482 Proceedings. 



We thus see that Croll's argument is based on two facts, which he 



considers placed beyond all doubt — that winds are the impelling cause of ocean 

 currents, and that the ocean currents are the great agents employed in 

 distributing over the globe the excess of heat received by the sea in intertropical 



regions. 



The majestic flow of waters from the Gulf of Mexico— that "mighty 



t — equals 



an 



conveys a quantity of heat equal — to use the philosophic slang of the day — to 

 77,479,650,000,000,000,000 foot-pounds. That he has not overestimated 



>wn 



important results obtained during the " Challenger" expedition. Between 

 Bermuda and Sandy Hook the stream is sixty miles broad and 600 feet deep, 



maximum 



observations made between St. Thomas and Sandv Hook 



existence 



of an immense flow of warm water 2300 feet deep, coming 



At Sandy Hook 



Mexico 



it extends 1200 feet deeper than the Gulf Stream itself. Thismass of water, 



miles 



direction of the Azores, where it appears to thin out. 



Croll then goes on to argue that any cause which will greatly affect the 

 currents, or greatly change their paths and mode of distribution, will of 

 necessity greatly affect the climatic condition of the globe. But, as the 

 existence of these currents depends on the winds, any cause which will greatly 

 affect the winds will also greatly affect the currents, and consequently will 

 influence the climatic conditions of the globe. Again, as the existence of the 

 winds depends mainly on the difference of temperature between equatorial 

 and polar regions, any cause which will greatly affect this difference of 



temperatur 



That is, should any cause 



increase the difference of temperature between the equator and the pole on the 

 one hemisphere, and decrease that difference on the other hemisphere, it 

 would effect a change in the distribution of the aerial currents, which change 



turn produce a correspondin 



currents 



Now, an increase in the eccentricity of the earth's orbit tends to lower the 

 temperature of one hemisphere and to raise the temperature of the other. Let 

 us imagine the eccentricity at its superior limit to be -07775, and the winter 

 solstice of the northern hemisphere, instead of in perihdio as at present, to be 

 in aphelio. The midwinter temperature, owing to the increased distance of 

 the sun, would be lowered enormously; and the effect of this would be to 

 cause all the moisture which now falls as rain during winter in temperate 



