**

accumulation of atmosphere at the equator, which under the influence of the same force will gradually decline towards the poles. And a certain consequence of the accumulation will be an increased density at the equator, which likewise will gradually diminish with the accumulation from thence towards the poles. The distribution of the atmosphere results from the order of nature. And that such an atmospherical accumulation and density at the earth's equator do exist, is proved by the fact, that within the tropics, the barometer does not descend more than half as much for every two hundred feet of elevation as it does beyond the tropics. The retardation of the pendulum and the decrease in the intensity of gravity in the equatorial regions, are also attributable to the increased density of the atmosphere in those regions, and not to the earth's centrifugal action or to any dimunition of density. Bodies fall or move with more facility and speed in vacuo than in air, because all resistance to the moving body is removed; through air, than through water, because the air offers less resistance than the water: and it follows as a necessary consequence, that they move with greater facility and speed in rarified than in dense air; and that the resistance to the motion of bodies increases with the density of the atmosphere in which they move. I refer, therefore, to the equatorial retardation of the pendulum and decrease in the intensity of gravity as additional proofs of an accumulation and increased density of atmosphere at the equator. But to my mind the dip of the magnetic needle affords still more striking evidence of such an arrangement of the atmosphere. From the equator to the poles, the dip gradually increases. Suppose then that the density of the atmosphere at every step in the same progess decreases, and we have the reason for the increased dip in the diminished density of the atmosphere, and the diminished resistance Consequent thereon. The dip increases

as the resistance to it diminishes. And further, the attractive power seated in

The waters of the ocean under the influence of the earth's centrifugal force are known to be greatly elevated at the equator. That seems to be the power which obeyed the Almighty fiat, "let the waters under the heaven be gathered together." This appears to be the power which first established and still maintains the level of the sea,

the earth which causes the needle to dip, combined with this distribution of the atmosphere will give to the needle a general polarity. It must necessarily point in the direction where it meets the least resistance.

These facts are submitted as evidence of an atmospherical accumulation and density at the equator. And proof of the extreme intensity of the solar light in the equatorial regions is unnecessary, that being a fact well known and universally admitted. We have then such an arrangement of atmosphere and solar light as proportions the degree of solar heat at any given place to the intensity of the light and the density of the atmosphere at that place, and as gives, just such a distribution of natural heat as, (with the exception of the anomalies presented by the Hymalayas) is found to exist. According to this theory it would be greatest and ascend highest within the tropics where the light is most intense and the atmospheric accumulation and density are greatest; and from thence its elevation would decline and its intensity decrease towards the poles. And this is the order we find in nature, there is the greatest heat, attaining the highest elevation, within the tropics; which (with the exception referred to) from thence gradually declines, and decreases in intensity, towards the poles.

The anomalies of the Hymalayas may, perhaps, be adduced as subversive of the theory here advanced; those anomalies, however, appear rather to strengthen than to weaken this theory. They are of that class of exceptions which prove the rule. This range of mountains, situate between 28° and 36° N. lat., extends in one continuous chain from 97° to 67° E. long., a distance, including sinuosities, of about 2,000 miles, presenting, throughout that immense range, a barrier towards the north of the mean height of 17,000 feet. And this is but the average elevation of the ridge, from which rise numerous lofty peaks, some of which attain upwards of 26,000 feet, and few of which rise less than 20,000 feet, above the level of the sea. On some parts of these mountains, the inferior line of perpetual congelation does not descend lower than 17,000 feet above the level of the sea; whereas the inferior line of perpetual congelation at the equator, is only 15,500 or 15,700 feet above

that level. But the most remarkable, and to our purpose by far the most important, of these anomalies is, that the heat, and the inferior line of perpetual congelation, appear to attain a much higher elevation on the northern than on the southern side of the Hymalayas; at least this inference fairly may be drawn from the statement, that "the extreme height of cultivation, on the southern slope of these mountains, is 10,000 feet, the height of habitation, 9,500. While on the northern slope, villages are found at 13,000 feet; and cultivation at 13,600 feet." Now, the earth's rotation and centrifugal force, will necessarily cause, and at all times keep up, a strong bearing or pressure of atmosphere from the poles towards the equator, which coming in contact with these mountains, will rush up, or be forced up, by its own momentum, to a considerable elevation against the northern side. And thus it will compress and condense itself, and produce the anomaly of the inferior congelation line attaining a higher elevation on the northern than on the southern side.

