608 duponchel's peoposals. 



and so important in their possible effects upon immense tracts ol 

 the earth's surface, that they must be considered as projects of 

 geographical revolution, and they therefore merit more than a 

 passing notice. In a memoir already quoted, and in a later work,* 

 this engineer proposes to construct artificial torrents for the pur- 

 pose of grinding up calcareous rock, by rolling and attrition along 

 their beds, and thus reducing it into a fine slime ; and at the same 

 time these torrents are to transport an argillaceous deposit which 

 is to be mingled with the calcareous slime, and distributed over 

 the Landes by watercourses constructed for the purpose. By this 

 means he supposes that a very fertile soil may be formed, and so 

 graded in depositing as to secure for it a good drainage. 



In order that nothing may be wanting to recommend the pro- 

 ject, Duponchel suggests that, as some rivers of Western France 

 are gold-bearing, it is probable that gold enough may be collected 

 by washing the sands to defray in part the expense of such 

 operations. 



In the Landes of Gascony alone, he believes that 3,000,000 

 acres, now barren, might be made productive at a moderate ex- 

 pense, and that similar methods might be advantageously em- 

 ployed in France over an extent of not less than 30,000,000 acres 

 now almost wholly valueless. 



The successful execution of the plan would increase the fertile 

 territory of France by an area of four or five times the extent of 

 Sicily or of Sardinia. 



There seems to be no reason why the same method, applied for 

 such different purposes, should necessarily be destructive in the 

 one case while it is so advantageous in the other. A wiser econ- 

 omy might bring about a harmony of action between the miners 

 and the agriculturists of Cahfomia, and the soil which is removed 

 by the former as an incumbrance, judiciously deposited, might 

 become for the latter a source of wealth more sohd and enduring 

 than the gold now obtained by such a sacrifice of agricultural 

 interests. 



Action of Mem on the WeatTier 



Espy's well-known suggestion of the possibility of causing rain 

 artificially, by kindling great fires, is not likely to be turned to 



* Traite d! Eydraulique et de Qeologis Agricolea, 1868. 



