334 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



that causes a riisli of the sea from one hemisphere into the other ; 

 and so cataclysms are produced at regular intervals of 10,500 years. 

 In consequence of the inclination of the axis of the earth to the 

 plane of its orhit, we have our change of seasons ; and in conse- 

 quence of the elhpticity of that orhit, the spring and summer of 

 our hemisphere are at present longer than those of the southern. 

 Durino; the excess of time that the sun tarries on our side of the 

 equator, the southern nights are prolonged, so that the night of 

 the south pole — the antarctic winter — is annually a week longer 

 {§ 366) than the arctic. Thus, during the period of 10,500 years, 

 the antarctic regions ^^ill exj)erience 142 years of night, or T^inter, 

 in the aggregate, more than the arctic. Therefore it is manifest, 

 say the catachjsmatists, that, though the two hemispheres do 

 receive annually the same amount of solar heat, yet the amount 

 dispensed hy radiation is very much greater on one side of the 

 equator than the other. The total effect of the alternate cooling 

 do^Ti on each side of the equator causes an accumulation of ice at 

 the pole — when the nights- are longest — sufficient, say they, to dis- 

 turb the centre of gravity of the earth, causing it to take up its 

 position on the icy side of the equator. As the ice accumu- 

 lates, so is the water drawn over from the opposite hemisphere. 

 Such, briefly stated, is the theory which has found very in- 

 genious and able advocates in the persons of MM. Juhen* and 

 Adhjmar.t 



646. This theory is alluded to here, not for the piupose of dis- 

 Are the-ciimates of cussiou, but for tho purposo of directing attention 

 the earth cbangiDg? ^^ certain paxts of \kns> work in connection with it, 

 as Chapters YII. and XXI., for example, and of remarking upon 

 the stabihty of terrestrial climates. Though the temperate re- 

 gions be cooler in the southern than in the northern hemisphere, 

 it does not appear certain that the climates of the earth are now 

 changing. Observations upon the subject, however, are lackmg. 

 The question is one of widespread and exceeding interest ; and it 

 may be asked if we have not in the strength of the trade-winds a 

 gauge, or in then barometric weight an index, or in the equatorial 

 calm belt a thermometer — each one of the most delicate construc- 

 tion and sensitive character — which would, mthin the compass of 



* Couranls et Revolutions de I'Atmospliere et de la Mer, comprenant une 

 theorie nouvellc siir les Deluges Periodiques. Par Felix Julien, Lieutenant do 

 Vaisseau, etc. Paris, 1860. 



t Revolutions de la Mer. Deluges Periodiques. Vox J. Adliemar. Paris, 1860. 



