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ceous schistus is first seen; the la. minæ are much shattered, ate very thin, have a sight hade to the SSW, and range ESE and WNW. In cluded within the schist, is a vein of compact barren quartz, about three feet wide, ranging NE and SW; below this is another vein, about nine inches wide, having the same range as the former, and had. ing to the northward, consisting of quartz, including ferruginous earth. Lower down, is a vein of a compact aggregate substance, ap. parently compounded of quartz, ochraceous earth, chert, minute particles of mica, and some little argillite, of unknown breadth, ranging E and W, hading fast to the southward, and including strings of quartz, from one or two inches thick, the quartz containing ferruginous earth. The yellow ar. The yellow ar. gillaceous schistus is again seen with its former hade and range; and then adjacent to the quartz vein, is laminated blue argillaceous schis. tus, ranging NE and SW, and hading SE; which is afterwards seen varying its range and Hade, running ENE and WSW, and hading NNW; lower down, the blue schist is observed more compact, though still laminated. The ground less steep, becomes springy, is inclosed, and the ra vine, shallower, has deposited a consid.r. · able quantity of clay, sand, and gravel. Following the course of the ravine, or, as it may now more properly be cal ed, the brook, ar rive at the road which leads to, Arklow; here is a ford, and the brook has the Irish name of Aughatnought (the river that drowned the old man); hence it descends to the Aughrim river, just above its confluences with that

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from Rathdrum, which, after their junction, take the general name of the Ova, that discharging itself into the sea near the town of Arklow, forms an harbour for vessels of small burden.

The lands of Ballinvally are to the southward, and the lands of Ballinagore to the northward of the ford, where the blue schistus rock, whose joints are nearly verti cal, is seen ranging ENE and WSW, including small strings of quartz, which contain ferruginous earth.

The same kind of earth is also seen in the quartz, contained in a vein from ten to twelve inches wide, ranging ENE and WSW, and hading to the southward which has been laid open in forming the Arklow road.

Here the valley is from twenty to thirty yards in width, and is covered with substances washed down from the mountain, which on the sides have accumulated to the depth of about twelve feet. A thin stratum of vegetable soil lies uppermost; then clay, mingled with fine sand, composed of small particles of quartz, mic, and schist; beneath which the same substances are larger, and co istitu e a bed of gravel, that also è intains nodules of fine grained iron stone, which prodices 50 per cent. of crude 1.50 iron:* idêumbent on the rock are largertum Hers of quartz, a variety of arg i ani schistus; many pieces of the quartz are perfectly pare, others etched to the schis. tus, others contain chlórite, pyrites, mica, and ferruginous earch; and the arsenical cubical pyrites frequently occur, imbedded in the blue schistus. In this mass of matter, before the workings began, the brook had formed Cc 2

its

its channel down to the surface of the rock, and between six and seven feet wide, but in times of floods extended itself entirely over the valley.

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Researches have been made for the gold, amidst the sand and gravel along the run of the brook, for near half a mile in length; bet it is only about one hundred and fifty yards above, and about two hundred yards below the ford, that the trials have been attended with much success within that space the valley is tolerably level, and the banks of the brook have not more than five feet of sand and gravel above the rock; added to this, it takes a small turn to the south. ward, and, consequently, the rude surfaces of the schistus rock in some degree cross its course, and form natural impediments to the particles of gold being carried fur. ther down the stream, which still lower has a more rapid descent; besides, the rude manner in which the country people worked, seldom enabled them to penetrate to the rock, in those places where the sand and gravel were of any material depth, Their method was, to turn the course of the water wherever they deemed necessary, and then, with any instruments they could procure, to dig holes down to the rock, and by washing, in bowls and sieves, the sand and gravel they threw out, to separate the particles of gold which it contained; and from the slovenly and hasty way in which their operations were performed, much gold most probably escaped their search; and that indeed actually appears to have been the case, for since the late rains washed the clay and gravel which had been thrown up,

gold has been found lying on the surface. The situation of the place, and the constant command of wa ter, do, however, very clearly point out the great facility with which the gold might be separated from the trash, by adopting the mode of working practised at the best managed tin stream works in the county of Cornwall; that is, en tirely to remove (by machinery) the whole cover off the rock, and then wash it in proper buddles and sieves. And by thus continuing the operations, constantly advanc. ing in the ravine towards the mountain, as long as gold should be found, the vein that forms its matrix might probably be laid bare.

