TEMPERATURE. 



equator, or the poles, a greater depth would be necefTary to 

 obtain the permanent temperature. At ftill greater depths, 

 probably, the temperature under each degree of latitude is 

 the fame all over the globe, except in the vicinity of vol- 

 canic fires. 



M. Volney, in his travels through North America, fpeak- 

 ing of the temperature of the earth, endeavours to oppofc 

 the opinion ol its permanent internal temperature. Setting 

 out from la.ke Superior, he fays, and proceeding weft to 

 the Stoney mountains, and travelling north as far as latitude 

 72°, the country now well known to the Canadian traveller, 

 difplays a climate that for feverity of cold can be compared 

 only to Siberia. From latitude 46", the earth is frozen 

 during the whole year. At fevcral trading pods between 

 latitude 50" and 56°, it was found impofiiblc to have wells. 

 Mr. Shaw had attempted to dig one at the poft of St. Au- 

 guftin, about forty miles from the mountains ; but though 

 it was in the month of July, the ground was frozen at the 

 depth of three feet from the furface, and as it grew harder 

 he was obliged to give up the attempt. He relates alfo 

 an account of Mr. Robfon, an Englilh engineer, who at- 

 tempted to fmk a well at Prince of Wales's fort, lati- 

 tude 59°, in the month of September. He firll found 

 thirty-fix inches of earth thawed by the preceding warin 

 weather, then a ftratum of eight inches frozen as hard as a 

 ftone ; under this a flratum of fandy friable earth, froily 

 and very dry, in which his borer could find no water. The 

 celebrated traveller Ledyard, fays Volney, affirms, that at 

 Yakutllc, not io high as latitude 62°, wells of water 

 cannot be obtained, becaufe it is found by experiment that 

 water freezes at the depth of fixty feet. From thefe cir- 

 cumftances, M. Volney would infer that the internal part of 

 the earth is in a conftant ftate of congelation. Some of the 

 above obfervations, we believe, were inaccurately made ; 

 and it has been too haftily determined, that the earth 

 is frozen during the whole year in Nortli America, even 

 in latitude 46°; for this is not the cafe 11° further 

 north. We have been favoured with the following ftate- 

 ment from an intelligent medical gentleman, who was iome 

 years refident in Hudfon's Bay. " On digging a well at 

 York fort, Hudfon's Bay, latitude 57° 7', in the beginning 

 of Oftober, the following circumftances were remarked. 

 About thirty inches from the furface, a bed of frozen earth, 

 about twilve inches thick, was met willi ; below was a bed 

 of loofe fandy clay, about half a yard thick, which was fuc- 

 ceeded by a bed of the fame clay, rendered perfeftly hard 

 and folid by troft. Sinking lower, ilmilar beds of frozen 

 and loofe earth were found, alternating with each other ; the 

 frozen beds, however, conftantly decreafing in tliicknefs, 

 though not regularly, and at a certain depth they feemed to 

 difappear entirely. Thefe frozen ftrata are confidered by 

 the inhabitants as indications of the feverity of the preceding 

 winters, each ftratum being fuppofed, with much proba- 

 bihty, to be formed in different years, and to be travelling 

 downward until they are thawed by the internal temperature 

 of the earth. The procefs by which they fink down may 

 be explained, on the fuppofition that the upper furface is 

 diminiftiing by heat during iummer, and the under furface 

 increafing by the congelation of moifture in contaft with it. 