With regard to heat from compression of air, it is well ascertained that the temperature or action of atmospheric air is proportioned to its density, increasing where the density increases, and diminishing where it diminishes; and that its density is increased by compression, whether the compression be by mechanical means, or by the superincumbent weight of the atmosphere itself.

Hence

the reason why the temperature or action of the atmosphere diminishes as we ascend from the earth's surface. Air, by sudden compression, is made to ignite combustible substances. The temperature at the bottom of deep mines is greater than at the top. The deeper the mine, the greater the heat. The heat gradually increases with the depth. This is caused by the superincumbent pressure of the column of air which descends the pit. Proceeding from the poles to the equator, the temperature of the atmosphere increases. Ascending from the earth's surface, it decreases. We know that the density of the atmosphere decreases as we ascend from the earth's surface, and we have seen that it increases as we approach the equator.

By compression air also gives light, or becomes light. The heat and light from

175

collision are caused by the compression of air in the pores of the substances. All solid substances immersed in air must become thoroughly saturated with air. If they were so immersed in water, which is a much less subtile fluid, it would penetrate and saturate them. It would so saturate wood, iron, stone, or almost any other substance. It is evident, then, that the violent collision of substances must cause a sudden compression of air in the parts coming in contact, which is greater or less according to the flexibility of the substances. used. Stone and iron in collision, being rigid substances, give out sparks. The ordinary kinds of wood, being softer and more pliable, do not. It is a difficult operation to give one proof of these views which is desirable, namely, the collision of substances in vacuo. It is not an easy matter to maintain a vacuum for such a length of time, as to allow an experiment like this to be properly made. In order to try the experiment satisfactorily, the substances to be struck should lay for some time previously in vacuo, in order to extract the air out of them. Another, and a better proof, is to strike the substances in water, which not only displaces the air from the outward surface, but in some degree follows it into its retreats, the pores of the substances, and drives it out. This will give convincing evidence that neither light nor heat can be obtained by collision, in the absence of air.

Heat from friction is caused by the compression of air in the pores of solid substances; the compression being effected by the action of the substances in air. The axles of machinery would not heat, if the air could be excluded from them Perhaps the nearest approach to a perfect exclusion is to make the axles run in liquids. By friction, in air, substances may be heated red hot; but they can neither be heated red hot, nor heated in any considerable degree, nor, I think, heated at all, in water, because the air is excluded from them.

The light arising from collision and friction, also affords evidence that atmospheric air, under some modifications, gives light, or becomes light; and atmospheric air, being also (as no doubt it is) the fluid which produces dissolution in all cases of combustion, and which, modified in the process of combustion, be

Death of Joseph Lancaster,-This celebrated individual, founder of the Lancasterian system of education, died at Williamsburg, near New York, on the 24th instant, in consequence of his being run over the previous day. He was in his 61st year.

Iron Steam Ship for America.-The British and American Steam Navigation Company have this week contracted with Mr. John Laird, of Liverpool, (the builder of the iron steam vessel Rainbow, belonging to the General Steam Navigation Company)) for an iron steam ship of 1,200 tons, to be called the Atalanta, and intended to run between this country and the United States, in conjunction with the British Queen and the President. From the experience Mr. Laird has had in this description of naval architecture, and the speed, he has already attained in the vessels he has built, those well able to form an opinion on the subject, confidently predict that this vessel will reduce to ten days the average passage between Liverpool and New York.

