to Messrs. Robins and Co. (the well-known carriers), and the apparently studious omission of the name of the ingenious and indefatigable inventor, Captain Ericsson. We have subjoined, therefore, some notes which may help to set the matter in its true bearings before the public.

As our American neighbours would say, we are going a-head" in the use of steam as a locomotive power. But a few weeks ago we noticed the starting of a small steam boat to ply on the Irwell, with passengers, between this town and Warrington; and we have now to announce the application of steam to carriers' canal boats for the transit of goods between this town and London. In canal navigation in this country, a long period of time has elapsed since any alteration or improvement of any great importance has been made. The boats are of the same construction, and so inartificial is the mode of working them, that the only means in practice, at the present day, for propelling them through the immense tunnels, of which one is nearly a mile in length and another three quarters of a mile, is for the boatmen to lie on their backs on the tarpaulin which covers the goods with which the boats are deeply laden, and, by pushing their feet against the roof of the tunnel, work the boats onwards at a tediously slow rate, with great labour and fatigue, amidst the smoke from the boats' chimneys or funnels, which, to any one unused to its effects in a long tunnel, would seem wholly unendurable. This is what the boatmen term "legging through ;" and in this way