A NEW JAPANESE G.E.K. 847 



the south side of the main island of Japan and passes through the row 

 of Iz islands to Nojima-zaki. We attemped the first experiment of the 

 measurement on Kuroshio, off the Point Nojima-zaki. 



Three square courses and two zig-zag courses were made as shown 

 in Figure I. At every point of turning, the measurement was tried. 

 The velocities measured by our method are shown in the following 

 table. The points of survey stand in ioiu" rows, so the values may be 

 classified into four series. The series 4 farthest right is considered 

 to be near the edge of the current. 



On the other hand, we found the amount of drift of the ship from 

 the difference between the positions, surveyed by the triangular method 

 to land, and those calculated from ship velocity, time duration and 

 direction. 



At every drift is 1.1 kt, 1.3 kt and 1.4 kt, and the vectorial mean 

 is 1.26 kt. Comparing these values of drift of the boat with the former 

 values 1.37 kt, difference was found to be only 0.1 kt and the direction 

 coincided with the accuracy of the compass, 5°. 



In conclusion, the accuracy of triangular survey by the sextan meth- 

 od is rough as known generally, but the two values coincided well. 

 Furthermore, the mean values of the three series of the G.E.K. method 

 coincide with each other very well. The individual values differ from 

 the mean values of the 1.37 kt, ^vith the ran^e of error as ±0.25 kt 

 This accuracy has not been confirmed till now with more accurate meth- 

 ods, yet the statistical values will explain well about the accuracy. 

 2. Along Iz Island. 



In the south of the Iz Peninsula, Shizoka Prefecture, there lies a 

 roAv of islands from north to south. We call them Iz 7 Islands. The 

 warm current Kmoshio flows through this row of islands from west to 

 east. For the second experiments, we surveyed Kuroshio around this 

 row of islands between two peninsulas, Bohsoh Peninsula and Iz Penin- 

 sula as shown in Figure 2. Figure 3 shows the recording chart. The nu- 

 merical figures show the time; those bet^veen arrows in middle circle 



