If we abftract from the local fituation and circumftances of the place, the temperature will be expreffed with tolerable accuracy by a formula firft propofed by the celebrated aftronomer Mayer. Let / denote the fine of the latitude; then the medium annual temperature will be 84° 53°X / by Farenheit's fcale. Hence the increment of temperature correfponding to one degree's advance to the equator is equal to the fine of double the latitude. Between the tropics the variation of temperature is fmall; it is greatest at the latitude of 45°, and again diminishes as we approach to the pole. It fcarcely ever freezes in lower latitudes than 35°, unless in very elevated places, nor hails in higher latitudes than 60°. Between the tropics the difference is fmall between the heat of fummer and winter; it conftantly increases as we advance towards the poles. In general it may be denoted by the formula 5°+25°XI. The coldest season is in the middle of January, the hotteft in July. The monthly variation of temperature is very irregular, and cannot be well afcertained. In general the fummer and winter are pretty uniform, and the greatest variation takes place in the spring and

/ autumn.

out.

But the standard of temperature is variously modified from the nature of the foil, its elevation, its diftance from the ocean, &c. When the air is cloudy it receives heat from the absorption of the folar rays; fometimes it derives a partial warmth from the condensation of vapours; but in general it participates of the temperature of the fubftances with which it is in contact. Water, from its fuperior denfity, absorbs the particles of light, and from its conducting quality becomes equally heated throughThe fuperficial water, as it is heated, becomes specifically lighter and descends. Hence the temperature of lakes does not vary fo much as that of the furrounding atmosphere. When the air was at 81°, the water at the furface of the lake of Geneva was 62o, and at the depth of 87 feet 55o. In feas and in the ocean the variation is still lefs. The gulf of Bothnia differs confiderably from the temperature of the ocean, being fome-. times heated in fummer to 70°, and commonly frozen in winter. The German fea is about 5 degrees warmer in fummer, and 3 degrees colder in winter, than the Atlantic. The Mediterranean is in general warmer than the Atlantic.

Earth receives heat from the fun more readily than water, but conducts it flowly. Befides, the light is spent in heating only the furface of the land, while it is nearly equally diffused through. great bodies of water. In the neighbourhood of Marfeilles the land is often heated to 160°, when the fea is only 77°. In winter the earth is fometimes cooled to 14°, while the fea is 44°.

In

In general, the land is 10° hotter in fummer than the furrounding fea, and as much colder in winter.

The great fource of cold is evaporation. Hence a firm clayey foil, retaining clofely the moisture, does not readily lofe the heat which it has acquired. In ftones or fand, on the contrary, the moisture being extremely divided and diffufed, is quickly evaporated. Hence the intenfe cold of Terra del Fuego. Living vegetables, by their peripiration, prodigioufly affift evaporation. Tall impenetrable forefts, befides excluding the folar rays, are thus the active caufes of cold.. In Guyana in SouthAmerica, that part of the country which was lately cleared, is exceffively hot; while in the wooded parts the inhabitants are obliged to light a fire every night, Cold is increased by every circumftance that promotes the folution of water in the atmosphere; by the heat of the air; by its denfity; by its drynefs, by its motion, &c. Hence the aftoniühing effects of dry winds; as the Sirocco, Harmattan, &c. Lofty mountains are expofed to the aerial motions, and liable to fuffer evaporation; at the fame time that the folar rays, falling obliquely, excite little heat. The fummits of mountains, however, are, from their communication with the mafs of the earth, generally warmer than the air at the. fame altitude; and hence the winds generally tend towards them. As thefe afcend the fides of the mountains, they become rarer, depofit their moifture, and form fog; when they again defcend, they greedily reabforb the moisture from the plains, Hence the effect of mountains in cooling the adjacent country, Even under the equator, and in fummer, the mountains are, at the altitude of 16,000 feet, covered with fnow. This is called the lower point of congelation. No vapour can rife higher than 28,000 feet; and this is termed the highest point of congelation. As we advance to the poles, the curve of perpetual congelation approaches to the furface. In general, if d denote the excess of the annual temperature above 32°, the lower point of congelation will be at the altitude of dX 320 feet, and the higher at dx600. The effect of elevation in reducing the medium temperature, cannot be accurately afcertained. If the afcent be at the rate of fix feet in the mile, of a degree may be allowed for every 200 feet of altitude; if at the rate of 15 feet, half a degree may be allowed. Iflands, participating of the temperature of the furrounding ocean, enjoy a milder climate than continents. The equatorial regions are cooled by the fea breezes ; but the higher latitudes derive additional warmth from the proximity of the ocean.

