coating, or coatings of the varnish, upon one side only of one of the fabrics or substances, applying the other fabric or substance uncoated upon the clammy viscous surface of that which has received one or more coatings of the varnish, and then complete the process as before suggested." The substance of all this is, put on the cement with a brush, sometimes on one cloth, sometimes on both; these are put together, and pressed together, with a certain degree of heat. But I would call your attention to the description of the solution which is to be used, in connexion with another part of the specification which applies still closer to that part of the invention. "Now, whereas caoutchouc, in a state of solution, and dissolved in manner hereinbefore described, is well known to chemists and others, and not new, therefore I do not claim any right, title, or privilege, in respect of the same; but a manufacture of two or more pieces of linen, woollen, cotton, silk, leather, or paper, or other the like substance, any or either, or any combination of any or either the same, cemented together by means of flexible cement in manner hereinbefore described."-Mr. Macintosh says, I claim the produce of certain results-the union of two fabrics together by a cement, rendering it impervious to air and water; there are various modes of doing it; I will tell you one: he disclaims being the inventor of the solution; he only tells you the mode he has found the best; it is by a solution of Indiarubber; but does he confine his invention to the cement by means of that solution? I submit he does not. I ask you if a man shall find any other solution, or had found any other flexible cement, by which he had united two fabrics together, and rendered them impervious to air and water; I ask whether Mr. Macintosh would not have had a much stronger argument to come forward, and say, my claim was expressed in the most distinct terms-the union of two fabrics by any flexible cement; you are unjust, you are applying critical acumen, you are improperly depriving me of the benefit of my patent, because I give you one species of cement which will accomplish it, and you seek to limit me to that one, though I told you it was not the only one, but the one which, according to my experience, I found the best? But to-day he cuts down his specification to the particular instance which is given as the best, and says-by flexible cement I do not mean any flexible cement, but only Indiarubber. As far as my intellect goes, I cannot entertain a doubt but that this was intended to apply to any flexible cement; at least, it is very ambiguous; at least it would have been open to Mr. Macintosh to have contended with an equal chance of success

the one way as the other, and I shall therefore pray my Lords' judgment; first, whether this is not a claim to the extent which I have mentioned in the specification; and next, whether at least it is not so ambiguous and doubtful, so disingenuous in the mode of doing it, so uncertain in what he claims, as to be void. That is my first objection. Mr. Macintosh has claimed more than he is entitled to; he has claimed for all flexible cement, and he now shrinks from that because he knows he cannot sustain his patent to that extent; but his specification is against him in this; and if it is ambiguous and doubtful, it is equally objectionable. My next applies to Mr. Macintosh's conduct, in regard to the solution. He brings forward scientific witnesses upon this point-and I will say a few words on the value of scientific evidence. There was an action brought on a policy of insurance, and the question was, whether a sugarbaker who had altered his mode of boiling sugar, by boiling it with oil instead of steam, had adopted a more dangerous mode than that which he used at the time of the insurance, because if he had, the insurance was void. Sixteen witnesses for the plaintiff swore all their experiments proved decisively that the boiling by oil was less dangerous than boiling by steam; sixteen witnesses for the defendant were perfectly satisfied, and their experiments proved their accuracy, that the boiling by oil was much more dangerous than steam; on which my Lord Chief Justice Dallas said, "A melancholy day this for science and scientifie men.' Another unfortunate instance we have in the case of Eliza Fenning, against whom the scientific men gave evidence that arsenic in pudding would turn a knife black, and it was upon that evidence she was found guilty; it turned out that it would not do it, but that an onion would!

(To be continued.)

TAIT'S GASOMETER.

Sir, I perceive that your correspondent "Clovis," repudiates his identity with Mr. Stephen Hutchison. Why then continue to wear a mask ?-there may be occasions on which a mask may be allowed; but this, most assuredly, is not one of them. Assertions have been made as to the failure of my gasometer, by "the unskilful and unscientific application of the hydraulic-joint," which I have impugned as being untrue in point of fact. An opportunity has been offered (in Mech. Mag., No. 655, p. 443,) to your correspondent, to adduce his justification and authority for making such assertions. He has, however, allowed the

opportunity, thus offered to him, to pass; and, instead of attempting to adduce any authority, he has repeated his calum

nies.

