CURRENT AND DRIFT OF THE SHIP 129 



leeward of her outward course which was maintained at 224°. During her run from 

 25 to 100 miles from the coast the force of 

 the wind and drift eased but thereafter in- 

 creased again, rising to force 5 and increasing 

 also the amount of her drift on the end of the 

 line. On her return run on a course of 44° from 

 Sts. WS 653 to 657, the force of the wind 

 lessened gradually from 5 to 4-5, and with it the 

 drift from 12 miles a day to zero. When the 

 wind decreased further to force 4, the ship 

 drifted against it. It appears therefore that 

 during the 58 hours from Sts. WS 647 to 657, 

 while the ship's course was maintained at 224° 

 on the outward and 44° on the inward run, the 

 total drift including leeway amounts to no more 

 than 8 miles a day. In similar wind conditions 

 off Pichidanque Bay where there was no ob- 

 servable current, the recorded amount of 

 drift was more than twice as great. It seems 

 necessary therefore off San Juan to postulate an 

 offshore current flowing south-east against the 

 wind. 



Current was shown to be absent within 

 24 miles of the Callao coast by observa- 

 tions of discoloured water at the Palominos 

 Island control stations and by the well-fixed Fig. 9. Antofagasta. Track of R.R.S. 'William 

 positions of Sts. WS 663-666 (Fig. 10). At Scoresby', June 7-10. St. WS 630 was worked 

 r , ,. r , , , , between the two positions shown. Course set 



farther distances from the shore a leeward „ r c ixfc /; j o c c^ 



270 from St. WS 622 and 090 from bt. 



drift of 20 miles in the space of 28 hours (the wg 629. 

 period between Sts. WS 666 and 671) accords 



with the drift experienced on other occasions. Observations of discoloured water off 

 Palominos Island were first made on June 26, when a patch cinnamon rufous in colour 

 lay south of San Lorenzo Island, its northern margin coming to an abrupt end opposite 

 Palominos Island (Plate XVI, figs. 7 and 8). The boundary line between the cinnamon 

 rufous and the clear water of porcelain blue northwards formed so striking a line of 

 demarcation that it was kept under observation for several days. It was revisited on 

 July I and 15, and in that time, although it had grown less distinct, it had not drifted 

 farther northwards than the northern end of San Lorenzo, a distance of some 4 miles. 

 When observations were repeated in August, current was again insignificant. 



Off the Guafiape Islands northerly drift amounted to 12 miles a day, rather more 

 than would be accounted for by the southerly wind of force 1-2 which prevailed at the 

 time, and some of this must therefore be attributed to current (Fig. 13). 



