230 DISCUSSION OF THE DESICCATION QUESTION. 



reference has already been made.* Parts of this investigation are, from the 

 nature of the case, extremely vague ; while in regard to certain regions the 

 evidence seems to be quite full and convincing. 



So far as the present writer is able to make out from a careful perusal of 

 Arago's work, it appears that the evidence collected by him does on the 

 whole point to a deterioration of the climate of the world, in the sense of 

 a refrigeration ; and that for certain countries the facts furnished in the 

 volume in question, supplemented in some cases by more recent information 

 from other quarters, do justify us, most decidedlj', in drawing the inference 

 that their climate has become colder to a quite appreciable amount. 



Here a few words may be introduced as to the geographical position of 

 those regions which might be expected to furnish evidence of the kind here 

 called for. Of course only countries sufficiently civilized to be in possession 

 of historical archives of some completeness, and going back to times consider- 

 ably remote, would be likely to be of help to us in this investigation. For 

 instance, it is very possible that if we had some tolerably complete record of 

 the movements of the various aboriginal tribes or nations on this continent 

 from the earliest period of its inhabitation by man, this information could 

 hardly fail to throw light on the climatic question. But in the absence of 

 any written history, and wnth only vague traditions and scanty monumental 

 relics to guide us, we are likely to be left for an indefinite period in doubt 

 as to how for those indicated migrations from north to south were the result 

 of an irresistible impulse to escape from the rigors of a climate growing too 

 severe for an easy or comfortable existence into one better adapted for that 

 end. In regard to the countries about the Mediterranean, on the other hand, 

 of which we have more or less complete written descriptions going back for 

 two thousand years at least, and in some cases monuments with inscriptions 

 and pictorial illustrations throwing light on times much more distant from 

 us than that, we have already seen that evidence of climatic change of the 

 most convincing kind, drawn from historic records, has been furnished for 

 that region. Indeed, there is reason to believe that when this subject 

 comes to be more systematically investigated, there will be much more 

 light thrown upon it from that quarter. 



Again, if a country had, within the historic period, just reached the point 

 where, owing to the deterioration of its climate, it had become difficult for 



* Siir I'Etat Tliennometri(|ue du Globe Terrestre. CEuvres de F. Arago. Paris, 1865. Notices Scientifiques, 

 Tome V. pp. 184-646. 



