OHAP. xii. WATER-MEADOWS. 881 



carriage in the style of a dam. The turfs are to be made higher than 

 the surface of the water next the banks of the carriage, but a little 

 lower in the middle, in order that the water may pass there. 



The sluice S, by which the meadow is watered, is two feet wide, and 

 three feet nine inches deep. While the meadow is being watered 

 (" flooded " or " drowned "), the hatch or gate of the sluice is drawn 

 up about 2 feet, and then the water passes through an aperture of 5 

 square feet ; by which means, supposing it runs at the rate of 2 feet in 

 a second, the quantity of water thrown upon the meadow is 10 cubic 

 feet in a second, or about 1,000 tons in an hour. A much larger 

 quantity would be more advantageous, though even a less supply would 

 benefit the land. 



Fig. 878. d c d is a section of one of the ridges ; c the carriage on 

 the top of the ridge ; and d d the drains into which the water falls after 

 it has flowed over the land on each side from c to d. 



If there is not sufficient water to irrigate the whole meadow at once, it 

 may be done in two or more divisions. As, suppose the part w c m p 

 on the right, or about half of it, is to be watered first, make a dam 

 across the main carriage at c p, and then the part w op may be watered 

 in the manner described, and the other part will remain dry. In order 

 to water this other part by itself, make a dam across the main carriage 

 at o m, and at the upper ends of the other carriages from o to p ; the 

 water being then let in from the river will fill the other carriages, 

 and flow over this part of the meadow only. 



The dams across some of the carriages may serve very well occa- 

 sionally. Where, however, there is not a sufficiency of water, so that 

 the meadow has to be watered in divisions, it is best to put in small 

 sluices at convenient places in the carriages, in order to be able to turn 

 the water on and off the several divisions of the meadow at pleasure. 



When the water has flowed over the meadow, and is all discharged, 

 any other meadows situated below n may also be flooded in the same 

 manner as the first, and with the same water ; and in some places it is 

 thus thrown over several meadows in succession for some miles. But 

 the fertilising ingredients of the water are diminished after it has been 

 once used for irrigation, and the second or third meadow over which it is 

 made to pass derives less and less benefit from it, the effect being in 

 the latter case chiefly of a physical character. 



Any meadows contiguous to a river may be watered without being 

 laid out in so accurate a manner. If the river is a little higher than 

 any part of such meadows, head mains may be made, and the water 

 conducted to the highest parts, trenches or small mains branching from 

 them between the drains. The nearer the trenches and drains are 

 together, if there is room left to mow between them, the greater will be 

 the advantage. Where there are any hollows, they should be filled up, 

 and the surface made smooth with the earth dug out of the drains, in 

 order that the grass may be mown very close. 



There is another kind l of irrigation termed catch-work, practised in 



1 In 1850, Mr. Philip Pusey, in the ' ' Journal of the Royal Agricultural Society of England, " 



3 L 



