less than charcoal well prepared by burning, with a portion of potass, an ingredient to be found in charcoal made from wood, though not always in the proportion required for Joyce's stove.* When the stove was in operation, and the material in a state of combustion, the gas extricated and collected, was carbonic acid gas, as proved by various tests, and by killing birds in a few seconds when exposed to it. Even when the gas obtained from this stove was mixed with (I think) one third of atmospheric air, it destroyed life. The stove experimented on was a single cylinder one. When in operation a piece of linen rag was applied to the cylinder with the view of ascertaining whether it would scorch or burn a similar substance that might either by accident or design be brought in contact with it. The result was, that the linen rag was in a few seconds so singed, that I am persuaded had it been applied a few minutes longer, it would have ignited. The gases evolved had upon myself personally, a very noxious and suffocating effect.

London, April 22, 1838.

C. Q.

HARPER AND JOYCE'S STOVE. Sır,-In the very fair and impartial account of Messrs. Harper and Joyce's "much-talked-of stove," inserted in your last number, the fact of carbonic acid being evolved by the combustion therein, is very properly adverted to, and the unfitness of this stove for carriages, close apartments, and sleeping chambers, clearly and forcibly pointed out. For my own part, I entertain the highest possible opinion of the integrity of the patentees, and firmly believe that the various statements put forth by them, are the consequences of being themselves deceived, and not from any desire to deceive or impose upon others.

There are some points, however, in which they are decidedly wrong; the first mistake, rather an important one, occurs in over-rating the heat-giving powers of these stoves, and it is the more surprising that there should be ambiguity about this, inasmuch as the effect produced by the radiation of heat

We do not think this is the true secret.-ED. M.M.

of a uniform temperature (in this instance I believe about 200°) from a given surface (in these stoves only a few feet) is dependant upon long known and well established laws. This point is one in which scientific men ought not for one moment to be deceived, and yet, the most erroneous statements have been promulgated of the heating powers of this

stove.

The next error-the fatal tendency of which has been more readily perceived and pointed out, is the statement, that the patent stove “is smokeless. and gives out neither smell nor noxious vapour."

The fuel employed by Messrs. Harper and Joyce is charcoal subjected to a certain preparatory process, which is said to enable it to discharge its office, free from the baneful consequences attending its ordinary combustion.

Now, charcoal varies greatly in its character, according to the kind of wood from which it is obtained, varying again not only in trees of the same class, but also in different parts of the same tree. The materials employed in the preparation, are said to be cow-dung and lime, both of them substances liable to greater variations in their component parts than even the charcoal itself. With such materials, therefore, let the operation be conducted with the greatest possible care, it is altogether impossible to prepare a fuel of such purity, with the chemical constituents in such exquisite equilibrium, as to maintain innoxious combustion. Carbonic acid gas will, in all cases, be given off, in greater or smaller quantities, according to the purity of the fuel employed, varying as the elements approach to, or recede from, that perfect theoretical balance of power" upon which the invention is grounded.

But the greatest evil of all appears to me to be, in the temptation held out by the hope of gain, and the facility afforded to fraudulent venders of the patent fuel, for adulteration. The prepared is not to be distinguished by the eye from common charcoal, and when we see the amount of rascality practised in the vending of ordinary kinds of fuel, it is much to be feared that there are dealers base enough to mix, or substitute common, for the patent charcoal.

The consequences of such an admixture, I need hardly tell your readers, burned in a close apartment, would be

certain death. So far as the metropolis is concerned, the patentees may, perhaps, effect the supply of fuel direct from their own depôt; but, should subsequent improvements render the apparatus eligible for general employment, persons residing in the provincial towns, &c. should have some ready means of distinguishing between genuine and spurious fuel. I remain yours respectfully. WM. BADDELEY.

April 23rd, 1838.

ANTI-PHLOGISTIC FLUID, FOR THE PREVENTION AND EXTINGUISHING OF FIRE.

Sir, In the list of patents inserted at p. 464 of your last volume, there is one recently taken out by Eugene Richard Ladislas de Breza, of Paris, for a chemical combination for rendering cloth, wood, paper, &c. indestructible by fire.

As it is scarcely possible to peruse a newspaper without having the feelings harrowed up by a recital of the most appalling accidents from the ignition of female clothing, an unobjectionable mode of rendering articles of dress incombustible, must be peculiarly beneficial.

It may, perhaps, be a pity that any preventive for these heart-rending calamities should be shut up under the monopolizing influences of a patentright. Thanks to British humanity, however, we are already in possession of some simple and tolerably efficient methods of checking the progress of combustion in certain substances. The ingenious Captain Manby, whose exertions in the cause of humanity through a long life of benevolence, entitle him to our warmest gratitude, after having perfected and successfully established his well known plan for "saving the lives of mariners wrecked on lee-shores," devoted a great deal of time to the investigation of the best means of extinguishing or of escaping from fire. Among other branches of inquiry, considerable attention was paid to discover a practical method of increasing the extinguishing powers of water. The result of Capt. Manby's experiments are lucidly set forth in the following extract from "An Essay on the Prevention and Extinction of Destructive Fires, &c." published by him in the year 1830:

"The addition of common pearl-ash, or the pot-ash of commerce, to water, renders

ment.

