CRAIGEND PONDS. 243 



tight to this day. The inlet screen differed from those of the 

 ponds above ; it and the outlet screen were formed on the model 

 of the outlet screens at Howietoun, although at that time the 

 importance of all the outlet screens being interchangeable was not 

 realised. A frame of batten was made, and fitted on to the two 

 opposite ends of the octagon ; the frames carrying the zinc slid 

 in grooves in the batten frame. The connection with the 4 -inch 

 pipe was made as before, between the upper and the lower 100- 

 feets ; but as there was no screen-box, the connecting-trough 

 between the lower 100-feet and the octagon was itself provided 

 with a moveable board in the cover, below which the trough was 

 grooved to receive cross-boards to hold clay, thus turning the 

 waste from the lower 100-feet into the three-legged trough c, 

 and so to waste. The screens used in the octagon will be fully 

 discussed when the yearling ponds at Howietoun are described. 

 Below is the detail of the octagon pond. 



The trough from the outlet of the octagon discharged into an 

 open drain. A third 100-feet was commenced, but, as will 

 appear, was abandoned before being finished. A plug-hole was 

 bored in the bottom of the octagon, and a spigot and faucet sani- 

 tary pipe connected by a bend led from the hole to the 6 -inch pipe. 



The plug was turned out of wood ; hardwood is best, as it 

 does not swell so much under water. There is no difficulty in 

 drawing the plug, if a small portion is thickened above the 

 hole, as a light chain, passed through a small ring attached to the 

 end link so as to form a loop, will take a good grip of it ; and by 

 holding a pole on the top of the plug, and passing the loop down 

 over the end of the pole, the plug can generally be involved the 

 first try. 



The 6 -inch drain-pipe (sanitary) terminated in the first well. 

 These wells are now a feature in the work at the Fishery. With- 

 out wells, much time would be lost catching the last fish in a 

 pond ; and most probably many fish would be suffocated in the 

 mud before they could be removed, and a large number would 

 certainly be injured in handling. All this is a vision of the past at 

 Howietoun. The problem has been solved. Time, money, fish, and 



