cation of the steam-engine to the propulsion of vessels; who made the designs for, and superintended, the construction and launching of the first steam-boat ever built in Britain. We allude to the Miller steam-boat, which was tried successfully on the Caledonian Canal as early as 1789, and which being afterwards laid up at Bruce Haven (near the Carron Works), was seen there by Mr. Fulton, the celebrated American engineer, and copied with such success on his return home, that he was enabled to transfer to his country the honour of taking the lead in this interesting field of improvement. We have now to introduce Mr. Taylor to the notice of the public, as the author of an improvement which may probably turn out to be of even greater consequence than the invention of steamboats. It consists in the substitution of mercury for steam, as the source of a motive power. Many experiments have been made with this view by other individuals-for example, by Dr. Stirling, of Kilmarnock, Captain Pottinger, of Carrickfergus, and Mr. Job Rider, of Belfast-the last of whom is said to have had a clock which was kept in motion by the aid of mercury alone. Nobody, however, appears to have succeeded to the extent which Mr. Taylor did. He had a boat which was actually propelled by means of mercury. The way in which other experimenters have sought to accomplish this great desideratum, has invariably been, either to heat and cool the mercury suddenly, so as to gain a vacuum by the alternate contraction and expansion; or by a contrivance like a waterwheel, resting on its axis at an angle of 90 degrees the said axis being formed like the Archimedean water-screw, to make the mercury that descends by the buckets return back through the spiral grooves of the axle. Mr. Taylor pursued a different method. He had a horizontal wind-mill placed on the deck of the boat, by means of which he worked alternately two columns of mercury against the atmosphere; and in this way obtained a power that acted as effectually and regularly as steam itself. Mr. Taylor's model-boat and drawings are understood to be in possession of his family; and it is to be hoped they will not allow any

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feeling of resentment they may entertain (not unjustly, we allow), on account of the little regard which has been paid to his past claims on the grateful remembrance of his country, to prevent them from laying a more particular description of them before the public. We live in times now, when, in consequence of the greater publicity given to all useful inventions, and of the greater interest taken in them by the people at large, men of genius are much surer than heretofore of reaping the harvest of their labours.

F. L. S.

SOLUTIONS OF G. S.'s MATHEMATICAL PROPOSITIONS, No. 300. (Continued from last Number, p. 316.)

Proposition Second.

Theorem.-" Let there be two concentric semicircles; and from any point in the circumference of the greater let two tangents be drawn to the lesser. Then shall the locus of the point of intersection of the two lines drawn from the extremities of the diameter of the interior semicircle to the opposite points of contact be a circle given in position and magnitude."

BY MR. THOMAS HUGHES,

Pupil, Mansion - house Academy,.
Hammersmith,

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ever point of the circumference B may be; for the same reason, BF and the angle HBF will be constant quantities,

the whole angle EBF is invariable, and EB and BF being invariable, EF is constant, .. the arc ESF is invariable; .. the arcs FG+ ED are constant, but the angle FOG is measured by half the sum of the arcs FGED,.. the angle FOG, and consequently the angle DOG, is invariable; therefore, if a circle be described on the given line DG containing an angle equal to DOG, it will be the locus required, and therefore given in position and magnitude. -Q. E. D.

[We have received two or three other solutions of this proposition; but none so accurate as the preceding. Solutions of Proposition Third in our next. — ED.]

SHORT ARITHMETICAL

PROCESSES.

Sir,-If the following rules, which are not generally known, or at least adopted, although they are of great utility in many cases which come under their regulation, should meet your approbation, your insertion of them in your valuable Magazine will oblige your occasional correspondent; and probably they may be of some service to others among your very numerous readers, who may have occasion to adopt them, in contracting sometimes tedious operations in multiplication and division. I shall pass over those that are in every common book of arithmetic, and give only those that are seldom met with.

Case First. If the multiplier be 5, which is the half of 10, we may annex a cipher and divide by 2. If it be 25, we may annex two ciphers and divide by 4; as the multiplicand with two ciphers annexed is the product of 100, so 25 is the of 100 and so on.See operation.

