of the peculiarity of the river steam-boat. If I have omitted any details which are interesting, I trust some of your friends will take the trouble of requiring explanation on the subjects omitted. Details of cost of engine, boat, cabin, &c., I cannot furnish from want of specific accounts; but these could be of little use, for the prices not only vary in the same place at different times, but differ constantly between different places. Neither can I tell the wages of officers and men, prices of wood, rates of freight, all of these changing and differing at different places and in different seasons, &c.

Should you think these remarks worthy of a place, I may in another paper furnish you with some hints on the navigation of the Atlantic by means of steampower, a subject which, I think, has not been considered in its proper bearings. I have some hopes of being able to give an opinion on it, having been made well acquainted with its navigation during more than one voyage, and having stu died and examined carefully the advantages and disadvantages of all kinds of steam-craft, and steam-boilers, and engines, both fixed and moveable.

This subject will involve us in the consideration of the shape or build, rig, and general fitting-up of the vessel or packet, so that it will sail well and pleasantly; that it will expose the least surface to the resistance of water at all times, and least resistance to the wind when adverse, and most when the wind is favourable; the greatest levity and strength, consistent with safety which will depend on the nature of the materials used in the construction; the lightest and most heating fuel, and best construction of boiler. Indeed, I think I can make out a good case, or, I should say, a better than has yet been made out, which may be improved upon; but this is "what I want to be done.

Until my next, which will require a few drawings, I must bid you, Mr. Editor, farewell, thanking you particularly for the pleasure and information I have received from the perusal of your last two or three volumes, which only came to my hands within the last few weeks.

Fig. 1 represents a section of the improved cowl, which is constructed as the common cowls are, so far as regards the general principle of the revolving of the lateral on the vertical parts of it; but instead of the end opposed to windward being, as is usual, closed, a funnelshaped apparatus is introduced, terminating in a pipe of about three inches diameter, which is carried just over the Opening of the vertical chimney-pot. The effect of this is, that the lateral pipe of the cowl being by the operation of the wind on the vane always turned endwise in the direction of whatever current of wind may happen to be strongest at the time, a draught is created by the wind rushing through the funnelend of the cowl-top, and the smoke is thereby, with considerable velocity, carried completely out of the cowl. The

COOKING BY GAS-REPLY OF MR. BEALE TO MR. BARLOW.

Sir,-Although I was perfectly satisfied in my own mind, that the charges in my last letter against the infringers of Hicks's gas-cooking patent were unanswerable, nevertheless, some of your readers might suspect from what was announced in your Magazine, No. 635, that Mr. J. Barlow was going to refute them. On the contrary, I find he has done no such thing, My " grave charges made on weak grounds" bring to light, that part of Mr. Barlow's gas-cooking apparatus cost 31. in the City-road, though he had stated on September 5th, that Mr. Sharp of Northampton supplied him with it for 51. I leave it to the public to judge how these two opposite statements are to be reconciled. That endeavours have been made to "spread abroad a motion that cooking by gas is not the subject of a patent," is not denied. The very language made use of implies the exist ence of what the interloping parties would fain conceal. Mr. Barlow's apparatus is called "Sharp's Improved." Now what is it he has improved " upon? On Mr. Hicks's invention, of course-if improved it be, which I deny -though of this the original invention, not one syllable was said. In short, not one satisfactorily proved negative is given to any

of my assertions-not even to cooking by gas, with an envelope, being Hicks's patent; for I would give Mr. Sharpe to understand, that I call a conical hood an envelope; although Mr.

3

T. G. Barlow asserts, that it is an arrogant assumption, I do attack the use of gas for cooking under any sort of envelope, hood, or cover as an infringement of the patent.

