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to notice my paddle-wheel generally, and perceive the force of your objection respecting weight, but this is true only when the fixed frames are attached to the wheel, which are not necessary and without them my wheel is as light as any improved paddle-wheel, and lighter than

most.

An advantage would certainly be gained by adopting your suggestion of rods instead of plates for the vertical paddleframe bars, in the circumstances to which you refer; but in their present form they prevent the lateral escape of water from the paddles when propelling.ne

Your engraver has, by mistake, carried his water-line of fig. 2 to the wheels B and C, which are withinside of the vessel. I am, Sir,

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Your obedient servant, oft as
H. PICKWORTH.EN

1, Lincoln's Inn New-square,
Aug. 15, 1836.

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The Directors have the satisfaction to announce to the Proprietors, that the progress of the works generally, in the last six months, has been such as to warrant the expectation which was held out at the last meeting, that the whole line will be completed by the summer of 1838, and the first 21 miles from London in the spring of 1837.

Of the Primrose Hill Tunnel, which is 1105 yards long, only 114 yards remain to be made; the Kensal Green Tunnel is finished, and traversed by the Company's locomotiveengines; 1423 yards are completed of the Watford Tunnel, the total length of which is 1793 yards; and the difficulties which were presented by the quicksand in the Kilsby Tunnel have already been so far surmounted, as to leave no doubt in the mind of the Company's engineer, that they will not delay the opening of the railway beyond the time mentioned. With reference to the other portions of the work, the Directors are making every exertion to forward them, so as to give the Proprietors the benefit of a revenue at the earliest possible period; satisfied that although for the attainment of this object an additional charge will be incurred by the Company, the advantage to be derived from it will be more than commensurate to the expense.

The Directors have entered into a contract, under the guarantee of two responsible sureties, with Mr. Edward Bury, of Liverpool, an

able and experienced builder of locomotiveengines, for the conveyance of passengers and goods, on the railway, by locomotive-power, too whatever extent may be required, at a fixed rate of remuneration; the Company providing engines of Mr. Bury's specification, and Mr. Bury, on his part, maintaining and keeping them in repair; the contract to be in force for three years from the opening of the railway. The Company have thus ased to themselves the advantage of locomo

at a uniform and moderate rate, and under a system of management which it is the interest of the contractor to render mutually beneficial to the Company and himself. The Directors have also contracted for such locomotive-engines as will be first wanted, and for a portion of the carriages.

The Directors in referring to the Bills for railways, connected with the London and Birmingham, which have received the Royal Assent in the present Session, feel themselves called upon to congratulate the Proprietors on the great accession of traffic which they may anticipate from the direct communication opened with the northern and eastern parts of the kingdom, by means of the Midland Counties, North Midland, and Birmingham and Derby Railways, not to mention the connexion between Birmingham and Gloucester, by the Birmingham and Gloucester Railway, nor minor lines, which will all contribute to swell the revenue of the Company. Acting upon the suggestion of the Proprietors at the last General Meeting, and considering it desirable that a connexion should be secured with Leamington and Warwick, the Directors have instructed the Company's engineer to ascertain the levels for a branchline to those places, to join the London and Birmingham Railway near Coventry; and they have also set on foot the usual investigation into the traffic, so as to be prepared to follow up the object with such measures as may, in the opinion of the Proprietors, be deemed expedient.

By the statement of accounts now to be laid before the Proprietors, it will appear that £. 8. d. The receipts to the 30th June were.. 1,955,608 0 5 The disbursements........ 1,492,100 16 8

That the balance in favour

of the Company was, at
that date...

463,507 3 9

And that the amount received on loan, pursuant to the powers given by the last General Meeting, was 443,800%.

It is estimated that the liabilities of the Company, for the next six months, will be sufficiently met by the cash at their disposal, and by loans which have been tendered and agreed for, with the addition of calls. Great as the present scale of expenditure will ap

pear, the Directors are satisfied that so long as the works proceed with energy proportioned to that expense, the Proprietors will hail the increase as an additional evidence of the approach of their great undertaking to completion.

SUBSTITUTE FOR LIGHTHOUSES ON THE SHORES OF THE BLACK SEA.

Translation of a Note addressed to the British and other Foreign Ambassadors at Constantinople, in December, 1829. By Colonel MACERONI.

