way of accounting for them may be to furmife that our fun has been formerly fometimes more and fometimes lefs bright than it is at prefent. At all events, it will be highly prefumptuous to lay any great ftrefs upon the ftability of the prefent order of things; and many hitherto unaccountable varieties that happen in our feafons, fuch as a general feverity or mildness of uncommon winters or burning fummers, may poffibly meet with an eafy folution in the real inequality of the fun's

rays.

"A method of afcertaining the quantity or intenfenefs of folar light might be contrived by fome photometer or inftrument properly conftructed, which ought probably to be placed upon fome high and infulated mountain, where the influence of various caufes that affect heat and cold, though not entirely

removed, would be confiderably leffened. Perhaps the thermometer alone might be fufficient. For though the luftre of the fun fhould be the chief object of this research, yet, as the effect of light in producing expanfion in mercury feems to be intimately connected with the quantity of the incident folar rays, it may be admitted that all conclufions drawn from their action upon the thermometer will apply to the investigation of the brilliancy of the fun. And here the forms laid down by Mr. Mayer, in his little treatise De Variationibus. Thermometri accuratius definiendis, may be of confiderable fervice to diftinguish the regular caufes of the change of the thermometer from the adventitious ones, among which I place the probable inftability of the fun's luftre."

"THE

HE extraordinary circumftance of native gold being found in this vicinity, early excited my attention, and led me to feize the first opportunity that prefented itfelf, after my late arrival here, to infpect the place where the difcovery was made.

"I went thither on Tuesday, the 3d of this month, with Mr. Lloyd, of Havodynos, and Mr. Weaver. The former having given you fome account of the circumftances which attended the original difcovery, and, fince he left me, a favourable day having enabled me to take a fecond view of the adjacent coun

try, I fhall now attempt to describe the general appearance, and add fuch further information as has come to my knowledge.

"The workings which the peafantry recently undertook are on the north-eatt fide of the mountain Croughan Kinfhelly, within the barony of Arklow, and county of Wicklow, on the lands of the earl of Carysfort, wherein the earl of Ormond claims a right to the minerals, in confequence (as I have been informed) of a grant in the reign of king Henry the Second, by prince John, during his command of his father's forces in Ire

G 3

land:

land; which grant was renewed and confirmed by queen Elizabeth, and again by king Charles the Second. "The fummit of the mountain is the boundary between the counties of Wicklow and Wexford; feven English miles weft from Arklow, ten to the fouth-westward of Rathdrum, and fix fouth-wefterly from Cronebane mines; by eftimation about fix hundred yards above the level of the fea. It extends W. by N. and E. by S. and ftretches away to the north-eaftward, to Ballycoage, where fhafts have formerly been funk, and fome copper and magnetic iron ore has been found; and thence to the N. E. there extends a tract of mineral country, eight miles in length, running through the lands of BalTymurtagh, Ballygahan, Tigrony, Cronebane, Connery, and Kilmacoe, in all which veins of copper ore are found; and terminating at the flate quarry at Balnabarny.

"On the highest part of the I mountain are bare rocks, being a variety of argillite, whofe joints range N.N.E. and S.S.W. hade to the S.S.W. and in one part include a rib of quartz, three inches wide, which follows the direction of the trata. Around the rocks, for fome diftance, is found ground, covered with heath; defcending to the eaftward, there is fpringy ground, abounding with coarfe grats; and below that, a very extenfive bog, in which the turf is from four to nine feet thick, and beneath it, in the fubitratum of clay, are many angular fragments of quartz, containing chlorite, and ferruginous earth. Below the turbary the ground falls with a quick defcent, and three ravines are observed. The central one, which is the most confiderable, has been worn by torrents, which derive their fource from the

bog; the others are formed lowes down the mountain by fprings, which uniting with the former, below their junction the gold has been found. The fmaller have not water fufficient to wash away the incumbent clay, fo as to lay bare the fubftratum; and their beds only contain gravel, confifting of quartz with chlorite, and other substances of which the mountain consists. The great ravine presents a more interesting afpect; the water in its defcent has, in a very short distance from the bog, entirely carried off the clay, and confiderably worn down the fubftrata of rock, which it has laid open to inspection.