Although Mr. J. Barlow may not term himself an inventor, yet Mr. T. G. Barlow seems to claim the having given to the Americans a "rough idea" of roasting meat under a metallic cone. Pray, why did Mr. Barlow endeavour to seek out Mr. Hicks when in America; or how could he know that Mr. Hicks was in America at all, and that he was the patentee of this, invention, if he had not pretty well investigated the matter before he left this country? He could not have come to all this knowledge without knowing the principle, the ap plication, and the form of Mr. Hicks's patent apparatus. I wish he would say what points those are in which Mr. King ought to be set right, because, as I before stated, any one may see that the extract from the New York American, and Mr. Loudon's description in No. 495, are nearly synonymous. All that Mr. T. G. Barlow has stated, tends to verify what I said before on this head. The only excuse he offers is, that he made use of a metallic cone as "the cheapest and least troublesome"!! Ile says, also, there can be no great crime in not naming Mr. Hicks as the inventor and patentee," for the defects of Hicks's apparatus must be apparent to all who have witnessed its operation," &c. But why not tell us what these defects are? And why did he make use of such a defective apparatus in America? Oh, because it was the "cheapest and least troublesome "!! Yes, truly, and he might have added, the one also in which the fuel is most economically applied.

At the commencement of Mr. T. G. Barlow's letter, Mr. J. Barlow is styled "a humble individual," who, 66 without the remotest prospect of personal gain, desires to increase the public conve nience;" and at the latter part of the same letter we are told, that he is ready to go to law. He must be very philan thropic if he would go to law for the public convenience merely.

Again, it is stated, "Mr. J. Barlow's object was not to recommend either this or the other machine." But how does this agree with his letter, which ap

peared in your Magazine on the 5th of September?

"The whole matter," says Mr. T. G. Barlow, "resolves itself into a dispute between the inventors of two rival apparatus." Not so; but into a dispute, of which this is the sum and substancewhether a person who only claims to have improved on the invention of another, is to be considered as himself the original inventor?

Mr. Ricketts and Mr. Sharp are, according to Mr. Barlow, "the only persons who have really constructed an effective and economical apparatus." But as regards Mr. Ricketts, he has owned, and I can prove it, that he borrowed his from Hicks's,

It is to be remembered, that Mr. Hicks's is an original invention; and admitting, for the sake of argument, that either Mr. Sharp or Mr. Ricketts have improved it, they cannot legally make use of it without the consent of the proprietors of the patent. Could Messrs. Boulton and Watts have been robbed of their patent by any one that had constructed an engine with a square vessel instead of a cylinder; a square piston rod or square air-pump? Certainly not. Neither can any one justly deprive Mr. Hicks or his assigns of his invention, because the envelope they make use of is square or otherwise, I feel no hesitation in saying, that they would find some difficulty in proving themselves legal pirates, sharp as they might be.

Does Mr. Barlow think that the patentee was such an arrant fool as not to have claimed a cylindrical, or cubical, or any other shaped hood (or envelope, whichever Mr. B. may please to call it), if such was legally necessary? I beg leave to inform Mr. Barlow, that Mr. Hicks tried experiments on all those different forms, and on different kinds of burners also, and concluded, that the form shown in his specification was efficient, which is all that the law requires, viz. for one efficient method to be shown; otherwise his specification would have reached from here to Northampton, and it might have been necessary to state in it, that a calf's-head or other viands might be cooked within a hat or a bushel, &c. &c.

But it is useless to swell out these pages with a matter which I can very

plainly see will have to be decided elsewhere. I feel obliged to you, Mr. Editor, for the space you have hitherto allowed me.

Many of my charges appear to have fitted Mr. Barlow, as he seems to have taken them upon himself, and may be, it is quite as well for him to answer them as any one else.

"When caps amongst a crowd are thrown,
Those whom they fit may put them on."

I still persist in all I have asserted, and therefore leave it to your readers to decide against whom the charge of unjust and unmanly' conduct may most truly be brought."

Yours respectfully,

J.T. BEALE.

11, Church-lane, Whitechapel, Nov. 3, 1835.

PRINCIPLES OF RAILWAY LOCOMOTION.

