658 



PRACTICE OF AGRICULTURE. 



Part III. 



land ; or, by stopping the water in its natural course, turn it through mains, cut to 

 convey it another way, to some distant lands, to water them. 



4075. A sluice [Jig. 528 a, b) is made exactly as a ware, only it has but one thorough ; 

 for if there are more than one, it becomes a ware. 



528 



4076. A trunk is a covered sluice, being constructed in all cases where two streams 

 of water are to cross each other at the point of discharge, to serve as a bridge. 



4077. A carriage is a sort of small wooden or brick aqueduct, built open, for the 

 purpose of carrying one stream over another, and is the most expensive conveyance 

 belonging to the business of watering. 



4078. A drain sluice, or drain trunk, signifies such as are placed in the lowest part of 

 a main, as near to the head as a drain can be formed, and situated low enough to drain 

 the main, &c. It is placed with the mouth at the bottom of the main, being let down 

 into the bank ; and from its other end a drain is cut to communicate with some trench- 

 drain that is nearest. It is a contrivance used to carry off the leakage through the 

 hatches when they are shut down, to convey the water to other grounds, or to repair the 

 main, &c. 



4079. Hatches, (Jig- 528 c) are floodgates, variously constructed. A particular 

 kind, which have about a foot, to take off", so as to permit the water to flow over that 

 much of the hatch where it appears to be useful in irrigation has been in use, but is not 

 found to answer. They are best when made whole ; they may be made of any timber, 

 but oak and elm are the best. 



4080. The term head main is used to signify a ditch drawn from the river, rivulet, &e. 

 to convey the water out of its usual current to water the lands laid out for that purpose, 

 through the means of lesser mains and trenches. The head main is drawn of various 

 breadths and depths, according to the quantity of land to be watered ; to the length, or to 

 the fall or descent of the land it is cut through. And it often happens that smaller mains 

 are taken out of the head main ; the only difference between them is, the one being much 

 less than the other, and are mostly cut at, or nearly at, right angles with the other, though 

 sometimes many degrees less. The use of both the large and small mains is to feed the 

 various trenches with water, which branch out into all parts of the meadow, and convey the 

 water to float the land. These smaller mains are by some called carriages, but impro- 

 perly, for it is confounding them with the open trunk, called by that name, as seen above. 



4081. The trench is a narrow shallow ditch, made to take the water out of the mains to 

 float the land with. It ought always to be drawn in a straight line from angle to angle, 

 with as few turnings as possible. It is never made deep, but the width is in proportion 

 to the length it runs, and the breadth of the pane, between that and the trench drain. It 

 is always cut gradually narrower and narrower to the lower end. 



4082. The trench drain is cut parallel to the trench, and as deep as the tail drain 

 water will admit when necessary. It ought always to be cut, if possible, so as to 

 come down to a firm stratum of sand, gravel, or clay. If the latter, a spade's depth into 

 it will be of great advantage ; its use is to carry away the water immediately after it has 

 run over the panes from the trench. It need not be drawn up to the head of the land, 

 by five, six, or more yards, according to the nature of the soil. Its form is the reverse of 

 the trench, being narrower at the head, or upper part, and gradually wider and wider, till 

 it comes to the lower end and empties itself into the tail drain, which is a receptacle for all 

 the water that runs out of the other drains, that are so situated as not to empty themselves 

 into the river ; and therefore it should run nearly at right angles with the trenches, 

 but, in general, the preference is given to draw it in the lowest part of the ground, and to 

 use it to convey the water out of the meadow where there is the greatest descent ; this is 

 generally found in one of the fence ditches : for which reason a fence ditch is mostly used 

 for that purpose, answering two purposes, fencing the meadow, and draining it at the 

 same time. 



4083. A pane of ground is that part of the meadow which lies between the trench and 

 the trench drain, and is the part on whidi the grass grows that is mown for hay ; it is wa- 



