INVESTIGATION OF TEMPERATURE CHANGES. 235 



and, although this is not exactly the place in which such a discussion should 

 be opened in the present volume, it will be permitted to state briefly the 

 views of the illustrious physicist on the point in question. That there could 

 have been a general change of climate all over the world he thinks impos- 

 sible, because it has been proved that there had been no change in Pales- 

 tine. Of the present writer's opinion of the value of that proof the reader 

 has already been informed, and the reasons given for it. The cause must 

 therefore, as Arago thinks, be a local one. The influence of a change of jaosi- 

 tion in the Arctic ice-fields is then discussed, and the sufficiencj' of that as a 

 cause of the cooler summers not admitted. He then falls back on cultivation 

 of the soil and disforestinsr of the countrv as the real aa-ents of the mischief. 

 The reader will notice that while removal of the forests is usually considered 

 to be the cause of heat and dryness, it is here made responsible for just the 

 opposite effects. The arguments by which Arago supports his view that the 

 change of climate in France and England is due to man's interference with 

 nature, are indeed most noteworthy. It is that all this kind of effect is 

 known to have resulted, on an immense scale, in the United States from 

 clearing away the forests and cultivating the soil* [defrichement]. He thus 

 describes the marvellous changes wrought in our climate by the hand of 

 man. After stating the flicts in regard to the cooler summers in France, as 

 already mentioned, he goes on as follows: "These same modifications, there 

 is a country where they are now going on. They are developing themselves 

 there under the eyes of an enlightened population ; they proceed with aston- 

 ishing rapidity ; they must, in some sort bring on at a blow [coup sur coup] 

 those meteorological changes which several centuries have hardly sufficed to 

 render perceptible in our old Europe. This country — every one knows 

 which one I mean — is North America. Let us see how these clearings are 

 changing the climate. The results can evidently be applied to the ancient 

 condition of our own countries, and we .shall thus be able to dispense with 

 a priori considerations, which in such a complicated matter would probably 

 lead us astray. Over the whole extent of North America tjiere is a general 

 agreement in recognizing that clearing up the country has changed its cli- 

 mate ; and that this change is becoming more and more evident ; that the 

 winters are now less severe and the summers less hot ; in other words, that 



* The word " defrichement " includes both ideas, thnt of cutting down the forests and of cultivating the land 

 afterwards. " 11 se dit en parlant d'une terre inculte dont on arraclie les mavivaises lierhes, les arbres, les brous- 

 sailles, les epines, pour la cultiver ensuite." Diet. Fr. Acad. It answers most nearly to our word " clearing." 



