592 EIGHTH PACIFIC SCIENCE CONGRESS 



also obtained hourly during the time study with the G.E.K. Three 

 hydrographic stations were occupied at corners of a 30-mile square about 

 the seamount to obtain dynamic heights for comparison. The time 

 study with the G.E.K. was performed in depths ranging from 1,500 to 

 600 fathoms and between 30 and 15 miles northwest of the seamount. 

 The ship drifted south during the period. 



The direct current measurements also show rotary changes contain- 

 ing tidal and inertial components. The basic periods are less well 

 defined because of the motions of the ship, but these motions are small 

 compared to those of a ship anchored in deep water. It is assumed in 

 these two experiments that there should be some similarity in the cur- 

 rents on a sharp isolated seamount to those in the adjacent deep water. 

 On the other hand, considerable distortion near the seamount would 

 not be surprising. 



The results of harmonic analysis are given in Table I, for both 

 the direct measurements and the G.E.K. Only the 16- and 12-hour com- 

 ponents are considered of primary importance, but the higher har- 

 monics are presented to suggest the magnitude of the amplitudes which 

 could result from random data in a series of this length. The contribu- 

 tion of each constituent is assumed to be expressed in the form 



t/„ = V^ cos (9 - Ki) 



r/e = ^e cos {6 — Ks) 



where v^ and v^ are the instantaneous values of the north and east com- 

 ponents of velocity, V^ and V^ are the corresponding amplitudes, 9 is 

 the time angle of the constituent and kx and ko are the local epochs, 

 the negative of the conventional phase angle, the origin of time being 

 the time of local lunar transit on the first day of the anchor station. 



If K2-K1 expressed as an angle less than 180° is positive, rotation 

 of the current vector with time is clockwise. In particular, if K2-K1 

 = 90° and V^ = V^, the current hodogram for the constituent is a 

 circle. Theoretically, circular changes are to be expected in the inertial 

 component and generally elliptical changes in the tidal component. 



It is evident that most of the motion is accounted for by inertial 

 and semidiurnal constituents, the former preponderating. The diurnal 

 constituent is probably of significant magnitude, but the others are 

 questionable. The phase difference between north and east components 

 in these three constituents corresponds to clockwise rotations, as would 

 be expected from the deflecting force of the earth's rotation. In the 

 inertial constituent, it is very nearly 90° for both the direct measure- 

 ments and the G.E.K. In the G.E.K. results, the two amplitudes are es- 

 sentially the same, which satisfies the condition for circular rotation. 

 Further deductions from the phase relations will be attempted at a 



