ing experimental signals ranging from intermittent pips to siren 

 effects of several frequencies. The complete unconcern of the fish to 

 any of these signals was convincing that they were unaffected^ It was 

 decided, as a final test of this conclusion^ to beam the transducer 

 across section no. 2 so it would act as a sound "fence" to keep the 

 fish in section noo 1, Tests no. 5l through 58 (Figs. 17 and 13) 

 showed no response,. Tests no, 59 through 6l (Fig, 13) were thought o 

 be indicative^ so these tests were repeated but without success. The 

 remainder of the high-frequency tests, both formal (Figs. l3 and 19) 

 and informal were unproductive. There was no indication that this 

 signal generator or any frequency produced by it would by of any use 

 as a stimulus for leading or guiding small fish. 



An incidental finding of the above tests was an indication of 

 conditioning in the experimental fish. As the trials progressed, there 

 was a distinct tendency for the fish to learn to remain in pen no. 1 

 (Fig. 20) o 



"WAMPUS" - UNDERWATER TURBINE 



In the spring of 19U9 experimentation with sound was continued 

 at the Leetown station with the help of the U. S, Naval Ordnance 

 Laboratory, The first piece of equipment tested was an underwater 

 turbine (Fig. 21) used during World War II as a toxired sound target 

 for torpedoes and mines. This noisemaker required for its operation a 

 500 gallon per minute water pump and a l50 pound capacity air compres- 

 sor (Fig, 22). An overhead trolley line was rigged to enable the sound 

 head to operate at varying distances from the fish in the counting 

 structureo Because of its use in naval warfare^, the sound head^ dubbed 

 the "wampus" early in its development, is still in a classified category. 

 It is not possible, therefore, to describe this underwater turbine in de- 

 tail. Of greater importance, hovjever, is the nature of the frequency 

 band emitted, and its intensity^ which we have obtained permission to dis- 

 cuss in general terms. The msjcimum signal recorded was about 3 volts, 

 which at 56 microvolts per microbar, would correspond to a pressure of 

 about 55<,000 dynes/cm^ This is real underwater thunder. By way of com- 

 parisonj 1 dyne/cm^ in underwater sound is a moderate sort of noise of 

 the sort made by a small boat sloshing along nearby„ A loud underwater 

 sound level would be made by a large slrLp passing at close range, which 

 might register 30-IjO decibels above 1 dyne/cm^. The standard for quiet 

 used by the telephone company is .0002 dynes/cm^. 



Some frequency response curves were obtained on the wampus with 

 and without air and at 100 p s i water pressure, V&th air there was 

 a fundamental frequency of about 50 to ?5 cps, and all harmonics up to 

 3,000 or lij,000 cps. Without air, the fundamental was about 75 to 100 

 cps, and with all harmonics up to 2,000 cps. The shifting of the 



20 



