40 FISH CULTURE. 



water could be regulated ; but the water was not 

 drawn from the bottom ; a flexible pipe (d) was fixed 

 to the stop-cock inside the cistern, and this was floated 

 nearly to the top of the water, so that all deposit, &c. 

 sunk to the bottom out of the way, and did not pass 

 through the pipe. In the cistern there was, of course, 

 a waste pipe (a). 



Immediately under the stop-cock, the first trough 

 was placed. These troughs were made of half-inch 

 slate. They were three feet long, seven inches wide in 

 the clear, and five inches deep, and were capable of 

 holding 3,000 ova each. Near the further end of the 

 trough was a small pipe, projecting from the side, 

 through which the water ran into the next trough. 

 The second trough was placed side by side with the 

 first, but about two inches lower. The water fell 

 from the pipe at the far end, travelled through the 

 second trough, and thence, through another pipe at 

 the near end of the second trough, into a third trough 

 similarly placed with discharge pipe at the far end, 

 the fourth having it at the near end again, and so on ; 

 and thus there were arranged side by side, but in the 

 form of a flight of stairs, twelve of these troughs, 

 capable of holding some 40,000 ova ; 1 a waste pipe (c) 



1 It would have been just as easy to have had twenty troughs as 

 twelve if needful. "With the twelve troughs some 40,000 ova were 



