126 LITERATURE ON TORRENTS. 



accordance with fact, that in accordance with that unity which pervades 

 every thing, it is possible to indicate a way by which it may be utilised ; 

 and this all the more tllat such a way there is, based on the very laws 

 regulating torrential phenomena which have been brought under 

 consideration. 



" It is this consideration which has determined me to devote some pages to 

 that interesting agricultural operation known under the name of colmatage, 

 or warping, and practised by the Egyptians from time immemorial with 

 great skill. 



" To transform deserts into meadows — stony ground, absolutely sterile, 

 or producing only a sorry pasturage, into alluvial lands, capable of bearing 

 acoveringof the most luxuriant and richest vegetation- — is certainly not only 

 one of the most lucrative enterprises, but also one, in every aspect of it, most 

 interesting. Everywhere, where it is has been tried in favourable circum- 

 stances, it has produced results surpassing all expectations which had been 

 entertained. 



" There exist in France extensive districts, especially in the south, in 

 which this operation might be carried out advantageously. 



" The immense plain which extends from the town of Aries, in Provence, 

 to the sea on the left bank of the Ehone, known under the name of the 

 Craw, is in its central part a veritable desert of forty thousand hectares, 

 covered with pebbles, thoroughly burned up by drought in summer, but 

 where, during the rainy season in winter, there grow some stalks of herbage 

 on which the flocks of transhumant sheep feed. 



" The fertilization of this plain by colTnatage, by means of the waters of 

 the Durance, would be of immense benefit not only to Provence but to the 

 whole country. It would be there a creation of enormous agricultural 

 wealth, which would, without fail, have a reaction on the national wealth 

 and the general well being." 



He statesthatthe credit of first entertaining this idea does not belong to him j 

 that it has again and again engaged the attention of men given to the study of 

 natural phenomena, and of great ameliorations of which terrestrial condi- 

 tions are susceptible ; and he gives great credit more especially to M. 

 Scipion Gras for what he had done and was doing to promote the enterprise. 

 Having done so, he proceeds to expound his views of what might be effected. 



Next in importance to preventing the devastations occasioned by inunda- 

 tions, by the washing away of earth and earthy materials from the higher- 

 lying basins drained by torrents, and by the deposit by these on fertile 

 fields and valuable lands of a covering of sand and gravel and stones, the 

 detritus of mountains washed away by the torrent in its rage, he seems to 

 have deemed the plan of so constructing water-courses that, where 

 practical or desirable, these should be made to make some compensation 

 for the mischief done by them, or by others of their kind, by covering 

 barren plains with fertile soil. 



As the result of the study of natural phenomena, he states, that on pure 

 clay a gazonnement of herbage is not produced, but that it developes itself 

 with great vigour on miscellaneous deposits, and this gives rise to the 

 speedy formation of an upper layer of vegetable soil, and that thus, in a 

 very short time, there is produced there fertile grounds requiring only in 

 addition a little manure to promote their fertility. 



Leaving the subject of- torrents, except in so far as their phenomena might 