Sir,-Nothing gives me more pleasure than to acknowledge an error, and to rectify it as soon as it is pointed out. Now, although Mr. Anti-Carper does not positively assert that there is an error in my last theorem for ascertaining the velocity on inclined planes, yet he calls upon me to give a demonstration of its accuracy. In proceeding to comply with his request, I discovered that I had made a slip. I asserted that if V is the velocity in miles with which a body is projected down an inclined plane, whose length is S, and perpendicular descent h, the last acquired velocity in miles will be V+

Sir,-Considering slate platforms for railway's will answer, it will be a subject for experiment to determine the requisite thickness. They should be "stronger than strong enough;" but not unnecessarily so. Two-inch slate has been found sufficiently strong for paveinent over which heavy weights have to pass at the London Docks; therefore it is probable that three-inch slate slabs would be sufficient to sustain the loads, and to hold firmly the fastenings for rails. But it would be necessary to make experiments, to ascertain whether the weight of such slabs would be sufficiently great to keep them steady; the rails being fixed to the platform itself as

proposed, would, however, tend greatly to increase the stability of both. Besides, if the slate slabs are laid in concrete, they may be fixed thereto by means of screws in rough slate blocks embedded in the concrete. In this way, slabs, comparatively light, may be made as steady as heavier ones, depending entirely on their own weight, and the adherence of the concrete. I have stated, that a slate platform something less than five inches thick, would be as heavy as the blocks used near Chalk Farm; but if a less thickness would suffice, the advantage would be the greater.

I have proposed introducing into the platform brass or copper nuts, but per

haps the slate may be tapped to answer that purpose; and it is thought that the thread of the nut or bolt of slate will be found as strong, if not stronger, than the hardest oak. It would require some consideration, and, perhaps, a little experience, to determine the best form of thread, and the best means of drilling and tapping. A reward should be offered for the best plans for these purposes.

I think it possible some improvement may be inade in the form of the rail, but it is not necessary to allude to this at present, as, by any form of parallel rail, the requisite thickness and the utility of a slate platform may be de termined.

I have made particular inquiries (and, from my own knowledge, I can depend on the information I have received), respecting the durability of Kirkby slate, which I consider particularly applicable for railway platforms.

Gate Posts made of this slate, which have been in the ground from time immemorial, have been examined, and do not appear to be at all decayed; but the part out of the ground is rather

harder than that below the surface.

Old Flags, such as you call paving, and also the foundations of old walls, have been examined, and are just in the same state as the gate posts.

Stones (Kirkby slate material) laying across streams, have been remembered in the same situation for the last fifty years, and appear no worse, except a little loss of colour; and slates which the salt or sea water has frequently covered for the last forty years, do not appear at all changed except in colour.

This slate material, where, for roofing, it meets the Welsh in the market, obtains a higher price on account of its strength and durability.

In laying the slate platform, and in fixing the rails, the methods proposed are such as will permit them to be taken up and relaid with the greatest facility, and without waste of material. In the event of embankments settling, or the foundations in any place giving way, it will instantly be seen by the slabs being thrown out of their true positions; and by the facility with which the several parts may be taken up and refixed, any repairs may easily and readily be made. But it appears to me, that a railroad roofed with slate slabs, united by strong

iron nails, would protect the foundation from the weather, and render any changes of much less likely occurrence.

It is only by experiment, the actual cost and value of slate platform railways can be ascertained. It may, however, be stated, that where they are adopted, the rails would be more likely to be kept perfectly parallel, and the bed of concrete would not be required to be so thick as the ballasting of the road at Chalk Farm; consequently, in some places a foot or 18 inches would be saved in the excavation. A much less strength of rail would be sufficient; chairs, spikes, keys, oak plugs, and stone blocks, as at present adopted on the Birmingham line, would not be necessary. The cost of all these would be nearly, if not quite, equal to the concrete slate platform and new rail. But the steadiness of a railway thus constructed, would, I should think, be found in the end to be the cheapest, if even the first cost be more, as it would greatly reduce the wear and tear at present experienced, and which is attributed to the vibration of the rails.

POISONING BY ARSENIC. Sir,-There has no poison been employed for the purpose of destroying human life, to an equal extent, or with deadlier certainty, than arsenic. Ve.. getable poisons discover themselves generally both by colour and taste; laudanum imparting a dusky brown hue to coloured wines, and a dirty greenish hue to liquids generally; and opium, by a disagreeable odour and nauseous taste, is easily distinguished in very small quantities in articles of food. Oxalic acid held in solution is known by its bitter taste, and the mineral salts in the same manner are known by their acidity; but arsenic being tasteless, without any smell, and colourless, is therefore more difficult to detect by the immediate senses, and hence affords the greater facilities for perpetrating the most diabolical crimes through its agency.

Chemists and medical men in England, but more especially in France, have given their attention to devise some