the jar was covered with thick cotton, the quantity of ice melted was increased: but even when the jar was plunged in a freezing mixture, more ice was melted by water of the heat of 41° than by boiling water. Very little difference occurred when the jar was in the temperature of 32° or 61o.

All these appearances might, I think, be accounted for in a fatisfactory manner on the principles we have affumed refpecting the manner in which heat is propagated in liquids; but without engaging ourselves at present too far in these abstruse speculations, let us take a retrospective view of all our experiments, and fee what general refults may with certainty be drawn from them. . . .

...

From the refults of all these experiments we may certainly venture to conclude that boiling-hot water is not capable of melting more ice when standing on its furface, than an equal quantity of water at the temperature of 41°, or when it is only nine degrees above the temperature of freezing!

This fact will, I flatter myself, be confidered as affording the most unquestionable proof that could well be imagined, that water is a perfect non-conductor of heat, and that heat is propagated in it only

in confequence of the motions which the heat occafions in the infulated and folitary particles of that fluid. P. 277.

We have followed the count in thefe experiments with unufual attention, because we deem them very important. We may be more concise in speaking of his application. The law of condenfation of water, in cooling, is productive of many great advantages. In cooling 22 degrees of Fahrenheit, the condenfation is ninety times greater when the water is boiling than at the mean temperature of England. The confequence is, that fresh water muft freeze flowly; and, when the furface is frozen, the water below, brought from the mean temperature of the earth to 40°, will afcend and prevent the increase of ice beyond a certain thickness, while on a thaw, it will diminish the under furface as faft as the increafed heat of the air corrodes the upper. Ice then, and fnow in a greater degree, keep the water at a moderate temperature, even in the coldest weather of the mot ungenial climates; and the ice is prevented from acquir ing a thickness which no fummer's fun could diffolve. The falt water, however, is not influenced by any fimilar law; but its depth prevents it from attaining fo great a degree of cold, and its faltnefs from being affected at the temperature of 32°. Its flux and reflux, and its currents on the furface, the balance of which is reciprocally fupplied by fuitable under currents, contribute to equalife the temperature. If, as we had occafion to remark, the currents of the ocean tend from the equator northward, we fhall fee additional reafons for affigning this office of equalifing temperature to the fea. We may, on probable grounds, fuppofe that the course of the currents is not from the equator to the fouth pole, and we can explain the difference by La Place's demonftration, that the hemifpheroids, of which this planet confifts, are not equal; but we fee the effect in the increased intensity of the cold in the fouthern hemifphere at equal latitudes.

But the ocean is not more ufeful in moderating the extreme cold of the polar regions, than it is in tempering the exceffive heats of the torrid zone; and what is very remarkable, the fitness of the fea water to serve this laft important purpofe is owing to the very fame caufe which renders it fo peculiarly well adapted for communicating heat to the cold atmosphere in high latitudes, namely, to the falt which it holds in folution.

The infight which this discovery gives us in regard to the nature of the mechanical procefs which takes place in chemical folutions is too evident to require illuftration;-and it appears to me that it will enable us to account in a fatisfactory mauner for all the various phænomena of chemical affinities and vegetation. Perhaps all the motions among inanimate bodies on the furface of the globe may be traced to the fame cause,-namely, to the non-conducting s power of fluids with regard to heat.'

As the condensation of falt water with cold continues to go on even long after it has been cooled to the temperature at which freth water freezes, thofe particles at the furface which are cooled by an immediate contact with the cold winds muft defcend, and take their places at the bottom of the fea, where they muft remain, till, by acquiring an additional quantity of heat, their specific gravity is again diminished. But this heat they never can regain in the polar regious, for innumerable experiments have proved, beyond all poffibility of doubt, that there is no principle of heat in the interior parts of the globe, which, by exhaling through the bottom of the ocean, could communicate heat to the water which refts upon it.

It has been found that the temperature of the earth at great depth under the furface is different in different latitudes, and there is no doubt but this is alfo the cafe with refpect to the temperature at the bottom of the fea, in as far as it is not influenced by the currents which flow over it; and this proves to a demonstration that the heat which we find to exift, without any fenfible change during fummer and winter, at great depths, is owing to the action of the fun, and not to central fires, as fome have too haftily concluded.

But if the water of the ocean, which, on being deprived of a great part of its heat by cold winds, defcends to the bottom of the fea, cannot be warmed where it defcends, as its specific gravity is greater than that of water at the fame depth in warmer latitudes, it will immediately begin to fpread on the bottom of the fea, and to flow towards the equator, and this muft neceflarily produce a current at the furface in an oppofite direction; and there are the most indubitable proofs of the existence of both these currents.

The proof of the exiftence of one of them would indeed have been quite fufficient to have proved the existence of both, for one of them could not poffibly exift without the other: but there are several direct proofs of the existence of each of them.

• What has been called the gulf stream, in the Atlantic Ocean, is no other than one of thefe currents that at the furface which moves from the equator towards the north pole, modified by the trade winds, and by the form of the continent of North America; and the progrefs of the lower current may be confidered as proved directly by the cold which has been found to exift in the fea at great depths in warm latitudes;a degree of temperature much below the mean annual temperature of the earth in the latitudes where it has been found, and which of course must have been brought from colder latitudes.