From the highest antiquity, the Black Sea has had the melancholy celebrity of being the most dangerous of all those which have been, or are at present, frequented by navigators! Thus it was named by the Romans, "AXENUS" sive inhospitalis. The nature and the direction of the winds which predominate― the formation of its coasts and shallows— of its very ports and its atmospherepresent innumerable dangers, even in summer; in the winter these perils are augmented a hundred-fold! Since the 1st of last November, no less than eleven out of twenty-three vessels, which have sailed between this port and Odessa, have been miserably lost!

By the aid of lighthouses placed on dangerous places, or at the entrances of harbours, the navigation of ships in the vicinity of shores is greatly aided during the darkness of the night. But unless such lights be sufficiently refulgent and elevated, and unless the atmosphere be sufficiently clear to permit of the lights being seen at a sufficient distance, it often happens that the unhappy sailor does not discover them in time to avoid the dan-. gers which they indicate, or to enter the harbour of which they announce the entrance!

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The dangers of the Black Sea are greatly enhanced, and indeed mainly consist, in the dense and sudden fogs which cover its surface. It would be very easy to account for the formation of these fogs by referring to the currents of cold air, which, suddenly rushing from the north-east, meet the warm and moist atmosphere confined within the mountainous margins of the Black Sea. this disquisition is not to my purpose, because no remedy can be offered for an exhibition of the laws of nature depending on geographical features of locality. The fact is, that whenever a north wind

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358

THE ELECTRICAL THEORY OF THE UNIVERSE.

blows, especially in the autumn and in winter, the Black Sea is covered with an almost impenetrable mist. The course of a vessel steering from Odessa to Con- stantinople is from north to south. If a strong wind prevails, and the mouth of the Bosphorus be missed, owing to mist or darkness, the rounding of the southern coast causes the unhappy vessel to find itself almost immediately with a leeshore a-head, upon which it rarely escapes being driven and totally lost!

It is absolutely necessary that the entrance of the Bosphorus should be recognised at a very considerable distance, because if it is overshot, with a strong north wind blowing. perdition is sure to follow. The amount of lives and of property annually lost in this way is truly appalling! Twenty-seven vessels, and their crews, have thus perished since I have resided in this capital! It seems that, when in a gale of wind from the north (always accompanied by a mist) if the entrance of the Bosphorus be once overshot, there is no further hope. The low, shelving southern coasts of the Black Sea offer no other refuge, or none can be discerned.

To the evils above sketched out I propose to apply a palliative. Lighthouses are admirable constructions; but they are expensive, and require time to erect. Moreover, on a low coast it is not easy to give them that degree of elevation which will ensure their being descried at a sufficient distance. Besides which, the case is urgent, and a remedy is called for at this very moment, while we daily and hourly receive the afflicting accounts of loss of life and property to an enormous

amount.

The expedient which I propose is the use of rockets, projected vertically in the air during a storm, from such points as it is essential to designate to the bewildered navigator. A 6-pounder rocket, properly made, will rise above 1000 yards perpendicularly in the air. At that elevation the head or pot is made to burst, and about half a pound of combustible composition, of a most refulgent brightness, is detached from the rocket, and burns suspended in the air for about one minute. This light is far more intense than any of the lamps of the best lighthouses; and its very superior elevation (being thirty times higher) causes it to be perceived at a much greater distance. Moreover, its sudden appearance, and the

manner of its combustion, can never allow of its being mistaken for some fire on a mountain; and the same suddenness strikes more attention than any fixed light whatever. By means of a little parachute, invented by Sir W. Congreve, the cage containing the refulgent light is suspended in the air so as to fall a very few yards during the period of its combustion. I have discovered a composition which gives much more light than any hitherto used.*

Depôts of such rockets should be formed at the necessary points, only to be sent up on the occasion of a storm by night. One may be fired every five or ten minutes; and as the number of stormy nights in the year does not average more than thirty, and that not during the whole night, the consumption of rockets would not be an expense of national importance. When rockets are projected from more points than one, the locality may be indicated by a difference in the colour of the light. Some may give a red, a green, a white, or a blue light. To cover the expense, a small tax or toll might be exacted from all vessels navigating the Bosphorus and the Black Sea; which I suppose they, or their respective Governments, would gladly submit to, in consideration of the great advantage received. I am ready to give directions and exhibit experiments, to prove the merits of my plan, quite gratuitously.

(Signed) MACERONI.

ELECTRICAL THEORY OF THE UNIVERSE.

