AGRICULTURE. 



BOOK I. 



water of the river to pass into the sea. Small rivulets and 

 springs can either be turned along the margin of the land 

 gained, and let out at one end of the embankment, where it 

 joins the land, or led the most convenient way to one or more 

 of the valves or flood-gates which it is necessary to make in all 

 embankments for excluding the water within. The water col- 

 lected on the surface of the land gained, will generally be let 

 off by the flood-gates or valves already mentioned ; but where 

 the embankment is extended into the water, this cannot be the 

 case, as the level of the sea will generally be above the level of 

 the land. In this instance, windmills for driving pumps must 

 be placed at proper distances, according to the particular case. 

 Perhaps, in general, one small windmill driving four pumps, 

 would be sufficient for draining 1000 acres. The expense of 

 such a pump-mill would not be above twenty or thirty pounds. 

 By making a small embankment from two to four feet high 

 some distance within the larger one, all the water collected be- 

 tween that and the original shore would be accumulated; and 

 it might be led in a raised canal in the same level to a flood- 

 gate in the outer embankment. This would leave very little 

 water to be drawn up by the pump ; and, in this way, though 

 20,000 acres were gained, one windmill only would be neces- 

 sary*. Often, and indeed in most cases, in place of a wind- 



* As I proposed in the design, estimate, and report, given in for embanking 4000 

 acres in Wigton Bay. 



