Art. 11. Obfervations on Refpiration. By the Rev. Jofeph Priestley, L. L. D. F.R.S.

It is admitted that dephlogifticated air is confumed in the act of refpiration, and that fixed air, which is admitted to confift of dephlogifticated air, united with fome inflammable and acidifiable bafis, is emitted. But whether any portion of the dephlogifticated air which difappears, be abforbed by the blood, remained to be proved. It is evident that a previous requifite for afcertaining this, muft confift in determining, as exactly as poffible, the quantity of dephlegifticated air which enters into the formation of a given mafs of fixed air. Dr. Priestley therefore began, by inftituting a fet of experiments for this purpose, in which charcoal was burned in dephlogifticated air, and in common air. These fhewed that three-fourths of the weight of fixed air consist of dephlogisticated air.

Having done this, the Doctor proceeded to afcertain how much fixed air was actually formed by breathing a given quantity both of atmospherical and of dephlogifticated air, in order to determine whether any part of it remained to enter the blood after forming this fixed air. The refult of his trials proved, that three times as much of the air entered the blood as did not, and that this air was not of the purest kind, but contained fome phlogisticated air. Dr. Priestley accounted for this fact at first, by fuppofing that the phlogifticated and dephlogifticated airs are not fo loofely mixed as has been imagined; but upon the fuggeftion of Dr. Blagden, he thinks it more probable that the deficiency of phlogisticated air was owing to the greater proportion of it in the lungs after the process than

before.

Art. 12. An Account of the trigonometrical Operation, whereby the Distance between the Meridian of the Royal Obfe satories of Greenwich and Paris has been determined. By MajorGeneral William Roy, F. R. s. and A. s.

The operations of which this paper contains an account, confer honour on the nation, on the fovereign, on the intelligent and active obfervers, and other promoters of it, and, though laft, not least, on the inftrument-maker Ramfden. The general, however, makes great complaints of his delay in finishing the apparatus, into the caufe of which, whether arifing from negligence or other more latent caufes, we have no difpofition to enquire.

After giving an account of fome previous fteps, and a fhort hiftory of the proceedings, general Roy enters upon his operations. The paper is divided into eight fections, and a concluding fection.

The first fection contains a defcription of the apparatus made use of in the measurement of the bafe of verification in Romney marsh. This was performed with a curious fteel

chain, the expanfion of which, for every degree of change of temperature, was found and allowed for. The true length of the bafe, in the temperature of 62° of Fahrenheit, was 28532.92 feet.

The fecond fection contains a general defcription of the great inftrument with which the angles were obferved in the trigonometrical obfervation. For this, as well as almost every other part of the prefent memoir, we muft refer to the Tranfactions; because it would be in vain to attempt to render any defcription intelligible without the plates. The inftrument itfelf, which is very loofely defcribed, confifts of an horizontal circle of three feet diameter, divided into degrees and quarter parts, or portions of 15 minutes each. Two microfcopes diametrically oppofite, ferve to read off the angular quantities obferved; the fubdivifions being effected by a notched plate divided into fifteen minutes, and a micrometer fcrew, which fubdivides thofe minutes into feconds in the field of view of the microscope. Two achromatic telescopes, each of thirty-fix inches focal length, with double object glaffes of 2 inches aperture, belong to the inftrument, and ferve to make the obfervations. One of these lies exactly under the centre of the inftrument, and has a fmall vertical motion upon an axis; the other is fupported upon a pillar, which rifes out of, or paffes through the centre of the horizontal circle. This telescope is mounted upon a tranfit axis, and carries a femi-circle of twelve inches diameter, for the purpose of taking altitudes. The whole inftrument weighs about two hundred pounds.

The third fection contains a defcription of various articles of machinery, and the diftinction of the ftations into two fets. Thefe articles are a portable scaffold, a tripod ladder, flag ftaff, tripod for white lights, and a portable crane.

Section the fourth contains a calculation of the series of triangles extending from Windfor to Dunkirk. In these calculations, which are tabulated, we obferve with furprize and fatisfaction, that the fum of the three obferved angles of the feveral triangles, allowance being made for the excefs arifing from the fphericity of the earth's furface, never differed fo much as three feconds from two right angles, and in general the difference was much less than that quantity.

