The short titles ate used in the remainder 

 of the text. 



A,C. and Alternate Polarity are similar 

 (fig. 3) in that electrodss are constantly 

 reversing in polarity. A,C, and Alternate 

 Polarity differ in cyclic rate and wave 

 shape. D.C. and Pulsed D.C. are similar 

 because the electrodes remained at the same 

 polarity (fig. i). If polarity is not of 

 importance, these conditions may be expected 

 to be as effective as sequentially energized 

 arrays in which the field polarity remains 

 constant. 



In these exploratory experiments, the 

 electrodes in the array were sequentially 

 energized (Positive Upstream sind Positive 

 Downstream) with pulsed direct current. The 

 current was applied to adjacent electrodes 

 in pairs in sequence from one end of the 

 array to the other, and after the last pair 

 of electrodes had been energized the sequence 

 started again with the first pair (fig. 4). 

 The positive electrode was always in the 

 sjime position relative to the negative elec- 

 trode regardless of the direction in which 



the field moved (upstresun or downstream). 

 The direction of the movement of the field 

 was controlled through a switching unit. 



When sequential switching is used, the 

 fish moving downstream with the water cur- 

 rent always encounter an array in which the 

 directional field is oriented at an aingle 

 to the direction of water flow, aind if 

 polarity of field is important, they will 

 be more effectively guided thain by other 

 types of arrays. In arrays using A.C. , 

 D.C, Pulsed D.C, and Alternate Polarity, 

 the direction of field is different in dif- 

 ferent areas; in effect, it is half one 

 direction and half the other. In a sequen- 

 tially energized array, the direction of the 

 field polarity is constant. 



The results of the two sets of prelimi- 

 nary trials are listed in table 1. These 

 trials gave an estimate of the comparative 

 effectiveness of the several types of ener- 

 gizing. Under the conditions used here, 



Direction of 

 Electric Current 



r®' 



Q 



Q- 



PATTERN 1 







.©^ 



Direction of 

 Water Flow 



Direction of 

 Woter Flow 



o 



o 







o 



KxT Direction of 

 Electric Current 



FIRST PULSE 



Direction of 

 Electric Current 



0- 



©' 



.0^ 



,0 



0- 



PATTERlNl II 



Direction of 

 Woter Flow 



Direction of 

 Woter Flow 



o 



o 



o 



-0 



f~^^^'^ Direction of 

 ® Electric Current 



SECOND PULSE 



Figure 3. --Field polarity relations of a totally energized 

 array. A.C. and Alternate Polarity changed from pat- 

 tern 1 to pattern II continuously. D.C. and Pulsed 

 DC. produced either pattern 1 or pattern II, but not 

 both. Circles represent electrodes in the array. 



Figure 4. -Sequential energizing with the positive polarity 

 always upstream. Only one pair of electrodes was ener- 

 gized with each pulse, and after the fourth pulse the 

 first pair was energized again--direct current was pulsed 

 in square waves; only two pulses are shown. Circles 

 represent electrodes. When the sequential energizing 

 was applied with the positive polarity downstream, the 

 pulses started at the upper end of the array and were 

 switched from pair to the lower end. 



