HOWIETOUN PONDS. 



235 



sunk half an inch clear of the bronze valves ; and to enable me to 

 use the ponds for smaller fish, a frame of oak was constructed, 

 covered with No. 9 zinc, sufficiently large to allow the valve to 

 rise freely inside ; each pond received one of these frames. 

 Below is a diagram of the screen in position, showing valve and 

 straight-eye pipe (Fig. 160). 



Fia. 160 seal 



The valve was provided with a rod passing through the top of 

 the frame, which was covered by two oak boards joining in the 

 line of the aperture through which the rod passed. This rod 

 ended in a loop immediately above the oak cover when the valve 

 was closed. A long rod of iron terminating in a hook was used 

 to lift the valves, and the position of the loop being marked on 

 the side of each pond, no difficulty is encountered in finding them. 

 The next thing done was to put up supports for the covers of the 

 20-feets, so that the lids could be laid back on a fine day without 

 straining the hinges. I find that the less trout-ponds are covered, 

 the better for the fish ; but shallow ponds must be covered at 

 night, or rats, frogs, and birds will rapidly reduce the fry. The 

 earth-slopes on the outer sides of the paths were turfed, and the 

 slopes dressed uniform to a bevel. This tool has been so useful, 