"Defcending along the bed of the great ravine, whofe general courfe is to the eastward, a yellow argillaceous fhiftus is first feen; the laminæ are much fhattered, are very thin, have a light hade to the S.S.W. and range E.S.E. and W.N.W. Included within the fhift, is a vein of compact barren quartz, about three feet wide, ranging N.E. and S.W.; below this is another vein, about nine inches wide, having the fame range as the former, and hading to the northward, confifting of quartz, including ferruginous earth. Lower down, is a vein of a compact aggregate fubftance, apparently compounded of quartz, ochraceous earth, chert, minute particles of mica, and fome little argillite, of unknown breadth, ranging E. and W. hading faft to the fouthward, and including ftrings of quartz, from one to two inches thick, the quartz containing ferruginous earth. The yellow argillaceous fhiftus is again feen with its former hade and range; and then, adjacent to a quartz vein, is laminated blue argillaceons fhiftus, ranging N.E. and S.W. and hading S. E.; which is after

wards

wards feen varying its range and hade, running E.N.E. and W.S.W. and hading N.N.W.; lower down, the blue fhift is obferved more compact, though, ftill laminated. The ground, lefs fteep, becomes fpringy, is inclofed, and the ravine, hallower, has depofited a confider, able quantity of clay, fand, and gravel. Following the courfe of the ravine, or, as it may now more properly be called, the brook, arrive at the road which leads to Arklow; here is a ford, and the brook has the Irish name of Aughatinavought (the river that drowned the old man); hence it defcends to the Aughrim river, just above its confluence with that from Rathdrum, which, after their junction, take the general name of the Ovo, that, difcharging itself into the fea near the town of Arklow, forms an harbour for vessels of fmall burthen.

"The lands of Ballinvally are to the fouthward, and the lands of Ballinagore to the northward, of the ford, where the blue fhiftus rock, whofe joints are nearly vertical, is feen ranging E.N.E. and W.S.W. including fmall strings of quartz, which contain ferruginous earth. The fame kind of earth is alfo feen in the quartz, contained in a vein from ten to twelve inches wide, ranging E.N.E. and W.S.W. and hading to the fouthward, 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 fubftances wafhed down from the mountain, which on the fides have accumulated to the depth of about twelve feet. A thin ftratum of vegetable foil lies uppermoft; then clay, mingled with fine fand, compofed of fmall particles of quartz, mica, and fhift; beneath which the fame fubitances

are larger, and conftitute a bed of gravel, that alfo contains nodules of fine grained iron ftone, which produces 50 per cent. of crude iron : incumbent on the rock, are large tumblers of quartz, a variety of argillite and fhiftus; many pieces of the quartz are perfectly pure, others are attached to the fiftus, others contain chlorite, pyrites, mica, and ferruginous earth; and the arfenical cubical pyrites fre quently occurs, imbedded in the blue fhiftus. In this mass of matter, before the workings began, the brook had formed its channel down to the furface of the rock, and between fix and feven feet wide, but in times of floods extended itself entirely over the valley,

"Refearches have been made for the gold, amidft the fand and gravel along the run of the brook, for near half a mile in length; but 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 fuccefs: within that space, the valley is tolerably level, and the banks of the brook have not more than five feet of fand and gravel above the rock; added to this, it takes a small turn to the fouthward, and, confequently, the rude furfaces of the fhiftus rock in fome degree crofs its courfe, and form natural impediments to the particles of gold being carried further down the ftream, which still lower has a more rapid defcent; befides, the rude manner in which the country peo ple worked, feldom enabled them to penetrate to the rock, in thofe places where the fand and gravel were of any material depth. Their method was, to turn the courfe of the water wherever they deemed neceffary, and then, with any in ftruments they could procure, to

dig holes down to the rock, and by wathing, in bowls and fieves, the fand and gravel they threw out, to feparate the particles of gold which it contained; and from the flovenly and hafty way in which their operations were performed, much gold moft probably escaped their fearch; and that indeed actually appears to have been the cafe; for fince the late rams wahed the clay and gravel which had been thrown up, gold has been found lying on the furface. The fituation of the place, and the conftant command of water, do, however, very clearly point out the great facility with which the gold might be separated from the trafh, by adopting the mode of working practifed at the best managed tin ftream works in the county of Cornwall; that is, entirely to remove (by machinery) the whole cover off the rock, and then wash it in proper buddles and fieves. And by thus continuing the operations, conftantly advancing in the ravine towards the mountain, as long as gold fhould be found, the vein that forms its matrix might probably be laid bare.