"Let me know" (he says)," the time and place, when and where your gasometer may have been, or is still to be, seen in actual operation:"-" Give me ocular proof, and then I will tell you when and where your gasometers failed!" Now, all this I call exceedingly modest; your readers must be struck with its propriety. He does not know when and where my gasometers were erected; but he will feel obliged to me to let him know! -and having obtained this very necessary preliminary intelligence, he will then, no doubt, be in a condition (but not till then) to afford me the information required in my letter in Mech. Mag. for 27th Feb. p. 443, as to the "time, circumstance, and place," where my had been abundantly tried;" gasometers but that owing to my "unskilful and unscientific application of the hydraulicjoint, I had the pain of witnessing their complete failure!"

66

This is positively too ridiculous. I have neither inclination nor time to Occupy with such a Homo. The only favour I should ask of him is, that he will not do me the injury to praise me. I have just another remark to make, and then I have done with him.-In your Magazine for 20th of Feb. last, p. 413, he refers to a gasometer at Leeds, as an instance of the failure of my gasometer. This turns out to have been rather an unfortunate assertion of your correspondent "Clovis:" seeing that at the very time when he referred to this gasometer, as mine, he was fully aware (see Mechanics' Magazine of 5th March, p. 455), that it was both designed and erected by Mr. Hurst! I cannot, after all this, condescend to notice any further effusions of Clovis's. I am, Sir, &c.

March 8, 1836.

W. TAIT.

NOTES AND NOTICES. Preservation of Animal Matter.-At a late meet. ing of the Asiatic Society, a human hand, and a piece of beef, preserved by means of a preparation of vegetable tar, found on the borders of the Red Sea, in the vicinity of Mocha, and a specimen of the tar, were presented by Lieutenant-Colonel Bagnold. In an accompanying letter Colonel Bagnold observed-" During my residence as Poli

tical Agent on the Red Sea, a conversation with some Bedouin Arabs, in the vicinity of Mocha, led me to suspect that the principal ingredient used by the ancient Egyptians in the formation of mummies was nothing more than the vegetable tar of those countries, called by the Arabs katruan. My first trials were on fowls and legs of mutton, and which, though in the month of July, and the thermometer ranging 94° in the shade, succeeded so much to my satisfaction, that I forwarded some to England; and have now the pleasure to send, for the Society's information and inspection, a human hand, prepared four years ago by my brother, Captain Tho mas Bagnold. The best-informed among the native Arabs think that large quantities of camphor, myrrh, aloes, and frankincense, were used; these specimens will, however, prove that such were by no means necessary, as the tar, when applied alone, penetrates and discolours the bone. The tar is obtained from the branches of a small tree, or shrub, exposed to a considerable degree of heat, and found in most parts of Syria and Arabia Felix."-Athenæum.

Adhesion on Railways.-At a meeting of the Istitution of Civil Engineers (reported in the Athenæum) it was stated that a great increase in the power of the engines in drawing loads after them arose from the use of wrought-iron rails, and wheels, hooped with wrought-iron, instead of cast. The Planet engine was instanced, weighing 74 tons, and drawing 150 tons. The proportion of ordinary weight between the engine and the load might be called 1 to 7, though 1 to 11 was a fair representation of the power of traction as a maximum in favourable weather on a level. Casehardened iron had been proposed for the rails, but had been abandoned in consequence of the chills, which answered perfectly at first, losing their effect by the repetition of the process, so that the casehardening was not equably effected.

Cast and Wrought Iron Wheels.-It was also state, that where cast-iron wheels on railways wou'd only last six or eight months, wrought-iron would serve at the same work three or four years.

The Wear of the Rails of the Manchester and Liverpool line was stated to be 1 120th of an inch in depth per annum. The flanges rarely come into contact with the rails; one of the oldest wheels being taken off a carriage, the marks of the turningtool was found on the flange.

