390 Searles 7. Woody Jun. — The Climate Controversy. ■ 



the snowclad condition of Sandwich Land and the South Georgian 

 Isles — lying in latitudes corresponding, respectively, to the North 

 of Scotland and centre of England — is due. In reference, however, 

 to the interception and absorption of the sun's rays by the creation 

 of fogs, are we not entitled to assume that, since vapours give out 

 in condensation an amount of heat equal to that absorbed in their 

 creation, compensation would be thus afforded, and all the heat 

 intercepted by fogs be eventually restored to the atmosphere of the 

 icy region ? 



To argue that cold produces ice and snow, and that these again 

 aggravate the cold, and so, by reacting on the cause, tend to produce 

 a continual accumulation of the effect, does to many minds seem 

 arguing in a circle. This Mr. Croll admits, but contends that the 

 argument is none the less sound. He does not, however, pursue 

 his argument to that extent which carries conviction to my mind, 

 but leaves it with an impression that, notwithstanding all that is 

 urged, the agencies to which is attributed a cumulative tendency in 

 ice and snow contain within themselves forces that exactly, but in 

 a less obvious form, compensate for the effects which are attributed 

 to them. 



From a mean of temperatures taken north and south of the 

 equator,^ it appears that the temperature of the surface of the whole 

 earth is greater when it is in aphelion than when it is in perihelion. 

 This was attributed by Sir Charles Lyell to the heating effect of the 

 great body of land lying in the northern hemisphere — that body of 

 land being exposed to the summer sun while the earth was in 

 aphelion. Mr. Croll, however, regards it as a necessary result of 

 his theory, attributing it to the loss of heat during perihelion, caused 

 by the southern and more glaciated hemisphere being then turned 

 towards the sun, and part of its heat lost by the agencies just 

 discussed. 



Another and the most important of the causes operating to give 

 influence to the excentricity is, according to Mr. Croll, the great 

 oceanic circulation, in carrying heat from equatorial to temperate 

 and polar regions ; and he has entered into an elaborate examination 

 of the subject to prove that the heat thus transferred is far greater 

 than is generally supposed. He also contends that the position of 

 the aphelion greatly influences the direction of these currents. His 

 argument is too long to summarize; but in the case of the Gulf- 

 stream, for instance, his contention is that with the main configura- 

 tion of the great continents unaltered, this stream, instead of flowing 

 as it now does, would during the glaciation of the northern hemi- 

 sphere, begin so much further south in mid- Atlantic that, instead 

 of entering the Gulf of Mexico and being thence deflected north-east- 

 Avards to Northern Europe, it would be deflected by the coast of South 

 America southwards, as in fact one part of it now is deflected. This 

 alteration Mr. Croll deduces from a previous hypothesis which he seeks 



^ I am not aware on what observations these temperatures are based ; but if they 

 were taken at land stations exclusively, or preponderatingly, the fact alleged to 

 result from them may not be free from question. 



