478 THE ICE AGE IN NORTH AMERICA, 



upon the action of forces whose laws can not now be accurately 

 calculated. As Woeikoif goes on to show, there are some very 

 singular facts in the distribution of heat over the earth's sur- 

 face — proving that the equator is not so hot as theoretically 

 it ought to be, and that the arctic regions are not so cold ; and 

 this in places which could not be affected by oceanic currents. 

 For example, at Iquitos, on the Amazon, only three hundred 

 feet above tide, three degrees and a half south of the equator, 

 and more than a thousand miles from the Atlantic (so that 

 ocean-currents can not abstract the heat from its vicinity), 

 the mean yearly temperature is but 78° Fahr., while at 

 Verkhojansk, in northeast Siberia, which is 67° north of the 

 equator, and is situated where it is out of the reach of ocean- 

 currents, and where the conditions for the radiation of heat 

 are most favorable, and where, indeed, the winter is the 

 coldest on the globe (January averaging —56° Fahr.) the 

 mean yearly temperature is two degrees and a half above zero ; 

 so that the difference between the temperature upon the 

 equator and that at the coldest point on the sixty-seventh 

 parallel is only about 75° Fahr. ; whereas, if temperature were 

 in proportion to heat received from the sun, the difference 

 ought to be 172°. Again, the difference between the actual 

 January temperature on the fiftieth parallel and that upon 

 the sixtieth is but 20° Fahr., whereas, the quantity of solar 

 heat received on the fiftieth parallel during the month of 

 January is three times that received upon the sixtieth, and 

 the difference in temperature ought to be about 170° Fahr. 

 upon any known law in the case. 



But to be quite sure to get beyond the influence of ocean- 

 currents, I will take the mean January temperature in the 

 strictly continental climate of eastern Siberia, under 120° east 

 According to Ferrel's tables : 



Under 50° north we have 0° Fahr. 

 Under 60° north we have —30° Fahr. 

 If the January temperature decreased from 50° to 60° north, 

 according to the hypothesis of Dr. Croll, it should be on the 

 60° north -155° Fahr. 