The fifth fection is employed on the difference between horizontal angles on a sphere and fpheroid. The fixth fection exhibits the manner of determining the latitudes of the stations; the application of the pole-ftar obfervations to computations on different fpheres, and alfo on Mr. Bouguer's spheroids, for the determination of the differences of longitude, together with the ultimate refult of the trigonometrical operations. The longitude of Dunkirk from Greenwich proves to be 2°. 22′′, 3.9, and that of Paris 20.19 19.42, and the distance between

the

the parallels of latitude of Greenwich and Paris is 160655 fathoms. The length of a degree of the meridian in latitude 50°. 9. 27', is 60840 fathoms.

A table of the degrees of great circles, and of longitude for middle latitudes is alfo given, and other valuable refults, which on account of our intended brevity, and for other obvious reafons, we cannot even completely enumerate. It was found that the terrestrial refraction diminishes as the heights of the ftations above the fea increafe, and that at particular times at leaft it is much greater than has hitherto been fuppofed, even to between half and one third part of the arc of distance, inftead of being only one ninth or one fourteenth.

Among other objects of value which were obtained in this extenfive purfuit, a fet of fecondary triangles' were obferved for the improvement of the maps of the country, and the plan of the city and its environs. The account is concluded with recommendations and advice for extending trigonometrical operations over Great-Britain.

The meteorological journal contains, as ufual, the temperature, the ftanding of the barometer, the rain, the direction and ftrength of winds, and the weather. The whole is tabulated for months at the end of the journal, and the annual medium is thermometer without 49°. 5', thermometer within 56°. 5′ barometer 29.79, and rain 21.976 inches.

ART. XI. Bruce's Travels to difcover the Source of the Nile. [Continued from Vol. VII. p. 393]

IT may be matter of furprife, in looking back on the preceding numbers, that at the beginning of the fifth extract, the reader fhould find himself advanced no farther than to the threshold of Abyffinia: we cannot, however, regret, or confider as fuperfluous, the communication of a fingle period: whatever we have hitherto presented to the reader, is either characteristic of the author, or relative to his defign: the difcovery, for which these travels were undertaken, is perhaps the leaft interesting part of the work, perhaps only a brilliant phantom; it certainly occupies the smallest part of the book, and in our opinion bears no greater proportion to the materials with which it is furrounded, than the images of our ladies of Loretto or Einfidlen bear to thofe ornaments of gold and diamonds with which they dazzle the multitudes that proftrate themfelves before them. Quota pars virgo fui?

Having thus obviated an objection, which may have been formed by the impatience of tome readers, we proceed to analyse the remaining chapters of the fifth book, vol. III. p. 88. Our author's journey from Arkeeko lay over the mountain of Taranta, a ftupendous mafs, and, as he fuppofes, one of the highest in the world, the point of which is buried in the VOL. VIII. E clouds,

clouds, and very rarely feen, but in the clearest weather; at other times abandoned to perpetual mift and darkness, the feat of lightning, thunder, and of ftorm.' By this road he arrived at Dixan, a frontier town: we extract the account of the fingular trade carried on at this neft of adventurers.

It is true of Dixan, as, I believe, of moft frontier towns, that the bad people of both contiguous countries refort thither. The town, as I before have faid, confifts of Moors and Chriftians, and is very well peopled; yet the only trade of either of thefe fects is a very extraordinary one, that of felling of children. The Chriftians bring fuch as they have stolen in Abyffinia to Dixan as to a fure depofit; and the Moors receive them there, and carry them to a certain market at Mafuah, whence they are fent over to Arabia or India. The priests of the province of Tigré, efpecially thofe near the rock Damo, are openly concerned in this infamous practice; and fome of these have been licensed by Michael to carry it on as a fair trade, upon paying fo many firelocks for each dozen or score of flaves.

Nothing can elucidate the footing upon which this trade ftands better than a tranfaction which happened while I was in Ethiopia, and which reached Gondar by way of complaint from Masuah, and was toldme by Michael himself.