Sulphur.-M. Maravigno, the Professor of Chemistry in the University of Catania, who possesses a very numerous collection of the crystallized sulphur of Sicily, refers the formation of this substance to the period of secondary rocks. He disputes the assertions of Professor Gemellaro, who pretends that sulphur owes its origin to the decomposition of mollusca, an assertion which has been reproduced in Germany by Professor Leonhard, of Heidelberg. He thinks, that, whilst the secondary formations were being deposited, the currents of acid hydrosulphuric gas, from the interior of the earth, came in contact with the blue marl, held in suspension in water, and that the acid, in decomposing, produced deposits of sulphur, which are still found mingled with the marl. He notices the deplorable system still used in Sicily for extracting sulphur, in which he says that 17 parts are lost out of 18. He then describs the different forms which the crystals present, the first of which has been discovered by him: it is that of a straight rectangular prism, the solid angles of which are truncated, and replaced by triangular facets.-Athenæum.

Savory's Clock.-Sir,-As no notice has been taken of a mistake in Nautilus's last paragraph (page 102), allow me to direct his attention to it. He says "It is evident there would be no difficulty in affixing a light index at the back of the transparent dial, &c."-thus having "two indices as in an ordinary clock, one for hours, the other for minutes." Now, "it is esident" that he is in error, forgetting, that as the arbor of the hour-hand is to be fixed to the transparent dial, therefore the works must be carried round it; consequently, at the expiration of an hour the framework of the watch will have made 1-12th of a revolution round the arbor of the hour-hand. Now, in the same time, the minute-hand arbor has made one revolution to the frame of the watch, which frame having made 1-12th of a revolution to the fixed dial, it follows that the minute-hand will be five minutes in ad

St. Pancras, Dec. 5, 1838. Steam Navigation to India.-The Indian Steam Ship Company have announced that their first vessel, the India, will be launched on the 3rd of January next, and be ready to take in stores in the Thames by the middle of April. The vessel is building by Messrs. Scott and Sons, and the engines by Messrs. Scott and Sinclair of Greenock; she is of 1,200 tons burthen, with accommodation for 80 cabin passengers, and 400 tons of goods. She is provided with a safety apparatus (against boiler bursting, we presume), and built with two strong bulkheads of plate iron across the engine-room, in order to confine accidental fire, and prevent a leak sprung in one division from spreading to another. It is also announced, that another vessel of 1,500 tons burthen is on the stocks, and that a third will be ready within eighteen months, and that three more are about to be commenced. With this number of vessels, it is expected that twelve voyages out and twelve voyages home will be performed in each year, allowing fifty-five days to accomplish the distance from Plymouth to Calcutta, by the Cape of Good Hope.

Steam-vessel Inspectors.-At a late meeting of the Town Council of Edinburgh, a letter was read from Mr. John Cook, W. S., of Moray Place, containing some suggestions for carrying into immediate operation the principle of an Inspector of Steam-boats. The plan proposed by Mr. Cook is this-1st, That the Council should appoint a Committee for this business. 2nd, That the Committee should appoint an Inspector of Steam -boats. 3rd, That the Committee should intimate to all the Proprietors and Captains of Steamboats sailing from Leith, Newhaven, and Granton, that their Imspector will inspect such vessels; and that the proprietors of each vessel will have to pay the cost of the inspection. 4th, That the Committee, after receiving the report from their Inspector, should publish a list of the steam-vessels which they approve of and consider safe, as well as a list of them which they do not consider seaworthy and the names of those the owners of which decline to permit them to be inspected, that the public may know what they are about. And, 5th, That the inspector should be renewed as often as the Committee should think fit.-Some of the members of Council expressed doubts whether they had the power to adopt the recommendation of Mr. Cook, and others thought that it might be a very good subject for the Council to petition Parliament upon. In the mean time, however, the letter was ordered to lie on the table.

Metropolitan Railway Map.-On Saturday next, 15th December will be published vol. xxix. of the Mechanics' Magazine, price 8s. 6d., illustrated with a Railway Map of the Metropolis, taking in a radius of 15 miles from the Post-offce. The limits of the two-penny and threepenny post deliveries are also shown in the Map. The Metropolitan Railway Map alone, stitched in a wrapper, price 6d., and on fine paper, coloured, ls. The Supplement to vol. xxix, price 6d.

