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no heat to the water below. Indeed it can be proved by experi- 

 ment^ that water does not transmit heat downwards by conduc- 

 tion ; whereas, in applying heat underneath instead of to the sur- 

 face, it is easily transmitted. Had the globe contained an igne- 

 ous nucleus, whatever might be the bad conducting quality of 

 the crystalline shell, it would be heated, and that heat would be 

 communicated to the ocean, and an ebullition would be produced 

 sufficiently strong, if not to cause evaporation of the ocean, 

 at least to prevent the formation of ice at the poles, and the 

 heat would increase as we descend. The observed facts are 

 quite the reverse. It is very probable that the ocean at a cer- 

 tain depth possesses a constant temperature, and according to 

 observations made in the polar regions on the temperature of the 

 ocean under the ice at the depth of 100 fathoms, we may con- 

 sider it about 45° Fahr. We may appeal to observations for 

 proof that it is at the surface of the globe the greatest variations 

 of temperature take place, and from this surface they diminish 

 as we ascend into the air or descend into the ocean, till in each 

 direction they terminate at an invariable temperature, where 

 the solar radiant heat becomes insensible ; and it is within these 

 zones of variable temperature that the animal and vegetable 

 kingdoms are bounded. 



According to the above, we find that in sailing from the south 

 pole to the north we are exposed to zones of variable tempera- 

 ture : commencing at 32° Fahr., and on arriving at the equator, 

 it amounts to 84°*2. and becomes reduced again as we approach 

 the north pole to 32°. If, instead of sailing on the ocean, we sail 

 through the air at the elevation of the above curve, we should 

 be constantly exposed to the low temperature of 32°. The vari- 

 able height of the land between the level of the sea and the curve 

 of congelation must therefore vary the climate of the different 

 zones, independent of their latitudes. Within the tropics we 

 may obtain any temperature from 84°*2 to 32°, by regulating our 

 elevation ; but in the frigid zone we are limited for the want of 

 direct rays, and cannot obtain a mean temperature above 50° by 

 depression, or by any other means we may choose to adopt; 

 consequently no changes in the relative position of land and sea 

 can produce a tropical climate in the polar zone. The aspect of 

 a country has an influence upon its climate, for this reason, that 

 the angle at which the suit's rays strike the ground, and conse- 