New Application of Caoutchouc.-India-rubber has been applied in Paris to the casing of steel busks for ladies' stays, and is said to answer well in resisting the metallic oxides upon the dresses.

French Academy Prize. The great physical prize proposed by the French Academy of Sciences for 1837, is to be, for the determination, by anatomical and physical researches, what is the mechanism by what the sounds in the voice of man, and vertebrated and invertebrated animals, are produced.

Patents taken out with economy and despatch; Specifications, Disclaimers, and Amend. ments, prepared or revised; Caveats entered; and generally every Branch of Patent Business promptly transacted. Drawings of Machinery also executed by skilful assistants, on the shortest notice.

LONDON: Published by J. CUNNINGHAM, at the Mechanics' Magazine Office, No. 6, Peterborough-court, between 135 and 136, Fleet-street. Agent for the American Edition, Mr. O. RICH, 12, Red Lion square. Sold by G. G. BENNIS, 55, Rue Neuve, Saint Augustin, Paris. CUNNINGHAM and SALMON, Printers, Fleet-street.

SHEER-MASTS.

Sir,-In requesting the favour of the insertion in your Magazine of my plan for masting ships of the line with sheermasts instead of those now in use, I am aware that those persons who have been in the habit of viewing the present system of masting and rigging ships, as approaching to perfection, will hardly think it worthy of attention; however, as all things must have a beginning, I venture to propose this great innovation, with the hope, that among the British and foreign naval officers, and dock-yard engineers, who may have access to your pages, it may possibly find some supporters who may deem it worth some experiments, which will either condemn it to oblivion or render its adoption advisable.

The experiments which I have made for testing my plan have been only upon a small scale, and will not, therefore, be considered conclusive. The respective masts were of equal weight, height, spread, and quality of wood, and the result was obtained by placing them in a horizontal position, and then suspending weights to them until they broke. The sheer-masts proved to be nearly onethird stronger than the others. Their superior strength may be reasonably accounted for by simply stating, that the whole of their fibres are in constant requisition for their support; whereas under present circumstances the lee rigging of a ship is not only of no assistance in supporting the mast and weather rigging, but actually distresses them by the amount of its weight. Whether the difference of strength be as double the weight of the lee rigging deducted from that of the entire mast and rigging, I will not pretend to determine; it may, however, possibly approximate to this.

Properly to test the strength of sheermasts, I should recommend an experiment on a scale of not less in length than th of a first-rate's main-mast, viz. about 15 feet; or 4th the length, or about 30 feet, would be still better.

Now, supposing these experiments to be made with as favourable a result as I have obtained, the subject would assuredly be worthy of further consideration; and other good qualities might be discovered-amongst others, a great saving in the naval estimates.

I shall now proceed to point out my

own views of the sheer-mast's good qualities as well as defects.

1st, and most important.-Its superior relative strength.

2dly. Its tendency, upon the principle of diagonal braces, to strengthen a vessel's hull instead of weakening it, as does the present mast and rigging-For instance, the main-mast of a first-rate ship of war, with all its other masts, yards, rigging, sails, &c., weighs little short of 50 tons, which weight, together with the force of the tension of the rigging (the amount of which, I believe, has never been calculated) rests upon a small bearing of the keelson, upon which the mast is stepped, pushing it downwards, whilst the rigging is pulling the ship's sides upwards Now, in a sheer-mast, supposing it to consist of five sheers, as shown in the engraving, the weight upon each bearing of the sheers would be only 10 tons. To exemplify how completely sheers perform the functions of diagonal braces, it is only necessary to get too weak planks of the proportional relative breadth and length of a ship, and rigged on the respective plans, when it will be found that the plank with the sheers will be prodigiously strengthened, whilst the other will be much warped, if not split, by the opposing strains of the masts and rigging. Again, the weather side of the latter, under a press of canvas, has to support the greater part of the strain, and the lee side none whatever; whereas in a sheermasted rigged ship, the weather side would be relieved from half the strain, and the lee sheers would act as shores to the upward buoyant pressure of the lee side.