The Railway Map of England and Wales continues on sale, in a neat wrapper, price 6d. ; and on fine paper, coloured, price is.

HEARLE'S PATENT SHIP AND HOUSE

PUMP.

Sir,-Perceiving that one of the correspondents of your highly valuable miscellany (No. 767,) has drawn your attention, and also that of your numerous readers, to "Hearle's patent ship and house pump," I beg leave to forward you a sketch of the same, with a few explanatory notes, that its peculiarities may be the better understood.

I am, Sir, your obedient servant,
JOHN MARE.
Foundry, Plymouth, July 31, 1838.

Description of engravings in the front page.-A, the arbor, working through two stuffing boxes, carrying, on the middle of its length, a lever or beam, to the ends of which are attached the bucket rods in the usual way.

B B, The handles, fitting on the square end of the arbor, at A, meeting at B. C, the air-vessel, containing the two cylinders.

D D, plugs, removeable at pleasure for attaching in their stead the suction hose.

F, plug, removeable at pleasure to introduce water into the engine, when, if by laying by unused, the bucket leathers, &c., may have become dry.

G G, openings, cast for the reception of the wooden handles, to be used when carrying the engine wherever it may be required.

This engine, it will be readily seen, does not, like the usual fire-engines, where the plunger is used, fill the cylinder, to force back the large body of water to be delivered. Therefore, the water does not pass through those multiplied tortuous windings of a plunger-pump, which materially increases the amount of friction, and consequently of labour also ;

this being a simple lift and force pump, and, by reason of its being completely enclosed within the air-vessel, it is at once exceedingly portable, and placed beyond the reach of accident or design to interfere with its efficiency.

The ease, also, with which it is worked, on account of the amount of friction being reduced to the minimum, and the large quantity of water delivered, has united to obtain for it the unqualified good opinion of all who have had occasion to use his pump, for whatever purpose. Its portability is. no inconsiderable feature.

An engine on the above construction, having two 6-inch cylinders, weighs but four cwt. when complete, and delivers about a hogshead of water per minute.

Directions for using the pump.-The pump, c, when required to be used for domestic purposes, as a common house or lifting pump, for raising water to a great height, is to be secured to its situation by four iron studs and forelocks, k, strongly fixed into stone or wood, in a similar manner to the working board, N, or cover of case, M, which accompanies it. A metal swivel-nut is to be soldered to the supply pipe from the well, and fixed to one of the screws E, in the bed L of the pump; the ascending pipe, if used as a lifting pump, is to be secured in the same manner, to the side screws D, or top screw F, of the air-vessel, as may be most convenient; particular care should be taken that the whole of the caps and screws be hove sufficiently to keep them air-tight, and that the leather washers are all in their places. Motion is given to the axis, A, by the two handles, B B, (which may be detached when needful), having wooden staves passing through them at H H, the two pumps within the air-vessel, C, are worked by levers projecting from the axis, A, which is furnished with glands or stuffing boxes, P P, easily adjusted. The wooden staves employed at H H, in working the pumps, are also made use of for transporting the engine with great readiness, by passing them through G G. The engine at all times should be kept filled with water, which will keep it in a fit state for use.

If the pump should be required to be used for fire, or other purposes, the swivel-nuts of the supply and ascending pipes are to be unscrewed, and the pump fixed on the working board; the suction hoses to be screwed on to either of the screws in the bed, and the delivery hoses to either of the screws in the side of the container or air-vessel;-on no account is the hose to be fixed to the screw on the top, as no compression of the air could take place, but should the engine not immediately draw its water, the upper cap to be unscrewed, and water poured in, which would instantly effect the purpose; the suction hoses, before screwed on, should be wetted.

Should any leakage arise, after long use, at the stuffing boxes, in the side of the container, and through which th