506 REPOET OF COMMISSIONER OF FISH AND FISHERIES. [40] 



wide, and if steep, narrow. The question whether the slope is to be more 

 or less gentle will depend on the quality of the soil from whicb the ditch 

 is dug, whether it is firm or loose. The grade should also be taken into 

 consideration. The steeper the grade the gentler should be the slopes 

 of the walls of the ditch. In very loose soil the base line of the slope 

 should be twice the depth of the ditch, in medium soil 1.5 of the depth, 

 and in clayey soil equal to the depth. The breadth of the sole may be 

 made to correspond with the quantity of water and the size of the pond; 

 it will be advisible, however, in case the quantity of water in the ditch 

 is as a rule moderate, but rises considerably at times, to make the sole 

 very broad, and dig out from it a small ditch corresi)onding to the aver- 

 age depth of water. In small ponds, where it is not intended to winter 

 fish, the main ditch may be less than 1.5 meters deep, and its other di- 

 mensions should be made to correspond with this depth. If there is a 

 sufficient supply of water, a depth of 1 .5 meters will be ample for win- 

 tering fish, and if the grade of the pond is very steep, and the greatest 

 height of the water above the bottom of the pond is more than one me- 

 ter, it will be well to diminish the dei)th of the ditch by this excess of 

 height over 1 meter. The main ditch, as well as all the other ditches, 

 should be carefully constructed, so that along the entire length the 

 ui^per width and the breadth of the sole remain the same, and the slope 

 is even and smooth throughout, as otherwise there is danger of their 

 being washed out. 



■^. THE SIDE DITCHES. 



In order to drain the pond and lay it dry, small side ditches will be 

 needed, which end at the banks. Their number will dci)end on the size, 

 location, and nature of the i)()nd. Muddy and mossy ponds, containing 

 many reeds, will require more such ditches than ponds with a firm bot- 

 tom, which are free from such obstructions. They should invariably 

 fall towards the main ditch, for they are not only intended, whenever 

 the pond is drained for fishing, to compel the fish, as the water recedes, 

 to fly to them, and thus to cany them to the main ditch and ultimately 

 to the fish-pit, but they should also lead the water by the shortest pos- 

 sible way to the main ditch, and through this to the outflow. When the 

 ponds have been laid dry and planted, they are to serve as receptacles 

 for the rain-water, and as channels through which it can flow off quickly. 

 During the fisheries they are also intended to enable the fishermen to 

 penetrate into the thickets of reeds, and drive into them all fish which 

 may have remained in these thickets, so that they may ultimately be 

 carried to the fish-pit. In large ponds the main ditch and some of the 

 side ditches should be broad enough for a boat to pass through them. 

 The grade of these ditches should be the same, so that the fish do not 

 remain scattered throughout the side ditches, thus making fishing 

 difficult. 



If there are many depressions in the bottom of the i)ond, ditches 

 should be constructed from these to the main ditch, in order to cause 