Two priefts of Tigrè, whose names I have forgot, had been long intimate friends. They dwelt near the rock Damo. The youngest was married, and had two children, both fons; the other was old, and had none. The old one reproved his friend one day for keeping his children at home idle, and not putting them to fome profeffion by which they might gain heir bread. The married priest pleaded his poverty and his want of relations that could affift him; on which, the old prieft offered to place his eldest fon with a rich friend of his own, who had no children, and where he should want for nothing. The propofal was accepted, and the young lad, about ten years of age, was delivered by his father to the old prieft, to carry him to this friend, who sent the boy to Dixan and fold him there. Upon the old prieft's return, after giving the father a fplendid account of his fon's reception, treatment, and prospects, he gave him a piece of cotton cloth, as a prefent from his fon's patron.

The younger child, about eight years old, hearing the good fortune of his elder brother, became fo importunate to be allowed to go and vifit him, that the parents were obliged to humour him, and confent. But the old prieft had a fcruple, faying he would not take the charge of fo young a boy, unlefs his mother went with him. This being fettled, the old priest conveyed them to the market at Dixan, where he fold both the mother and the remaining child.

6

Returning to the father, the old prieft told him, that his wife would ftay only fo long, and expected he would then fetch her upon a certain day, which was named. The day being come, the two pricfts went together to fee this happy family; and, upon their entering Dixan, it was found that the old prieft had fold the young one, but not to the fame Moor to whom he had fold his family. Soon after, thefe two Moors, who had bought the Chriftians, becoming partners in the venture, the old prieft was to receive forty cottoncloths, that is, 10l. fterling, for the husband, wife, and children.

The payment of the money, perhaps the refentment of the family trepanned, and the appearance of equity which the thing itfelf bore,

fuggefted

fuggefted to the Moorish merchants that there was fome more profit, and not more risk, if they carried off the old priest likewife. But as he had come to Dixan, as it were under public faith, in a trade that greatly interested the town, they were afraid to attempt any thing against him whilft there. They began then as it were to repent of their bargain, from a pretended apprehenfion that they might be ftopped and questioned at going out of town, unless he would accompany them to fome fmall diftance; in confideration of which, they would give him, at parting, two pieces of cloth to be added to the other forty, which he was to take back to Tigrè with him upon his

return.

The beginning of fuch expeditions is in the night. When all were afleep, they fet out from Dixan; the buyers, the feller, and the family fold; and, being arrived near the mountain where the way turns off to the defert, the whole party fell upon the old prieft, threw him down, and bound him. The woman infifted that she might be allowed to cut, or tear off the little beard he had, in order, as the faid, to make him look younger; and this demand was reckoned too juft to be denied her. The whole five were then carried to Mafuah; the woman and her two children were fold to Arabia; the two priests had not fo ready a market, and they were both in the Naybe's house when I was at Mafuah, though I did not then know it.

The Naybe, willing to ingratiate himself with Ras Michael at a fmall expence, wrote to him an account of the transaction, and offered, as they were priests, to restore them to him. But the Ras returned for anfwer, that the Naybe fhould keep them to be his chaplains; as he hoped, fome day, he would be converted to the Chriftian faith himself; if not, he might fend them to Arabia with the reft; they would ferve to be carriers of wood and drawers of water; and that there still remained at Damo enough of their kind to carry on the trade with Dixan and Mafuah.

This ftory I heard from Ras Michael himfelf, at his granddaughter's marriage, when he was feafting and in great fpirits. He, and all the company, laughed heartily; and though there were in the room at least two dozen of priests, none of them feemed to take this incident more feriously than the reft of the company. From this we may guefs at the truth of what the catholic writers advance, with regard to the refpect and reverence fhown to the priesthood by the government and great men in Abyffinia.'

In the fourth and fifth chapters, Mr. B. through a variety of entertaining incidents, and very picturefque defcriptions, profecutes his journey from Dixan to Adowa, the prefent capital of Tigré; vifits the remains of the Jefuits convent of Tremona, enters the plain, where once ftood Axum, the sup pofed capital of ancient Abyffinia. P. 129.

The ruins of Axum are very extenfive; but, like the cities of ancient times, confift altogether of public buildings. In one square, which I apprehend to have been the center of the town, there are forty obelisks, none of which have any hieroglyphics upon them. There is one larger than the reft ftill ftanding, but there are two ftil! larger than this fallen. They are all of one piece of granite; and on the top of that which is ftanding there is a patera exceedingly well carved

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