Sir,-Your correspondent Kinclaven labours under a mistake with regard to the "Electrical Theory of the Universe." It is no where stated to be in accordance with the laws of Kepler, nor, indeed, with any other; it would have been quite premature to have made such a statement. If he will examine it more attentively, he will perceive, that so far from the momentum of the planets being extinguished, they are supposed to be accelerated, because it is assumed that they move in spiral orbits, which (the orbits being elliptic) is the same in effect as if they were rolled down an undulatory inclined plane. This assumption derives support

His Excellency General Count Guilleminot, the French Ambassador here, has seen me set fire to and consume a cypress tree with one of my compound naval rockets, at 1000 yards distance, horizontal range.

from several considerations, as well as from the established fact of the moon's secular acceleration. Kinclaven says, hundreds of reasons might be urged against the electrical theory. This was to be expected; it is in the nature of things that it should be so. The plainest truths in science have been at one time or other opposed by hundreds of objectors: indeed, some weighty objections have been urged against the theory of universal gravitation, which, it appears, have not yet been answered in a manner to satisfy the objectors. The whole doctrine may be said to rest upon the following propositions:-1st. That a body in motion will continue to move uniformly forward in right line, if not disturbed by the action of some external cause. 2nd. That there is no external resistance, that is, that the planets move in vacuo. 3rd. That by the sun's attraction (acting against the momentum), the planet is held or drawn back, and retained in her orbit. Now will this bear a close examination, that the momentum of a body, a quantity subject to diminution and utter extinction, shall remain for ever the same with a constant unalterable force acting against it; by the momentum or diminishable quantity the moving body continually endeavours to fly off from the centre, and by the action of gravity, an undiminishable quantity, the moving body is continually drawn back towards the centre, and yet the momentum, with a constant force acting against it, remains, and is to remain undiminished to the end of time. This is past all human comprehension. Sir Isaac Newton seems to have felt the force of this objection, and a few others, which were urged during his lifetime; in answer to which he put forth the following definition :-" Attraction is an indefinite principle, not implying a particular manner nor physical cause of action, but only a tendency of approaching; whether it proceed from any external cause, or be inherent in bodies themselves, excluding the idea of impulse from its consideration."

Whoever allows himself to reflect upon the above definition, will probably be come cautious and circumspect, and less dogmatical in his manner of asserting the" unerring laws of universal gravitation."

I remain, Sir, yours obediently,
T. S. MACKINTOSH.

ELECTRICAL THEORY OF THE UNIVERSE. --URSA MAJOR'S REPLY TO KINCLAVEN.

Sir, Kinclaven seems to think that discretion is the better part of valour. He was requested to explain the paradox of the tides, but seeing that it might be rather difficult to maintain the position which it would be necessary to take, he shifts his position, and, in answer to Ursa Major, opens an attack upon a point which Ursa Major has no inclination to defend. However, I suppose we shall be enabled to dispense with Kinclaven's demonstration, as I perceive another correspondent has taken the field armed with a machine, by the help of which he proposes to give ocular demonstration," that the double diurnal tide is in perfect accordance with the theory of universal gravitation. I congratulate Kinclaven upon the very efficient assistance that he is likely to receive from this able auxiliary with his new theory of the tides, which is about 200 years old. Before Mr. Clarke commences operation with the machine, it might be worth his while to consider more attentively the nature of the demonstrations that are likely to result from its action. What would the machine demonstrate ? Simply this; that one tide is an effect of gravitation, and the other an effect not of gravitation, but of motion, produced by the earth revolving upon an eccentric axis. The absurdities to which this supposition would lead, are, if possible, worse than those that are intended to be removed. Mr. Clarke places the common centre of gravity of the earth and moon somewhere about 200 miles beneath the surface of the former, whilst Dr. Wilkinson finds that it is 2000 miles above the surface; but I suppose a thousand miles or two one way or other makes very little difference.

I beg to thank Kinclaven for his advice, with regard to Professor Airy's work, and to assure him that I am sufficiently read in mathematical science to discern that where there are half a dozen different demonstrations contradicting each other, they cannot be all true. I have subjoined an extract from Dr. Wilkinson, which appears to me to set the matter in dispute in a fair point of view.

I remain, Sir, yours, &c.
URSA MAJOR.