Products by the common methods.
Mult. 4532
Mult. 5374

Case Second.—To multiply by 9, 99, or any number of 9's, annex as many ciphers to the multiplicand as there are 9's in the multiplier, and subtract the given multiplicand from the same; the remainder will be the

product required. In like manner, if

any other figure be in the unit's place, the process is the same; by multiplying the given multiplicand by the number that that figure wants of 10, and subtracting this product from the given multiplicand the remainder is the product sought.

25

26870 10748

134350

Case Fourth. The product of any number of repetends, as 22, 222, 33, 333, &c. may be found without taking down all the products, by taking the product of one of them, and making the addition from that product as if all the products had been taken down. In this manner, begin at the right hand, and take the first figure first, then the first and second; and supposing we have three figures in the multiplier, we then take the first, second, and third, and add them together, then leave the first, take the second, third, and fourth; always taking care to keep as many figures as there are figures in the multiplier.

Case Fifth.-The work of multiplication may be often abridged and rendered more easy, thus: In multiplying by 93 or 39, first multiply by 3 and the product of that by 3 again, care being taken to place these products properly before adding them: sometimes the products of more than one figure may be obtained in this manner from the product of a figure already found, as 832 or 328, first by 8 and then by 4; all the care in this is the setting of the product.

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columns will fix them better in their minds; and, indeed, if there is any thing in them of any service, you may thank them for them and not

A GAEL.

THE THAMES TUNNEL. "Where sheep had used to browse and cattle fed, The wondering waters new dominion spread; Where rows of houses stood in many a street, Now, rows of ships present a city fleet: Nay, we had made, had Nature not refused---Had Father Thames not begged to be excusedA pretty Tunnel underneath his bed, And left him running grumbling over-head; Had scratch'd a track out, like a grubbing mole, Thro' a long, dark, and damp, and dirty hole; Like rats in sewers, had flounder'd thro' the mud, Instead of sailing, duck-like, o'er the flood: But bubbling springs choked up the project deep, And trickling waters o'er our folly weep."

The Age of Frivolity; a Poem published in 1806. So sung the satirist of 1806, on the failure of Mr. Dodd's attempt to penetrate under the Thames at Gravesend; and so he would probably have had occasion to sing again over the more recent failure of Mr. Brunel, but for the proceedings of that general meeting of the Thames Tunnel proprietors which we announced in our last Number was to take place this week. The proprietors, we are happy to say, have passed a resolution which will have the effect of taking the further superintendence of the work out of Mr. Brunel's hands; and now there can be little doubt of its successful completion. The directors reported to the meeting, that the plan of Mr. Brunel had been found to be attended with an expense 66 apparently incompatible with the reasonable expectations of the shareholders to derive even a moderate remuneration for their advances;" and their chairman, Wm. Smith, Esq. M.P. confirmed what we stated some weeks ago, that Mr. Vignolles is prepared to give securities to complete the Tunnel at something less than half the expense which had been estimated as the probable cost of it by Mr. Brunel. The partisans of Mr. Brunel endeavoured to counteract the strong impression which these facts made on the meeting, by contending that as Mr. Brunel had been the person to prove the practicability of making the Tunnel, by carrying it to the extent of 600 feet, he ought to be the person employed to complete it, no matter at what expense to the proprietors or to the country. Mr. Wm. Smith, Jun. (whose speech on the occasion is particularly deserving of praise for the spirit and ability by which it was distinguished) denied that the company were under any such

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obligation of gratitude to Mr. Brunel as should induce them to sacrifice their own interests to his; and entered into a variety of details to shew that the excess in his expenditure, beyond the amount of his estimates, was not owing (as had been pretended) to unforeseen circumstances, but to sheer extravagance. The Marquess of Salisbury, Admiral Sir E. Codrington, and Mr. J. Martin, also spoke strongly on the same side; and a resolution, empowering the directors to displace Mr. Brunel, and contract with any other parties for the completion of the Tunnel, on such terms as they shall think proper, was finally carried by a large majority.

A proprietor having inquired whether there was any drawing or model of Mr. Vignolles' plan in the room for inspection, the chairman answered, that Mr. V, had declined exhibiting the details of his plan until the board of directors were empowered to treat with him; but that a model and drawings of the plan had been shewn to several gentlemen by Mr. V. at his office in Furnival's Inn. Mr. Bramah said, that he was one of those who had inspected them, and that they had left no doubt on his mind of the perfect practicability of the mode of excavation Mr. V. intended to pursue.

