Again, I just mentioned that in the Saffelare district and Jersey they succeed in keeping one head of horned cattle to each acre of green crops, meadows and pasture land, while elsewhere two or three acres are required for the same purpose. But better results still can be obtained by means of irrigation, either with sewage or even with pure water. In England, farmers are contented with one and a half and two tons of hay per acre, and in the part of Flanders just mentioned, two and a half tons of hay to the acre are considered a fair crop. But on the irrigated fields of the Vosges, the Vaucluse, etc., in France, six tons of dry hay become the rule, even upon ungrateful soil; and this means considerably more than the annual food of one milch cow (which can be taken at a little less than five tons) grown on each acre. All taken, the results of irrigation have proved so satisfactory in France that during the years 1862-1882 no less than 1,355,000 acres of meadows have been irrigated,[80] which means that the annual meat-food of at least 1,500,000 full-grown persons, or more, has been added to the yearly income of the country; home-grown, not imported. In fact, in the valley of the Seine, the value of the land was doubled by irrigation; in the Saône valley it was increased five times, and ten times in certain _landes_ of Brittany.[81] The example of the Campine district, in Belgium, is classical. It was a most unproductive territory--mere sand from the sea, blown into irregular mounds which were only kept together by the roots of the heath; the acre of it used to be sold, not rented, at from 5s. to 7s. (15 to 20 francs per hectare). But now it is capable, thanks to the work of the Flemish peasants and to irrigation, to produce the food of one milch cow per acre--the dung of the cattle being utilised for further improvements.