"Kepler, who first suggested the influence of a gravitating principle in nature, with

360

THE ELECTRICAL THEORY OF THE UNIVERSE.

respect to the cause of the tides, entertained an extravagant supposition of the earth being a living animal, and the flux and reflux of the sea the results of the action of respiration. Galileo supposed tides to be produced by the different velocities of the annual and diurnal motions of the earth; if so, the tides should occur at the same periods, without variation in their rise; but they are observed to move through the twenty-four hours, and vary daily in their elevation. The illus. trious Newton, in his Principia, has stated his opinion that there is an attractive power existing between all bodies in proportion to their quantity of matter, and the inverse duplicate ratio of their distance, and hence has reduced to geometrical demonstration the varied influence of the moon as she moves in her orbit, how the tides are governed by her nearest and most remote distance from the earth, the changes observed from the different inclinations of her orbit to the ecliptic, and from the irregular motion of her nodes. Whether such a force or power be hypothetical or real, I presume that the geometrical demonstration will not be affected. If gravitation be not admitted as a principle competent to explain the phenomena, we must substitute some other agent capable of producing all the effects observed.

66 Supposing the mean distance of the moon from the earth to be sixty times the radius of the earth, and if the law of gravitation be assumed, according to Newton, as diminishing as the square of the distance increases, it will be evident that sixty multiplied by sixty, being equal to 3600, will express this proportion, viz. that 3600 lbs. on the surface of the earth, removed to the moon's surface, would only weigh one pound. As the waters of the ocean are the only part of our planet susceptible of any change from such an influence, the tendency of the waters of the ocean towards the centre of the earth will be in the same proportion diminished. Let us suppose the gravitating powers of the waters of the ocean, when under the direct influence of the moor, to be diminished in this proportion, viz. one-sixteen hundredth part. From the law of pressure, with re spect to liquids, the action is equal in every direction, and which action is attributed by Newton to the power of gravitation being uniform; if this power be disturbed in any part, there will be a determination of water to that part, till the equilibrium be restored; and the elevation of waters in that part will constitute the tide. Let us suppose the mean depth of the ocean four miles, thus one-sixteen hundredth part of this being elevated will be about six feet. Newton does not confine the diminution of gravitation in the water of the ocean merely to the influence of that luminary; he supposes a co-operation of the sun, which he concludes, from its quan

tity of matter compensating for its greater distance, produces an effect about one-third of that of the moon; so that when combined, as in new moon, their united effects would under such circumstances produce an elevation of eight feet. When the moon is in her quadratures, i. e. when she appears to us as a half moon, then they counteract each other, and the tide will be proportionate to the difference, viz. by the above supposition, four feet, constituting what is denominated Neap Tides.

"These admeasurements are only assumed for the purpose of illustration. It is well known that at the same period there is a spring tide at new moon, at the Nadir, as well as at the Zenith, part of the earth; this presents the greatest difficulty to the Newtonian theory. If, according to the Newtonian hypothesis, an elevation of those waters, which are in a direct line with the moon at or near her meridian, is to be referred to the cause afore mentioned, the same hypothesis is extended to account for the tides on the opposite side of the globe, to the earth itself being attracted from the waters situated at the Nadir. If we consider the elevation of the waters on each side of the globe to be eight feet, it is evident that the earth must, by the attractive power of the luminaries, have been removed sixteen feet. However incomprehensible this theory is, the difficulties are increased by the application of the same principle to the explanation of spring tides at full moon, when the earth is placed exactly in a line between the two luminaries.

"In the year 1779, I published an 'Analysis of a Course of Lecture.' I therein attempted to explain the phenomena of the tides, on the principle of the motion of the earth round the centre of gravity of the earth and moon. A similar explanation had been surmised by the learned Dr. Wallis in 1666. I am not aware that he attempted any demonstrations of such an opinion. In the different courses of lectures I have delivered during a period of near thirty years, when upon the subject connected with the tides, I have invariably attributed them to the result of this motion. The earth does not move in a regular elliptic orbit round the sun, but describes a series of volutes round the centre of gravity between the earth and the moon. As the density of the moon is to the density of the earth as 11 to 9, which has been deduced from calculations of the space the moon falls below the tangent of her orbit in a given time; as the diameter of the moon is 2161 miles, therefore is in proportion to the mass of earth as 1 to 49-22, from these data it is evident that the distance of the moon's centre from the common centre of gravity of the earth and moon is as 39.788 to 1, or 5880 miles from the centre of the earth.

"It will hence appear that the earth has

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