 Another circumftance, wliich took place in the fame latitude, 

 may ferve to elucidate the obfervation of Ledyard, that 

 the water was conftantly frozen at fixty feet under the fur- 

 face at Yakutflc." A well had been funk which yielded a 

 plentiful fnpply of water during the firft fummer ; but the 

 water, being expofed to the air, froze during the next 

 winter, and remained frozen ever after, being too far below 

 the furfEce to be thawed. Hence it appears that water 



cxifts unfrozen at a moderate depth under the furface in the 

 coldeft climates, when it has no communication with the 

 external air. The cffcA of the fummer heat in the fame 

 latitude extends about feventcen inches under tlie furface, 

 where the ground has been ftiadcd ; hut where it has 

 been expofed to the fun, the furface is thawed to the 

 depth of tiirec feet. From the fmall deptli to which the 

 folar heat penetrates, we may infer that l!ie water below 

 is kept in a fluid ftate by the internal lirat of the globe. 

 It has been generally fuppofed, that the permaiu'nt tem- 

 perature of each latitude is the fame nearly as the n-.eau 

 annual temperature of the atmofphere, and that ihis is 

 indicated by the temperature of fprings or deep wells ; but 

 the temperature of fprings will vary with that of the ftrata 

 near the furface through which they run.. (Sec TtM- 

 PERATURE of springs.) It is to be regretted that more 

 numerous obfervations have not been made on the tempe- 

 rature of deep mines. From obfervations recently made in 

 Cornwall, it appears that tlie temperature increafes with the 

 depth, at leaft in lomc of the mines, and in the loweft it was 

 not lefs than 70°. This may, perhaps, be owing to the che- 

 mical changes which are taking place ; for it appc ars, from the 

 evidence of the overfeers of the mines, in reply to' certain 

 ([ueries propofed by the Royal Geological Society of Corn- 

 wall, that the water is found conftantly warmer in the 

 vicinity of veins of copper-ore, than it is in the vicinity, of 

 tin-ore : the former veins are in general worked to a greater 

 depth tlian the latter. It remains to be afccrtained wliether 

 this incrcafe of temperature be owing to chemical caufes, or 

 is invariable at the fame diftance from the furface. Tiie 

 decompofition of pyrites in copper veins would feem to point 

 out a caufe for the increafed temperature in their vicinity ; 

 it is evident, however, that it is not derived from the folar 

 rays. It fecms reafonable to believe, from what we at prc- 

 fcnt know of the internal temperature of the eartli, that 

 there exifts a permanent fource of heat within the globe, 

 though we are unacquainted with the caufes by which it 

 is generated. We are equally ignorant of the caufes by 

 which light is generated on the furface of the fun : oriC 

 operation is not more furprifing or inexplicable than the 

 other ; nor is the difficulty removed, by fuppofing the fun 

 to be furrounded with a luminous atniofphere. Some 

 philofophers have maintained the opinion, that the earth has 

 been conftantly growing colder fince the period when it was 

 firft inhabited, and that the organic remains of elephants and 

 other animals, (fuppofed to be fimilar to thofe of tropical 

 climates,) which are found in Siberia, offer a demonftrative 

 proof, that the arftic regions once enjoyed the _ tempe- 

 rature of the torrid zone. It has fince been afcertained, 

 by the elaborate refearches of M. Cuvier, that thefe animals 

 were not of the fame fpecies as the African or Afiatic 

 elephant. A moft convincing proof of this was afforded 

 by the entire body of one of thefe elephants, which was 

 difcovered imbedded in ice near the mouth of a river in the 

 north of Siberia, by a Tungnfian fiftierman, in the year 

 1799. It firft prefented a ftiapelcfs mafs projt fling from 

 an ice -bank. Two years afterwards he could diftir.clly fee 

 that it was the body of an enormous animal ; tlie entire 

 flank and one of its tuflis had become difengaged from the 

 ice. In 1803, the ice beginning to melt earHer than ufual, 

 the whole body was difengaged, and fell from the ice-bank 

 on the fandy (liore. In 1806, Mr. Adams went to examine 

 this animal, which ftill remained on the fand, but its body 

 was much mutilated. The flcin was extremely thick and 

 heavy, and as much of it remained as required the exertions 

 of ten men to carrj' away. More than thirty pounds of 

 the hair and briftlcs of the animal were colkfted. Some of 



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