Our ingenious author proceeds to examine the obfervations that have been made at various places, and to affign the causes which have occafioned the deviations from the ftandard of tem

perature.

perature. The coaft of Africa feems to be the hottest part of the globe. The air in the flade in Senegal is commonly 94°, and in the day time often 111°. In the interior parts of Afia, in Siberia and Grand Tartary, every circumftance contributes to produce intense cold. The land is extremely elevated, at an immense distance from the ocean, and covered with extensive forefts. Hence it is perhaps the chilleft and the most inhofpitable region upon the face of the globe. The temperature of America is in general 10° or 12° below the standard. In fummer the heat is often exceffive, but in winter the moft intense cold is felt. The north-west parts of the continent are lofty, barren, and mountainous; to the eastward are numerous and magnificent lakes, the lower country abounding in fwamps and moraffes, and covered with forefts. Cultivation will therefore contribute, in fome degree, to ameliorate the climate, as well as to improve the scanty foil.

The author concludes with fome remarks upon the causes of unufual cold in Europe: thefe, however, are, in our opinion, vague and indetermined. Our refpect for the philofophicalauthor elevates him much above our verbal criticism. We have given an abftract of his facts and reasonings, and have ventured, in fome inftances, to generalife and extend them. Upon the whole, Mr. Kirwan deferves the highest praise for the industry and ability with which he has treated this new but important subject.

ART. III. Chemical Experiments and Opinions. Extracted from a Work published in the last Century. 8vo. 2s. 6d. Prince, Oxford; Murray, London. 1790.

AF

FTER the progress of science is advanced, we are inclined to pause for a moment, and look back upon the labours of our predeceffors. We are then able to felect the bright ideas which lie buried in the chaos of exploded opinions, and to eftimate their real value and importance. The little jealoufies which disturb the human breaft are foothed into a calm, and we are difpofed, from pure benevolence, to venerate the worth and genius of a past age. The modern discoveries upon the subject of gafes, are fplendid and important; they throw light upon chemistry and phyfiology, and contribute to the convenience and fupport of life. But thefe would appear to us as ftill in their infancy, and the creation of yesterday. We are furprised to find a philofo pher of the laft century purfue the fame tract of investigation, and make several of the fame discoveries. At the fight of the reprefentation of Mayow's pneumatic apparatus annexed to this pamphlet, a certain northern profeffor' (we suppose the cele brated Dr. Black) lifted up his hands in complete aftonifhment.' The name of Mayow is now rescued from oblivion,

and

and muft henceforth be ranked with Bacon and with Boyle. He threw away with fcorn the vague ideas annexed by the old chemifts to the terms fulphur, mercury, &c. He has clearly prefented the notion of phlogifton, which rendered the name of Stahl fo celebrated. He perceived the action of dephlogifticated air in almost all the wide extent of its influence; he was acquainted with the compofition of the atmosphere, and 'contrived to make the mixture of nitrous and atmospherical air. He was well aware of the cause of the increase of weight in the metallic calces, and distinctly asserted that certain bases are rendered acid by the acceffion of nitro-atmospherical particles, or what has fince been denominated the acidifying principle. He discovered the method of producing factitious gas, and obferved its permanent elasticity; and, what is ftill more ftrange, he invented the nice art of transferring it from veffel to veffel. The doctrine of respiration is all his own. He has carried on his investigation of this function from the diminution of the air by the breathing of animals (as well as the burning of bodies) to the change it produces in the blood during its paffage through the lungs, and the use of the placenta.' A genius fo bold, fo fuccefsful, and fo extraordinary, mightily railes our curiofity and gratitude. Dr. Beddoes, with whofe abilities the public is well acquainted from his elegant tranflation of Bergman and Spallanzani, endeavours, in a spirited introduction, to collect fome particulars with regard to the life of Mayow. He was born in 1645, and was admitted a scholar of Wadham College at the age of 16. He had made his principal difcoveries before the age of twenty-three. He fhone bright for a time, but was foon extinguished. He died in an apothecary's houfe near Covent-Garden in 1679, at the age of 34.

This pamphlet contains a tranflation of the contents of Mayow's treatifes, together with an analyfis. We are aftonifhed to obferve the extent and boldness of his inquiries. There is fcarcely a phenomenon in nature which he has not ventured to explain. He feems to have been led into his fpeculations by the confideration of the formation of nitre. This falt derives its alkali from the earth; its acid from the air, and from that portion of the atmosphere which he terms fire-air or nitroatmospherical. The motion of thefe aerial particles occafions combuftion. Hence the deflagration of nitre, and the current of air directed to burning bodies. He conceives that the alkali found in the afhes of vegetables arises from the decompofition of the nitre which they contained. The nitro-atmospherical particles pafs into the blood during refpiration, and communicate warmth and the florid colour. He imagines that the umbilical

an egg.

umbilical arteries carry to the foetus, not only the nutricious juice, but also nitro-aerial particles, and thus fupplies the want of refpiration. The fame remark he extends to chicken of We must observe, however, that Mayow is ftrongly tinctured with the prejudices of his age. Like a fanguine theorift, he fondly imagines that his nitro-aerial principle is the grand mover in nature. He applies it to the explanation of folidity and elasticity; to that of the phenomena of water-fpouts, thunder, and light, and colours. A lucid idea occafionally bursts out of a crowd of wild and extravagant notions, and it requires an attention to the late discoveries to appreciate his true merit.

We cannot conclude without mentioning an important experiment which Dr. Beddoes flightly announces. Nitrous acid has been procured by tranfmitting dephlogisticated air from Manganese along with atmospherical through a heated tube.

ART. IV. On the Confideration due to the Clergy from their Importance in Society; a Sermon preached at the Anniversary Meeting of the Sons of the Clergy of Pembrokeshire, on Tuesday June 20, 1789, in the Parish Church of St. Mary, Haverfordwest. By Charles Symmonds, B D. Rector of Narbeth. Printed for the Charity, by Rofs of Carmarthen. 4to. Is. Williams, London. 1790.

IN N this elegant compofition the reverend author, after shewing the different ranks neceffary in a state of civil fociety, and how much the existence of all depends on the due fupport of each, enters into an inquiry in what rank the priesthood should be held. In doing this, he prefents us with an historical deduction of the facred character, from the earliest ages to the state in which we now fee it.

In the first ages,' obferves our author, the facred was infeparable from the royal character, the patriarch was the priest < as well as king.' This leads him to defcribe the honorary 'diftinction conferred by God himself on the order, which continued as long as the Jewish difpenfation lafted. When this gave way to an improved fyftem, the condition of the priesthood was only apparently changed. With its fplendid trappings it lost no part of its dignity. Though he refufed his direct fanction to any particular form of church government, the bleffed Founder of our religion fuggefted the establishment of a priesthood, of different degrees, by his firft delegation of the twelve, and by his fubfequent one of the feventy difciples.

Our author gives next a very beautiful defcription of the fimplicity obfervable in the early ages of the Christian church,

dignified