APPLICATION OF WATER POWER. Sir, The steam-engine is now used so extensively in this country, that water power seems to be in some danger of becoming a drug. I am interested for a gentleman who has two watermills within a short distance of each other; and in consequence of one of the water-wheels having failed, he is at present erecting an iron wheel, from the enlarged dimensions of which he will have about twenty-horse power to sparé, which he is at a loss how to apply. Now, as the "Mechanics' Magazine" is a publication universally read by those who are, or wish to be, well informed on mechanical subjects, I shall be much obliged if you will insert this inquiry, hoping it may meet the eye of some of your ingenious readers, who may suggest some eligible occupation for the surplus power. Should an advantageous, em ployment of the mill be proposed and adopted, a handsome remuneration will be presented to the projector of it. Letters addressed, within the ensuing three weeks, to Mr. George Bush, for S. R., Fordingbridge, Hants, will meet with due attention,

I am, Sir, yours, &e.

A COMMERCIAL MECHANIC

June 30, 1829,

MISCELLANEOUS NOTICES

Mexican Mode of Amalgamation.-The separation of the mercury from the silver is here a clumsy and comparatively an expensive process. Instead of using an iron retort with two parts, like an alembic, placed upon the common open French furnace, the antique per accensum method is the one resorted to. The amalgam is placed under a large bell of copper, which is encased for each operation with unburnt bricks, but so as to leave a space sufficiently great for the quantity of charcoal requisite to produce the heat required. The heat being lateral, the mercury rises towards the top, collects in globules, and falls through a funnel and tube, placed at the bottom of the bell, into a vessel of water beneath the whole; or the whole bell is filled with the vapour of mercury, which is condensed at the lower part. The furnace has a fanciful appearance, like the tombs of the middle ages; the bell being on the top and centre of a quadrangle of masonry, at the corners of which are four pillars of the same, supporting a pyramid, which serves as the dome of the furnace.

f

Large Paper.-Much has been recently said about the immense sheets of printed paper produced by certain Newspaper establishments; but it ought to be known, that the difficulty does not consist in manufacturing paper of almost any size, but in having printing presses of the requísite magnitude. At White Hall Mill, in Derbyshire, a sheet of paper was lately manufactured which measured 13,800 feet in length, four feet in width, and would cover an acre and a half of ground!

Saving in Fuel. It is stated in the Glasgow Chronicle, that Mr. J. B. Nelson, of the Glasgow Gas Works, has discovered, that when air is first heated before being discharged from a pair of bellows, or any other blowing apparatus, it greatly promotes combustion in fires and furnaces. We think this must be a matter of course; but we should not suppose there could be much, if any, saving effected by the process. There must be fuel consumed to heat the air in the first instance, and this will probably be found to balance very nearly the extra power conferred on the furnace,

Substitute for Quinine.-An alkaline substance, somewhat analogous to quinine, has recently been discovered in the cornus florida, and denominated cornine. It has been used with unequivocal success in the case of intermittent fevers, in the same doses as quinine; and the only cir cumstance which precludes its competition with that substance is, the extremely small portion of cornine yielded by the cornus florida.

Hydraulic Lime.-M. Ollivier has succeeded in preparing lime which can be preserved for a great length of time in sacks without losing any of its properties. It is sold in very fine powder; and having been sifted, is free from vitreous particles. From a million to a million and a half of sacks are sold annually, being principally employed in the construction of canals in Bretagne.

INTERIM NOTICES.

All future Communications for the Editor are particularly requested to be addressed to the Mechanics' Magazine Office, 115, Fleet Street.

We have received Mr. Ibbetson's reply to Mr. Child, and shall give the first part of it next week. There is an editorial postscript to the solution of G. S.'s second proposition in our present No., which, it is proper to observe, does not apply to two additional solutions which we have received in the course of the present week.

Communications received from Mr. SquireMr. Baverstock-D.C.-Mr. Richardson G. S.-Mr. Harrison-Mr. Saddington-Mr. Dickenson-Z. A.--Suffolkiensis-A Cambridgeshire Yeoman.

Published, for the Proprietor, by M. SALMON, at the "Mechanics' Magazine" Office, No. 115, *Fleet Street, where Communications for the Editor (post-paid) are requested to be addressed.

J. MOYES, Took's Court, Chancery Lane.

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