144 DISCUSSIONS IN CLIMATOLOGY. 



greater than that indicated by the ratio 12 to 5. But, 

 assuming 12 to 5 to be the ratio, the question arose 

 what ought to be the difference of temperature between 

 the two places in question on the supposition that the 

 temperature was due solely to the direct heat received 

 from the sun ? This was a question difficult to answer, 

 for its answer mainly depended upon two con- 

 siderations, regarding both of which a very consider- 

 able amount of uncertainty prevailed. 



First, it was necessary to know how much of the 

 total amount of heat received by the earth was derived 

 from the sun, and how much from the stars and other 

 sources, or, in other words, from space. Absolute zero 

 is considered to be —461° Fahr. The temperature 

 of the equator is about 80°. This gives 541° Fahr. 

 as the absolute temperature of the equator. Now, were 

 all the heat received by the earth derived simply from 

 the sun, and were the temperature of each place pro- 

 portionate to the amount directly received, then the 

 absolute temperature of the poles would be ^ of that 

 of the equator, or 225°. This would give a difference 

 of 316° between the temperature of the equator and 

 that of the poles. According to Pouillet and Herschel, 

 space has a temperature of — 239°, or 222° of absolute 

 temperature. If this be the temperature of space, 

 then only 319° of the absolute temperature of the 

 equator are derived from the sun; consequently, as 

 the poles receive from the sun only T % of this amount 

 of temperature, or 133°, this will give merely 186° as 

 the difference which ought to exist between the 

 equator and the poles. There is, however, good 

 reason for believing that the temperature of space 

 is far less than that assigned by Pouillet and Herschel 

 — that, in fact, it is probably not far above absolute 

 zero. Therefore, by adopting so high a temperature 