"The difcovery was made public, and the workings began, early in the month of September laft, and continued till the 15th of October, when a party of the Kildare militia arrived, and took poffeffion by order of government; and the great concourfe of people, who were bufily engaged in endeavouring to procure a fhare of the treafure, immediately defifted from their labour, and peaceably retired. "Calculations have been made, that during the foregoing period, gold to the amount of three thoufand pounds Irish fterling was fold to various perfons; the average price was three pounds fifteen fhillings per ounce; hence eight hun

dred ounces appear to have been collected within the fhort fpace of fix weeks.

"The gold is of a bright yellow colour, perfectly malleable; the fpecific gravity of an apparently clean piece 19,000. A fpecimen, affayed here by Mr. Weaver, in the moift way, produced from 24 grains, 22 grains of pure gold, and 14 of filver. Some of the gold is intimately blended with, and adherent to quartz; fome (it is faid) was found united to the fine grained iron ftone, but the major part was entirely free from the matrix; every piece more or lefs rounded on the edges, of various weights, forms, and fizes, from the molt minute particle up to 2 oz. 17 dwts.; only two pieces are known to have been found of fuperior weight, and one of those is 5, and the other 22 ounces,

"I much regret not having been prefent when the work was going on, that I might have feen the gold as found, before prepared for fale by breaking off any extraneous matter that adhered; for in that ftate, a proper attention to the fubftances with which it was united, and a fubfequent diligent infpection of the feveral veins that range through the mountain, might affift towards the difcovery of that from whence it was detached,

"I fhall fhortly return to England; and on my arrival, will fend fpecimens of the gold, and of the different fubftances of the mountain, to be depofited (if you think proper) in the collection of the Royal Society,

"And am, with great refpect, &c.

" ABRAHAM MILLS. "The bearings are all taken by the compafs, without allowing for the variation.

"Befides

"Befides thefe accounts of the gold found in Ireland, the following information has been received on that fubject.

"William Molefworth, efq. of Dublin, in a letter to Richard Molefworth, efq. F.R.S. writes, that he weighed the largest piece of gold in his balance, both in air and water; that its weight was 20 oz. 2 dwts. 21 gr. and its fpecific gravity, to that of fterling gold, as iz to 18. Alfo that Richard Kirwan, efq. F.R.S. found the fpecific gravity of another fpecimen to be as 13 to 18. Hence, as the gold was worth 4 an ounce, Mr. William Molefworth concludes, that the fpecimens are full of pores and cavities, which in

"D

ISEASES, the tendency of

which is fatal, and the occurrence frequent, peculiarly claim the attention of the practical phyfician; while morbid affections, which appear more rarely, and prefent unufual phænomena, more especially astract the enquiries of thofe whofe object is the extenfion of general fcience. The difeafe termed Plica Polonica is of the latter clafs. It is endemic in Poland, and feldom, if ever, obferved in any other part of Europe. During a long ftay at Breslau in Silefia, I had frequent opportunities of obferving this difpale and, as it is at prefent little known in Britain, I trust a brief narration of the principal circumfrances connected with it will not prove uninteresting

:

"Both fexes are equally liable to the attacks of plica. It ufually appears during infancy; and but feldom after the age of twenty. When once produced, it continues during the remainder of life. The acceffion of the complaint is in general preceded by irregular fpafmodic affections, pains in different parts of the body, a flow fever, and various difeafes of the eyes; all which ceafe immediately on the appearance of the Plica.

"The diforder confifts in a præternaturally rapid growth of the hair, with a copious fecretion of a vifcid matter from its bulbs. For the most part, the hairs of the head are alone affected; and that only in peculiar parts. In thefe, the hairs grow confiderably longer than