Woeikof — CrolVs Hypotheses of Geological Climates. 167 



(—239° R) was taken as the initial ; but actually the difference 

 is but 80° F. This small difference, as he thinks, is caused by 

 the ocean-currents, which carry an immense quantity of heat 

 from low to high latitudes. That ocean-currents have a great 

 influence on the temperature of our earth I do not deny, but it 

 is not so great as Dr. Croll believes. 



To prove this I will take two places in as different latitudes 

 as possible, and both not influenced by the ocean-currents. 

 The first is Iquitos, on the Amazon, 3^° S. and about 300 feet 

 above sea-level. The mean yearly temperature is 764° F. 

 The reduction to sea-level would make it about 77*8° F., and 

 the reduction to the temperature of the equator would give 78*3. 

 Now Iquitos is more than 1,000 miles from the Atlantic, and, 

 although nearer to the Pacific, yet separated from it by the chain 

 of the Andes. It is to be admitted, then, that the place gives 

 us a good idea of the temperature near the equator, uninflu- 

 enced by the heat-abstracting influences of ocean-currents. The 

 other place which I choose for comparison is Verkhojansk, in 

 1ST. E. Siberia, under 67° 1ST., and having the coldest winter 

 known on our globe, (January, —56° F.) It will, I think, be 

 readily admitted that this place is out of the influence of ocean- 

 currents, bringing heat from low latitudes, and in most favora- 

 ble circumstances for radiation of heat. The mean yearly tem- 

 perature of this place is l - 9° F. ? the reduction to sea-level may 

 bring it to about 2*5. * 



Thus we have, outside of the influence of ocean-currents, the 

 following mean yearly temperature at sea-level : 



Equator 78-3 



67° L. N 2-5 



Difference, 7 5*8 



Reasoning on the premises of Dr. Croll, we ought to expect 

 a difference of 172° F. between the equator and' 67° N. The 

 actual difference is less than half that amount, scarcely over two- 

 fifths ; yet heat is certainly not abstracted from the vicinity of 

 the equator, in the interior of South America, by ocean cur- 

 rents, nor are the continental regions of N. E. Siberia warmed 

 by ocean -currents. 



The Eev. O. Fisherf has already proved that if Dr. Croll's 

 reasoning were right, the mean temperature of the equator 

 should be by 21° F. higher in January than in July, on account 

 of the greater proximity of the earth to the sun in the former 

 month, while it is known that at most places on the equator 



* The actual height is not known, but is in any case small, 

 f 'Nature,' vol. xxi, page 129; reprinted in 'Climate and Cosmology,' ch. iv, 

 omitting some passages relating to the Rev. Fisher. 