3dly. Supposing the relative strength of sheer-masts to be so considerable as to bear a less extension of base, 1 should, consequently, place them inside the ship's hull, and abut them to the shelve-piece on the lower-gun deck; or if higher (for convenience) I should properly strengthen the hull to receive them, in which case all the channels might be dispensed with, making the ship much snugger, and certainly adding to her sailing qualities when close hauled, besides clearing her batteries.

4thly. Greater stowage in the hold, which would be disencumbered of ponderous masts-excepting the main-stay sheer-mast, as proposed in the present plan.

5thly. A great reduction of labour, time, and expense, in fitting ships out; as all the ships in ordinary would be absolutely rigged, as far as their lower masts were concerned-a point of great importance to a great Naval Power. This would include also a saving in the expense of the standing rigging-room in the storehouses of his Majesty's dockyards, and the employment of so many riggers.

6thly.-A sheer-masted ship could be more easily hove down, because weights and purchases might be more generally applied to sheer-masts without danger of carrying them away.

The above important qualities will well bear the placing in the opposite scale a few apparent defects, the greatest of which appears to be, the exposure to shot when in action, which is the reason I recommend a pyramidal sheer-mast to be composed of five sheers, for, independent of the effect of shot, I should only use three of them, as being the strongest mode of construction, the weights of the respective pyramidal masts being equal; with five sheers, three of them would support each other, in case two were shot away, so that probably a mast composed of five or six would stand as good a chance in action as the present single mast. This point, however, requires experience; and if spare sheer-masts would not be too cumbrous to take to sea, there would be much greater facility in repairing the masts after an action than at present.

It will be seen by the engraving, that the sheers are united at their upper end to a conical cap, forming the apex of the pyramidal mast, through which is placed. the top-mast, with its heel properly secured by cross-pieces (as trusle-trees) united to the sheers.

The mode of combining the heads of the sheers to the cap in the strongest and most efficient manner, as also that of fixing the heels to the vessel's hull, might well form a subject for a patent; and, indeed, many inventions would arise out of the system, if its adoption should ever be contemplated.

As for the principle of sheer-masts, it has no originality whatever, having for ages past been adopted by the Chinese; many patents have also been taken out for them, the most modern by Mr. Guppy, Mr. Higgins, and Lieutenant

Molyneux Thuldham; and if these gentlemen would have the goodness to state, in the pages of your Magazine, the result of their experience, it would throw additional light upon the subject, and possibly call the attention of the naval authorities to it, who, in consequence of the vast saving of naval expenditure which would accrue if the system could be adopted, might think it worth while to order an experiment to be tried at the mast-house of one of his Majesty's dockyards, which could be done at a trifling expense, in the manner in which I have already pointed out.

Supposing the present dimensions of our largest ships to be doubled, I cannot see how the difficulty of masting and rigging them could be got over, unless by the adoption of a pyramidical structure of sheer-masts of some kind or other, with the further addi. tion of various kinds of braces to strengthen them. I have, therefore, shown in the engraving, sheer-masts to a first-rate ship of war, to illustrate my opinion, that the larger the ship, the greater the necessity of resorting to pyramidical sheer-masts. Whether smaller vessels should be fitted with them when the absolute necessity does not exist, may perhaps be questionable, but, generally speaking, the strongest principle is the best on any scale.

One argument in favour of the presen system of rigging is, that the play of the masts and elasticity of the shrouds form the vessel's sailing qualities; and I know that many proofs could be given of that tendency by captains in the navy. Now, sheer-masts can have but a trifling degree of elasticity; but, then, for this as an objection to be borne out, it must be proved, on the other hand, that all vessels which have been hitherto rigged with them have been, consequently, bad sailersIf this cannot be established, and even the contrary be proved, the loss of play and elasticity will go for nothing.

The tendency sheers have of throwing out the ship's sides need hardly be mentioned, because it cannot be so very considerable as not to be easily restrained by proper modes of strengthening and fastening the hull; if, as I have heard, a ship's sides have opened by the lateral pressure of sheer-masts, it must have been entirely owing to want of discrimination, in not adapting the parts of the. ship to the