536 EVOLUTION OF HEAT, LIGHT, AND ELECTRICITY. 



have within themselves the power of compensating for these, in a very ex- 

 traordinary degree. The power seems to exist in Man to a higher amount 

 than in most other animals; since he cannot only support, but enjoy life, 

 under extremes of which either would be fatal to many. In many parts of 

 the tropical zone, the thermometer rises every day, through a large portion 

 of the year, to 110 ; and in British India it is said to be seen occasionally 

 at 130. On the other hand, the degree of cold frequently sustained by 

 Arctic voyagers, and quite endurable under proper precautions, appears much 

 more astonishing; by Captain Parry the thermometer has been seen as low 

 as 55, or 87 below the freezing-point ; by Captain Franklin at 58, or 

 90 below the freezing-point; and by Captain Back at 70, or 102 below 

 the freezing-point. In both cases, the effect of the atmospheric temperature 

 on the body is greatly influenced by the condition of the air as to motion or 

 rest : thus, every one has heard of the almost unbearable oppressiveness of 

 the "sirocco," or hot wind of Sicily and Italy, the actual temperature of 

 which is not higher than has often been experienced without any great dis- 

 comfort when the air is calm ; and on the other side, it may be mentioned 

 that, in the experience of many Arctic voyagers, a temperature of -50 

 may be sustained, when the air is perfectly still, with less inconvenience 

 than is caused by air in motion at a temperature fifty degrees higher. 1 This 

 is quite conformable to what might be anticipated on physical principles. 



428. Again, the degree of moisture contained in a heated atmosphere, 

 makes a great difference in the degree of elevation of temperature which 

 may be sustained without inconvenience. Many instances are on record, of 

 a heat of from 250 to 280 being endured in dry air for a considerable 

 length of time, even by persons unaccustomed to a particularly high tem- 

 perature; and persons whose occupations are such as to require it, can sus- 

 tain a much higher degree of heat, though riot perhaps for any long period. 

 The workmen of the late Sir F. Chantrey were accustomed to enter a furnace 

 in which his moulds were dried, whilst the floor was red-hot, and a ther- 

 mometer in the air stood at 350 ; and Chabert the "Fire King" was in the 

 habit of entering an oven the temperature of which was from 400 to 600 . 2 

 It is possible that these feats might be easily matched by many workmen 

 who are habitually exposed to high temperatures ; such as those employed 

 in Iron-foundries, Glass-houses, and Gas-works. In all these instances, the 

 drynessof the air facilitates the rapid vaporization of the fluid whose secre- 

 tion by the Cutaneous glandular is promoted by heat applied to the surface ; 



1 The Author has been informed by Sir John Richardson, that in his last Arctic 

 Expedition, whilst at winter quarters, he was accustomed to go from his sitting-room 

 to the magnetic observatory at a short distance (about an ordinary street's breadth), 

 without feeling it necessary even to put on a great coat; although the temperature 

 of the former was about 50, and that of the air through which he had to pass to the 

 latter was 50, the difference being 100. This immunity from chilling influence 

 was chiefly attributable to the dryness and stillnc.fss of the atmosphere; but it is 

 worthy of note that Sir J. Kichardson and the whole of his party on this expedition 

 abstained entirely from alcoholic liquors; and the Author has received his personal 

 assurance, that his experience on this occasion fully bore out his previous conviction, 

 that continued severe cold is inur.h better borne without recourse to these stimulants, 

 than under the employment of them. 



1 The wonderful feats performed by many individuals from time to time of dip- 

 ping the hand into melted lead, laying hold of a red-hot iron, etc. have been re- 

 cently shown by M. de B"Utigny to be explicable upon very simple principles. For 

 in all such cases a thin film of aqueous fluid in the "spheroidal state " intervenes 

 between the skin and the heated surface; and a hand which is naturally damp, 

 or which lias been slightly moistened, may be safely passed into the stream of molten 

 iron as it llnws from the furnace; as was demonstrated byM.de Boutigny at the 

 meeting of the British Association at Ipswich in 1851. 