The mean annual temperature in the latitude of 6; has been determined by Mr. Kirwan, in his excellent treatife on the temperature of different latitudes, to be 39°; but lord Mulgrave found on the 20th of June, when the temperature of the air was 481o, that the temperature of the fea at the depth of 4680 feet was fix degrees below freezing, or 26° of Fahrenheit's thermometer.

On the 31st of Auguft, in the latitude of 69°, where the annual

temperature is about 38°, the temperature of the fea at the depth of 4038 feet was 32°; the temperature of the atmosphere (and probably that of the water at the surface of the fea) being at the fame time at 594°.

But a ftill more striking, and I might, I believe, fay an incontrovertible proof of the existence of currents of cold water at the bottom of the fea, fetting from the poles towards the equator, is the very remarkable difference that has been found to fubfift between the temperature of the fea at the furface and at great depth, at the tropic, though the temperature of the atmosphere there is fo conftant that the greateft changes produced in it by the seasons seldom amounts to more than five or fix degrees; yet the difference between the heat of the water at the furface of the fea, and that of the depth of 3600 feet, has been found to amount to no less than 31 degrées; the temperature above or at the furface being 84o, and at the given depth below no more than 53o.

It appears to me to be extremely difficult, if not quite impoffi ble, to account for this degree of cold at the bottom of the fea in the torrid zone, on any other fuppofition than that of cold currents from the poles; and the utility of these currents in tempering the exceffive heats of thofe climates is too evident to require any illuftration.' P. 302.

We can cheerfully join in our author's conclufion, that all is wifely and happily contrived for the best though we fee through a glafs darkly, we fee enough to admire and adore the benevolence and wifdom of the fupreme contriver of all.

The eighth effay contains the fubftance of the two papers published in the Philofophical Tranfactions, already quoted, and the ninth is on the fource of heat excited by friction,' published in the volume of Philofophical Tranfactions for 1798, and noticed by us in our XXIVth volume, N. A. p. 37. Our author's future labours, fome of which have recently appeared, we shall receive with pleasure and gratitude.

An Account of an Embaffy to the Kingdom of Ava. (Continued from Vol. XXIX. p. 371, New Arr.).

UMMERAPOORA, the prefent capital of the united kingdoms of Ava, Arracan, and Pegu, was founded by Minderagec Praw, a fucceffor of Alompra, either from vanity, or the fuperftitions infpired by judicial aftrology, a ftudy to which he was much addicted. Ummera poora is fituated about four miles north-east of Ava. In this fpot, a deep and extensive lake is formed by the influx of the river, through a narrow channel, during the fummer monfoon. It foon expands, and difplays a body of water a mile and half broad, and leven, or CRIT. REV. VOL. XXX. October, 1800.

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eight miles long. Its direction is, at firft, northerly, nearly parallel with the river, but it afterwards curves to the foutheaft, while its ftream gradually terminates in a morafs, thus forming a dry healthy peninfula. This fpot was arid and parched at the time of our author's arrival, though little above the level of the lake; and the ufual embankments, for the plantations of rice, were, from the uncommon drought, ufelefs: the formerly fertile grounds were an unproductive waste.

As foon as my vifitors took their leave, I made a furvey of our new habitation; it was a fpacious houfe of one story, raised from the ground fomewhat more than two feet, and better covered than Birman houfes ufually are; it confifted of two good fized rooms, and a large virando, or balcony; the partitions and walls were made of cane mats, with latticed windows in the fides: the hape of the roof was fuch as diftinguishes the houses of nobles: it was altoge ther a comfortable habitation, and well adapted to the climate, Mr. Wood had a fmaller houfe erected behind mine, and parallel to it, and Dr. Buchanan another at right angles. Small feparate huts were conftructed for the guard, and for our attendants; the whole was furrounded by a strong bamboo paling, which inclosed a court yard. There were two entrances by gates, one in front of my houfe, the other backwards; at each of thefe, on the outfide of the paling, was a fhed, in which a Birman guard was poïted to protect us from thieves, keep off the populace, and probably to watch and our movements.

report

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On tire fkirts of the fame grove, in a line with our dwelling, funilar houfes were erected for three Chinese deputies, who had arrived at Ummerapoora about two months before us: these personages were reprefented as compofing a royal'miffion from the imperial city of Pekin, but circumftances early led me to fufpect that their real character did not rife higher than that of a provincial deputation from Manchegee, or Yunan, the fouth-weft province of China, which borders on the kingdom of Ava, a conjecture that was afterwards confirmed. They had accompanied the governor of Bamoo, which is the frontier province, to the capital; and I undertood that their business was to adjust fome mercantile concerns. relating to the jee, or mart, where the commodities of the two empires are brought and bartered. It was not at all improbable that the miffion had been sanctioned by the authority of the emperor of China, efpecially as the principal member of it was a native of Pekin, and had lately come from thence: but the falfe pride of the Birman court fuggefted the puerile expedient of representing it to us as an imperial embassy, a distinction to which, I was privately

*

The Chinese feem to have been actuated by a policy equally abfurd, when they informed fir George Staunton, at the time of the formal introduction of lord Macartney, that" emhaffadors from Pegue" were present; and that Siam, Ava, and Pegue, were tributary to China:" fuch unworthy deceptions not being expected, could hurdly be guarded against. The courts of