INVESTIGATION OF TEMPERATURE CHANGES. 233 



Afghanistan, once belonging to the last-named country and now to the for- 

 mer. This region has been densely inhabited and highly cultivated, the 

 date-palm flourishing there ; but now it is little better than a desert, a cold 

 wind blowing over the plains during the spring and rendering cultivation of 

 fruit trees impossible. This wind seems, from Dr. Bellew's description, as 

 quoted by Fischer, to be much more injurious to vegetation than it was some 

 hundreds of years ago.* Singularly enough, and, as it appears to the present 

 writer, most unphilosophically, the author of this valuable monograph on the 

 date-palm seems to prefer to ascribe the demonstrated change of climate 

 in the region in question to the neglect of cultivation and general injury 

 inflicted by Tartar invasion, rather than to admit that the increased dryness 

 and coldness is the result of natural causes acting independently of man. 



It will be impossible, for want of space, to go into any detailed examina- 

 tion of the various evidences of change of temperature brought forward by 

 Arago in the volume under consideration ; only some of the instances in 

 which decided results are supposed by that author to have been attained will 

 be mentioned and commented upon. 



After the investigation of the climate of Palestine, to which reference has 

 been made above, Arago takes up various countries, not, however, in geo- 

 graphical order, and devotes more or less space to each one, passing some 

 by with a notice of only a few lines, and dwelling at some length on others. 

 The first one mentioned is China, in reference to which an investigation 

 of Ed. Blot is cited, to the eifect that the climate of that country can have 

 undergone no change since the most remote antiquity [depuis la plus haute 

 antiquitcj.t 



Egypt, the environs of the Black Sea, Greece, and the vicinity of Rome 

 are next passed in review, without any special result being attained, this 

 branch of the subject being very unsatisfactorily worked up, as compared 

 with what might have been done with the existing fulness of available ma- 

 terial. Under the head of "Change of Climate in Tuscany," some interesting 



* Edribi, wlio was born in the year 1099, speaks of tlie existence of the date-palm iu Seistau ; other Arabian 

 geographers mention the same occurrence. 



+ Not having been able to discover where the original paper of Biot was published, the present writer refrains 

 from any comment on what would appear to be an important investigation. A brief resumi of it is given in the 

 I'omptes Rendus (Tome XII, p. 349). From this it seems that the conclusions i-eached by that author as to the 

 permanence in character of the climate of Cliina apply to a zone along the 35th parallel ; and that the results were 

 drawn from a comparison of the ancient records of the times of such occurrences as (he migrations of birds, the 

 transformations of th? silk-worm, and of various meteorological phenomena not specified, with the epochs of the 

 same phenomena at the present day. 