The discovery was made public, and the workings began, early in the month of September last, and continued till the 15th of Cctober, when a party of the Kildare mili. tia arrived, and took possession by order of government; and the great concourse of people, who were busily engaged in endeavour. ing to procure a share of the trea sure, immediately desisted from their labour, and peaceably retired.

Calculations have been made, that during the foregoing period, gold to the amount of three thousand pounds Irish sterling was sold to various persons; the average price was three pounds fifteen shil. lings per ounce; hence eight hun. dred ounces appear to have been collected within the short space of

six weeks.

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grains, 22 grains of pure gold, and I of silver. Some of the gold is intimately blended with, and adherent to quartz; some (it is said) was found united to the fine grained iron stone, but the major part was entirely free from the matrix; every piece more or less rounded on the edges, of various weights, forms, and sizes, from the most minute particles up to 2 oz. 17 dwt.; only two pieces are known to have been found of superior weight, and one of those is 5, and the other 22 ounces.

Í much regret not having been present when the work was going on, that I might have seen the gold as found, before prepared for sale by breaking off any extraneous matter that adhered; for in that state, a proper attention to the substances with which it was united, and a subsequent diligent inspection of the several veins that range through the mountain, might a sist towards the discovery of that from whence it was detached.

I shall shortly return to England; and on my arrival, will send specimens of the gold, and of the different substances of the moun. tain, to be deposited (if you think proper) in the collection of the Royal Society.

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And am, with great respect, &c. ABRAHAM MILLS.

The bearings are all taken by the compass, without allowing for the

variation.

BESIDES these accounts of the gold found in Ireland, the following information has been received on that subject.

William Molesworth, esq. of Dublin, in a letter to Richard

Molesworth, Esq. F. R. S. writes, that he weighed the largest piece of gold in his balance, both in air and water; that its weight was 20oz. 2 dwt. 21 gr. and its specific gravity, to that of sterling gold, as 12 to 18. Also that Richard Kirwan, Esq. F. R. S. found the specific gravity of another specimen to be as 13 to 18. Hence, as the gold was worth 41. an ounce, Mr. William Molesworth concludes that the specimens are full of pores and cavities, which increase their bulk, and that there are some extraneous substances, such as dirt. or clay, contained in those ca vities.

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This opinion was discovered to be well founded, by cutting through some of the small lumps..

STANESBY ALCHORNE, Esq. his, majesty's assay-master at the Tower of London, assayed two specimens of this native gold. The first appeared to contain, in 24 carats,

21 of fine gold; 1 of fine silver;

of alloy, which seemed to be copper tinged with a little iron.

The second specimen differed only in holding 21 instead of 219 of fine gold.

Major John Brown, of the royal engineers, transmitted to the right hon. Thomas Pelham, a sketch of the spot where the gold was found, which Mr. Pelham has obligingly permitted to be engraved, for the ue of the Royal Society.

C. B.

On the Clif lt on high Mountains, and at grent Depths. From Dr. Hunter'sTranslation of Euler's Let. ters to a German Princess.

IT appears very surprizing, that

we should feel the ame degree of cold in all regions, after we have risen to acertain height, say 24,000 feet; considering that the variations with respect to heat, on the earth, not only in the different climates, but in the same country, at differ ent seasons of the year, are so per. ceptible This variety, which takes place at the surface of the globe, is undoubtedly occasioned by the sun. It appears, at first sight, that his influence must be the same above and blow, especially when we reflect, that a height of 24,000 feet, or a mile, though very great with respect to us, and even far beyond the height of the loftiest mountains, is a mere nothing, com. pared to the distance of the sun, which is about thirty millions of miles*. This is therefore, a very important difficulty, which we must endeavour to solve. For this purpose, I begin with remarking, that the rays of the sun do not communicate heat to any bodies, but such as do not grant them a free passage. You know that bodies, through which we can dis. cern objects, are denominated trans. parent, pll: cid, and diaphonous. These bodies are glars, crystal, diamond, water, and several other liquids, though some are more or less transparent than others. Che of these transparent bodies being exposed to the sun, is not heated to such a degree as a body.not transpafent; as wood, iron, &c. Bodies not transparent are de ominated opque. A burning glass, for ex. ample, by transmitting the rays of the sun, sets on fire opaque bodies, while the glass itself is not sensibly heated. Water exposed to the sun

