Pond No, 5 



When weather and other conditions pernxitted, testa were 

 run in Pond Noo 5 two or three times a weekp starting in August 1952 

 and continuing throughout the fallj winterj, and spring. The general 

 arrangement for testing is illustrated in figure 4o 



By means of a 2 -inch pump driven by a 3-ho Po electric 

 motor p water was sucked from outside the "seaward" gates at the 

 western end of the pond, led through a 2-l/2--inch rubber hose along 

 the concrete gate supports to a point near the center of the deep 

 trough in the pond, and then injected into the pond about 5 feet below 

 the surface (from the high tide mark) through an L^shaped piece of 

 2=inch galvanized pipeo Test material was introduced into the flow 

 through a funnel, the base of which was attached to a piece of 3/4- 

 inch galvanized pipe by a rubber hosCo The 3/4'=inch pipe was brazed 

 at an acute angle into a hole in the "down" section of the L-shaped 

 pipes creating a suctions The funnel was located within a small 

 house erected above the seaward gates„ thus effectively screening 

 the operator when waiting to introduce test liquidso 



The pumpe which was rather noisy and which created a 

 strong visible flow of water for about 20 feet into the pond, was kept 

 running for sonne time before as well as during both control and test 

 periods to accustom the fish to both the noise and the currento After 

 tracing the path of the current with fluorescein dyej, an "attraction" 

 area was marked off with two pieces of cord stretched across the 

 pondo one 39 feet and the other 78 feet from the seaward gateso The 

 dye indicated that liquids introduced into the flow would reach the 

 near edge of this area within about 1 minute;, would spread throughout 

 most of the area within about 3 or 4 minutes^ and would for the most 

 part rennain In the area for ain additional 10 minutes before appreci- 

 ably dispersing downstream across the far cordo 



To observe the fish, a wooden tower 20 feet high was 

 built opposite the center of the attraction area on the north side of 

 the pond, A platform and seat on top of the tower was reached by a 

 ladder. As the material was introduced when the fish were starting 

 to return from the far end of the pondj after pouring the nnaterial 

 down the funnel the observer was able to move quickly from the small 

 house to the tower^ climb the ladder, and sit on the platform before 

 the fish approached the attraction area. It is reasonably certain 

 that he was not noticed by the fish either when moving to the platform 

 or when seated on it. Timing ajid counting were conducted from the 

 platfornric Observation was improved by wearing polaroid sun 

 glasses, 



11 



