Hot and Thermal Springs. 39S 



The lowest temperatures of sea-water in great depths were ob- 

 served by Irvine and Horner. On the 20th of June, the for- 

 mer found a temperature of 27°.5 at a depth of 3900 feet, in 67° 

 N. Lat. ; and the latter observed a temperature of 28°.4 in the 

 Sea of Ochotzk between 30 and 115 fathoms deep. Horner 

 conjectures that this degree is the limit below which the tempe- 

 rature of the sea never falls. 



These temperatures are, then, still 2°.25 or 3M50 higher than 

 25°.2. From which the same consequence may be deduced 

 which was concluded from the above observations in the Swiss 

 Lakes, namely, that the water of the sea and of laJces must re- 

 ceive heat from the earth beneath. The heat which the sea re- 

 ceives from its- bottom depends, as in lakes, on the latitude, and 

 the depth of the water. If the depth of the sea at the equator 

 were only 6658 feet, and supposing the temperature of the 

 earth there to increase with the depth in the same proportion as 

 in the sounding near the Lake of Geneva.^ the temperature of 

 the bottom of the sea would there reach the boiling point ; but 

 as the actual temperature at the bottom of the sea at its great- 

 est depths in low latitude, according to Lenz, is 35°.96, we 

 have 212° — 3°.96=208°.04< for the thermometrical expression 

 of the heat which is communicated from the bottom of the 

 sea to the water, and with it brought to the surface.. The po- 

 sitive quantity of heat thus brought to the surface obviously 

 depends, as is the case in lakes, on the degree of conductibility 

 of heat of the strata beneath. As the sea in the torrid zone is 

 very commonly far deeper than the above assumed depth of 

 6658 feet, there must be many places in those regions where the 

 temperature corresponding to the bottom of the sea would be 

 much higher than the boiling point. But, even in the frigid 

 zones, where the niean temperature falls as low as, and even 

 lower, than 32\ much heat may still rise from the bottom of the 

 sea even in moderate depths. The rising of heat from the bot- 

 tom of the sea may, therefore, be considered as an universal 

 phenomenon, even under the poles, and it will only be found 

 not to take place where the sea in the frigid zones is so shallow, 

 that there is no perceptible difference between the temperature 

 of its bottom and ol' its surface. 