that fluid capable of extinguishing fire very efficaciously indeed, such is its power, that it will instantly extinguish the flames, nor will the part where it wets re-ignite, or rather re-inflame; for, as the water evaporates, a solid incrustation of the pearl-ash is left on the surface, which by defending it from the influence of air, prevents it from/ burning and from communicating flame to the contiguous parts. Water thus impreg-. nated constitutes what may be called an antiphlogistic fluid which is by many times more effectually extinguishing, than common water. The simple solution of pearl-ash is the one which I have constantly used, and I consider it the best, as it never fails in extinguishing active conflagration. As a demonstrative proof of the efficacy of my antiphlogistic fluid, I illustrated at a lecture, its extinguishing properties by direct experiOn the hand I showed its power of extinguishing flames,-on the other, its property of rendering materials otherwise highly combustible, incapable of burning with flame; and, finally, I contrasted it with the effect of common water. For this purpose I exhibited its effects on the most combustible materials found in dock-yards, viz. : hemp, oakum, cordage, and deal wood; and and afterwards, with a view to diminish the the numerous fatal calamities, that have so often befallen females, from the structure of their dresses, and the inflammable materials of which they are composed-as calico, muslin, gauzes, linen, &c. Of each of these I exhibited a specimen,-the one impregnated with the solution and afterwards dried, the other dipped in common water. By applying fire to each of these specimens, there was at once manifested the value of such an agent in resisting fire."

A knowledge of these facts cannot be too extensively disseminated, as it may providentially be the means of averting some of the worst consequence arising from accidents by fire. By using more extensively stuffs for the external clothing of females, and protecting the linen and calico by means of the simple alkaline solution, the number of deplorable accidents now continually taking place might be materially diminished. I entertain great hopes of much being shortly achieved in this way, as there is some slight symtoms of preventives generally becoming fashionable.

I remain, Sir,
Your's respectfully,

London, April 19, 1838.

WM. BADDELEY.

MINES.

Engine & diam.

of the cylinder.)

North Roskear.

New en

41.4

134

gine; 70 inches; single.

40.0 9

to

Drawing perpendicularly 150 fathoms, the remainder diagonally. Main beam over the cylinder, and one balance bob at the surface. John West.

ditto 3943 374600 8.5

16

92098 74,372,113 8.1

7.

10

March 2498 27097 8.0 95599 80,357,249 6.97 23.

Drawing perpendicularly; main beam over the cylinder; and one bob at the surface. Eustis.

3337 319060 8.75 85530 71.555.445 7.13 Drawing perpendicularly; main beam over cylinder; two balance bobs at the surface; two ditto under ground; and a balance lift in the shaft. Hocking and Loam.

629401660 7.5 15219 73,945,929 8.68 Drawing perpendicularly; main beam over the cylinder.

March 3163 338170 8.0 91364 78,144,960 6.68 31.

to 1240 290050 7.4 41902 72.529,996 9.59 March

Extract from Duty Report of March 1838, for the purpose of showing the Depth, Number, and Diameter of the Pumps attached to several Engines in the Mines of Cornwall. As the eight highest are given, the eight lowest added, will give nearly the average Duty.

BADDELEY'S NAVIGABLE BALLOON.

Sir,-In reply to your correspondent who exhibits such a very pardonable anxiety about a navigable balloon (vide page 44), the discovery of which was announced in your pages eighteen months ago, permit me to say, that I never intended taking out a patent for this invention, the magnitude and costliness of its application rendering such a procedure superfluous.

I was rather desirous of disposing of the invention to any party who would be disposed to take it up in a manner calculated to render the speculation a profitable one. Up to the present time, I have not met with any person so disposed, and the thing remains in statu quo. The experience of eighteen months has in no way tended to shake my confidence in the practicability of the scheme, though I must confess other more pressing engagements have permitted the navigable balloon to receive but a very small share of my attention.

I remain, Sir, yours, respectfully, WM. BADDELEY. April 24, 1838.

MR. UTTING'S ASTRONOMICAL TABLES.

Sir,-In No. 756 of the Mechanics' Magazine, the Cambridge Student has advanced some further remarks on my previous communications, on which, however, it is necessary for me to make but few observations, as the tenor of his epistles are completely on a par with those of the Scotch Dominie. One remark however I shall not pass over, viz.: "Of what use is it to give the length of the tropical periods? It is not from these periods (as the Scotch Dominie has fully demonstrated) that the synodic periods are computed, but from the siderial periods! Let then, Mr. Utting give us a table of the mean siderial periods of the planets, together with the precession of their respective equinoxes, such as he used in calculating his tropical periods, then we would have something to grapple with." (Vol. xxviii, p. 298.) Now in respect to the first, it is evident that the Cambridge Student, as well as the Scotch Dominie, are equally in error, as I have before asserted that the siderial and tropical periods both

"whoever contested such a point." To which the Dominie replies, "I will here tell Mr. Utting that he may now pretend to be acquainted with the abovementioned fact," (mark) "but sure I am, he knew nothing about it until I gave him the information!" I may again here exclaim-What a display of intelligence! These remarks fully prove that you are grounded in the false notion that the above formulas invariably give different results, and moreover, that I was of a different opinion until you gave me the information to the contrary; that is, previous to your information I believed that both formulas gave the same result! A very unfortunate admission on your part, as it completely condems your own arguments and establishes mine, and as I am about to prove. In answer to other remarks of the Cambridge Student, I have given the tropical periods of the planets, with the secular motion of the equinoxial points, from which he may easily compute the siderial periods of the planets, unless he, like the Scotch Dominie, quails at "the drudgery of science"!

Since writing the above I have received part 182 of the Mechanics' Magazine, in which is contained a letter by Kinclaven, confirming all the blunders contained in the communications of the Scotch Dominie. After all the arguments that had been advanced on the subject, he ought to have made himself thoroughly acquainted as to which of the parties was in error; instead of which, he has by an idle calculation subjected himself to a castigation which he justly deserves. (Intended for me too, by the bye). Now the matter in dispute is simply this, whether the said two formulas give, or whether they do not give, the same results?-which I shall now proceed to establish beyond the power of contradiction; as follows: