ture observed in Wolstenholme Sound, in the winter of 1850;' and Sir John Richardson2 noted it at Fort Confidence in 66° 54′ N. L., and 118° 49′ W. L., at —65° in the winter of 1848-9. The extremes of cold experienced by Captain McClure and his party at Mercy Bay in Jan. and Feb., 1855, were 62° and -65°. În the Arctic expedition of 1853-4, under the command of Dr. Kane, the range of eleven spirit thermometers, selected as standards, varied from -60° to -75o. The mean annual temperature was 5°.2:-the lowest ever registered. Captain Back, in his expedition to the Arctic regions of this continent, on the 17th of January, 1834, noticed the thermometer at -70° of Fahrenheit. Mr. Erman states, that at Yakutsk it was at -72.5 of Fahrenheit; and Sir George Simpson' affirms, that it has fallen in Siberia to -83° or 115° below the freezing point, which-if the thermometers could be depended upon-may be regarded as the greatest depression observed in any climate. The great variation, however, even in spirit instruments selected as standards, at these very depressed temperatures as observed by Dr. Kane, throws doubts as to the actual temperature unless taken by different thermometers. During the second voyage of Captain Parry," the following tempe ratures of animals, immediately after death, were taken principally by Captain Lyon. 1821. Nov. 15. An Arctic fox Temperature of the Animal. Atmosphere. These animals must, therefore, have to maintain a temperature at least 100° higher than that of the atmosphere throughout the whole of winter; and it would seem as if the counteracting energy becomes proportionately greater as the temperature is more depressed. It is, Journal of a Voyage in Baffin's Bay and Barrow's Straits in the years 1850-1851, performed by H. M. Ships Lady Franklin and Sophia, under the command of Mr. William Penny, &c. &c., By Peter C. Sutherland, M. D., &c., i. 285, London, 1852. 2 Arctic Searching Expedition: a Journal of a Boat's Voyage through Rupert's Land and the Arctic Sea, in search of the discovery ships under command of Sir John Franklin, ii. 102, London, 1851. 3 Narrative of the Arctic Land Expedition to the mouth of the Great Fish River, &c., in the years 1833, 1834, and 1835, London, 1836. 1848. Travels in Siberia, translated from the German, by W. D. Cooley, ii. 369, London, An Overland Journey round the World, Amer. edit., part ii. p. 134, Philad., 1847. Op. citat., p. 157. however, a part of their nature to be constantly eliciting this unusual quantity of caloric, and therefore they do not suffer. Where animals, not so accustomed, are placed in an unusually cold medium, the efforts of the system rapidly exhaust the nervous energy; and when this is so far depressed as to interfere materially with the function of calorification, the temperature sinks, and the sufferer dies lethargic-or as if struck with apoplexy. The ship Endeavour, being on the coast of Terra del Fuego, on the 21st of December, 1769, Messrs. Banks, Solander, and others were desirous of making a botanical excursion on the hills on the coast, which did not appear to be far distant. The party, consisting of eleven persons, were overtaken by night, during extreme cold. Dr. Solander, who had crossed the mountains which divide Sweden from Norway, knowing the almost irresistible desire. for sleep produced by exposure to great cold, more especially when united with fatigue, enjoined his companions to keep moving, whatever pains it might cost them, and whatever might be the relief promised by an indulgence in rest. "Whoever sits down," said he, "will sleep, and whoever sleeps will wake no more." Thus admonished, they set forward, but whilst still upon the bare rock, and before they had got among the bushes, the cold suddenly became so severe as to produce the effects that had been dreaded. Dr. Solander himself was the first who found the desire irresistible, and insisted on being suffered to lie down. Mr. Banks (afterwards Sir Joseph) entreated and remonstrated in vain. The doctor lay down upon the ground, although it was covered with snow; and it was with the greatest difficulty that his friend could keep him from sleeping. Richmond, one of the black servants, began to linger and to suffer from the cold, in the same manner as Dr. Solander. Mr. Banks, therefore, sent five of the company forward to get a fire ready at the first convenient place they came to; and himself, with four others, remained with the Doctor and Richmond, whom, partly by persuasion and partly by force, they carried forward; but when they had got through the birch and swamp, they both declared they could go no farther. Mr. Banks had again recourse to entreaty and expostulation, but without effect. When Richmond was told, that if he did not go on, he would, in a short time, be frozen to death, he answered, that he desired nothing but to lie down and die. Dr. Solander was not so obstinate, but was willing to go on, if they would first allow him to take some sleep, although he had before observed, that to sleep was to perish. Mr. Banks and the rest of the party found it impossible to carry them, and they were consequently suffered to sit down, being partly supported by the bushes, and, in a few minutes, they fell into a profound sleep. Soon after, some of the people, who had been sent. forward, returned with the welcome intelligence, that a fire had been kindled about a quarter of a mile farther on the way. Mr. Banks then endeavoured to rouse Dr. Solander, and happily succeeded; but, although he had not slept five minutes, he had almost lost the use of his limbs, and the soft parts were so shrunk, that his shoes fell from his feet. He consented to go forward with such assistance as could be given him; but no attempts to relieve Richmond were successful. He, with another black left with him, died. Several others began to VOL. I.-38 lose their sensibility, having been exposed to the cold near an hour and a half, but the fire recovered them. The preceding history is interesting in another point of view be sides the one for which it was more especially narrated. Both the individuals, who perished, were blacks; and it has been a common observation, that they bear exposure to great heat with more impu nity, and suffer more from intense cold, than the white variety of the species. As regards inorganic bodies, it has been satisfactorily shown, that the phenomena of the radiation of caloric are connected with the nature of the radiating surface; and that those surfaces, which radiate most, possess, in the highest degree, the absorbing power; in other words, bodies that have their temperatures most readily raised by radiant heat are those that are most easily cooled by their own radiation. In the experiments of Professor Leslie' it was found, that a clean metallic surface produced an effect upon the thermometer equal to 12; but when covered with a thin coat of glue its radiating power was so far increased as to produce one equal to 80; and, on covering it with lampblack, it became equal to 100. We can thus understand why, in the negro, there should be a greater expense of caloric than in the white, owing to the greater radiation; not because as much caloric may not have been elicited as in the white. In the same manner we can comprehend, that, owing to the greater absorbing power of his skin, he may suffer less from excessive heat. To ascertain, whether such be the fact, the following experiments were instituted by Sir Everard Home. He exposed the back of his hand to the sun at twelve o'clock, with a thermometer attached to it, another being placed upon a table with the same exposure. The temperature, indicated by that on his hand, was 90°; by the other, 102°. In forty-five minutes, blisters arose, and coagulable lymph was thrown out. The pain was very severe. In a second experiment, he exposed his face, eyelids, and the back of his hand to water heated to 120°; in a few minutes they became painful; and, when the heat was farther increased, he was unable to bear it; but no blisters were produced. In a third experiment, he exposed the backs of both hands, with a thermometer upon each, to the sun's rays. The one hand was uncovered: the other had a covering of black cloth, under which the ball of the thermometer was placed. After ten minutes, the degree of heat of each thermometer was marked, and the appearance of the skin examined. This was repeated at three different times. The first time, the thermometer under the cloth stood at 91°; the other at 85°; the second time, they indicated respectively 94° and 91°; and the third time, 106° and 98°. In every one of these trials, the skin that was uncovered was scorched; whilst the other had not suffered in the slightest degree. From all his experiments, Sir Everard concludes, that the power of the sun's rays to scorch the skin of animals is destroyed, when applied to a black surface; although the absolute heat, in consequence of the absorption of the rays, is greater. When cold is applied to particular parts of the body, their heat 1 On Heat, Lond., 1788; and Dr. Stark, in Philosoph. Transact., part ii. for 1833. 2 Lect. on Comp. Anat., iii. 217, London, 1823. sinks lower than the minimum of depressed temperature. Although Mr. Hunter was unable to heat the urethra one degree above the maximum of elevated temperature of the body, he succeeded in cooling it 29° lower than the minimum of depressed temperature, or to 58°. He cooled down the ears of rabbits until they froze; and when thawed they recovered their natural heat and circulation. The same experiment was performed on the comb and wattles of a cock. Resuscitation was, however, in no instance practicable where the whole body had been frozen. The same distinguished observer found, that the power of generating heat, when exposed to a cooling influence, was possessed even by the egg. One, that had been frozen and thawed, was put into a cold mixture along with one newly laid. The latter was seven minutes and a half longer in freezing than the former. In another experiment, a fresh-laid egg, and one that had been frozen and thawed, were put into a cold mixture at 15°; the thawed one soon rose to 32°, and began to swell and congeal the fresh one sank to 2910, and in twenty-five minutes after the dead one, rose to 32°, and began to swell and freeze. All these facts prove, that when the living body is exposed to a lower temperature than usual, a counteracting power of calorification exists; but that, in the human species, such exposure to cold is incapable of depressing the temperature of the system lower than about 15° beneath the natural standard. In fish, the vital principle can survive the action even of frost. Captain Franklin found, that those which they caught in Winter Lake, froze as they were taken out of the net; but if, in this completely frozen condition, they were thawed before the fire, they recovered their animation. This was especially the case with a carp, which recovered so far as to leap about with some vigour after it had been frozen for thirty-six hours. On the other hand, when the living body is exposed to a temperature greatly above the natural standard, an action of refrigeration is exerted; so that the animal heat cannot rise beyond a certain number of degrees; -to a much smaller extent in fact than it is capable of being depressed by the opposite influence. Boerhaave maintained the strange opinion, that no warm-blooded animal could exist in a temperature higher than that of its own body. In some parts of Virginia, there are days in every summer, in which the thermometer reaches 98° of Fahrenheit; and in other parts of this country it is occasionally much higher. The meteorological registers show it to be, at times, at 108° at Council Bluffs, in Missouri; at 104° in New York; and at 100° in Michigan;3 whilst in most of the states, in some days of summer, it reaches 96° or 98°. ` At Sierra Leone, Messrs. Watt and Winterbottom saw it frequently at 100°, and even as high as 102° and 103°, at some distance from the coast. Adanson observed it at Senegal as high as 10810. Sir John Sir E. Home's Lect., &c., iii. 438. 2 "Observatio docet nullum animal quod pulmones habet posse in aere vivere, cujus eadem est temperies cum suo sanguine." Element. Chemiæ, i. 275, Lug. Bat., 1732. 3 Meteorological Register, for the years 1822, 1823, 1824, and 1825, from observations made by the surgeons at the military posts of the United States. See, also, a similar register for the years 1826, 1827, 1828, 1829, and 1830, Philad., 1840; and another from 1843 to 1854, inclusive, Washington, 1855. Account of the Native Africans, vol. i. pp. 32 and 33. Barrow,' at the village of Graaf Reynet, in South Africa, noted it on the 24th of November, at 108° in the shade and open air. Brydone affirms, that when the sirocco blows in Sicily the heat rises to 112° Dr. Chalmers observed a heat of 115°3 in South Carolina; Humboldt of 110° to 115° in the Llanos or Plains near the Orinoco; and Captain Tuckey asserts, that on the Red Sea he never saw the thermometer at midnight under 94°; at sunrise under 104°; or at midday under 112°. In British India it has been seen as high as 130°.5 As long ago as 1758, Governor Ellis' of Georgia had noticed how little the heat of the body is influenced by that of the external atmosphere. "I have frequently," he remarks, "walked an hundred yards under an umbrella with a thermometer suspended from it by a thread, to the height of my nostrils, when the mercury has rose to 105°, which is prodigious. At the same time I have confined this instrument close to the hottest part of my body, and have been astonished to observe, that it has subsided several degrees. Indeed I could never raise the mercury above 97° with the heat of my body." Two years after the date of this communication, the power of resisting a much higher atmospheric temperature was discovered by accident. MM. Duhamel and Tillet," in some experiments for destroying an insect, that infested the grain of the neighbourhood in Augoumois,-having occasion to use a large public oven, on the same day in which bread had been baked in it, were desirous of ascertaining its temperature. This they endeavoured to accomplish by introducing a thermometer into the oven at the end of a shovel. On being withdrawn, the thermometer indicated a degree of heat considerably above that of boiling water; but M. Tillet, feeling satisfied, that the thermometer had fallen several degrees in approaching the mouth of the oven, and seeming to be at a loss how to rectify the error, a girl,-one of the servants of the baker, and an attendant on the oven,-offered to enter and mark with a pencil the height at which the thermometer stood within. She smiled at M. Tillet's hesitation in accepting her proposition; entered the oven, and noted the temperature to be 260° of Fahrenheit. M. Tillet, anxious for her safety, called upon her to come out; but she assured him she felt no inconvenience, and remained ten minutes longer, when the thermometer had risen to 280° and upwards. She then came out of the oven, with her face considerably flushed, but her respiration by no means quick or laborious. These facts excited considerable interest; but no farther experiments appear to have been instituted, until, in the year 1774, Dr. Geo. Fordyce, and Sir Charles Blagden made their celebrated trials with heated air. The rooms, in which these were made, were heated by flues in the floor. Having taken off his coat, waistcoat, and shirt, and being Auto-biographical Memoir, p. 193, London, 1847. 2 Lawrence's Lectures on Comparative Anatomy, Physiology, &c., p. 306, London, 1819. 3 Account of the Weather and Diseases of South Carolina, London, 1776. Tableau Physique des Regions Equatoriales. 6 Prof. Jameson, British India, Amer. edit., iii. 170, New York, 1832. Philosophical Transactions, 1758, p. 755. 7 Mémoir. de l'Académie des Sciences, p. 186, Paris, 1762. & Philosophical Transactions for 1775, p. 111. |