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becomes somewhat warm, only be cau-e it is not perfectly transparent; when we see it considerably heated by the sun at the brink of ri.

vers, it is because the bottom, be irg an opaque body, is heated by the rays which the water transmits. Now, every heated body comme. nicates that hat to all adjoining bodies; the water according y de rives heat from the bottom. If the water be very deep, so that the rays cannot pene.rate to the bottom, it has no perceptible heat, though the sun bears upon it.

As air is a very transparent body, to a much higher degree than glass or water, it follows, that it cannet be heated by the sun, because the rays are freely transmitted through it. The heat which we frequently feel in the air, is communicated to it by opaque bodies, which the rays of the sun have heated; and were it possible to annihilate all these bodies, the air would scarcely un. dergo any change in its temperature by the rays of the sun exposed to it or not, it would be equally cold. But the atmosphere is not perfectly transparent: it is even sometimes so loaded with vapours, that is loses almost entirely its transparency, and prevents only a thick fog. When the air is in this state, the rays of the sun have a more power. ful influence upon it, and heat it immediately.

But these vapours rise to no great height; at the height of 24,000 feet, and beyond, the air is so subtile and so pure, that it is perfectly transparent; and for this reason the rays of the sun cannot immediately produce any effect upon it. This air is likewise tom

Mrler always means German miles, of 4000 fathom each, or somewhat under 43 miles English.-E. E.

remote

emote from terrestrial bodies, to ceive a communication of heat rom them; they act only upon such as are adjacent. Hence you will easily perceive, that the rays of the sun cannot produce any ef. fect in regions of the air very much elevated above the surface of the earth; and that the same degree of cold must always, and universally, pievail in such regions, as the sun has no influence there, and as the heat of terrestrial bodies cannot be communicated so far. This is nearly the case on the sumipt of very nigh mountains, where it is always much colder than on plains en in vallies*.

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The city of Quito in Peru, is most ander the equator, and were to form our judgment from its bai on the globe we would ose it oppressed with intoler heat; the air, however, i abundantly temperate, and differs very little from that of Paris Quito is situated at a great height. above plantel srface of the earth. In ging to it from the sea shore, you have to ascend for several days it is accordingly built in an eleva tion equal to that of our highest mountains, though surrounded by others still much higher, called the Cordeliers. This last circumstance would afford a reason for thinking,

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that the air there must be as hot as at the surface of the earth, as it is contiguous on all sides, to the opaque bodies, on which the rays of the sun fall. The objection is solid; and no solution can be given but this: that the air at Quito, being very elevated; must be much more subtile, and of less gravity than with us; and the barometer, which always stands considerably lower, incontestibly proves it.

Afr of such a quality is not so susceptible of heat as common air, as it must contain less vapour and other particles which usually float in the atmosphere; and we know by experience, that air, very much loaded, is proportionably suscepti ble of heat. I must here subjoin another phenomenon, no less sur prising: in very deep pits,, and lower still, if it were still possible to descend, the same degree of heat. always, and universally prevails, and nearly for the same reason.. As the rays of the sun exert their. influence only on the surface of the. earth, and as the heat which they there excite communicates itself. up and down, this effect, at very great depths, is almost imperceptible. The same thing holds respecting considerable height. This elucidation will, I flatter myself, prove satisfactory+.

Account

*There are clouds, however, above these mountains, and in almost as great a quantity as above the plains, which is demonstrated by the snows which cover the highest summits. There are few naturalists who h ́ve not been surprised by clouds in their excursions upon the mountains. The heat that is felt when suck clouds are formed, must be attributed almost entirely to the transmission of the water which found itself dissolved in the air, under the form of elastic fluid, to a liquid state. The heat of the solar rays, intercepted by the cloud, can produce ne change in the inferior temperature, as it would have been transmitted from the ground.-F. E.

The reason which professor Euler assigns for the cold that prevails in the higher regions of the atmosphere seems plausible, but will not stand an accurate quamination. Light is 'much impaired in its passage through thêsatumsphere,

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