2l6 



DISCOVERY REPORTS 



may be cited. It is suggested on p. 140 that this may have been the result of a recent 

 change of wind. 



Table XX. Fluctuation of surf ace temperature on 3. vi. 31, on a course 

 of 2S3° fi'om Coquimbo Harbour to 28° 47' S, 71° 44' W 



Temperatures are found to vary from one year to another in a way apparently 

 unrelated to seasonal changes. The anomaly between our records and those of Schott 

 at Arica have been noted on p. 203. In Pisco Harbour the water inshore is sometimes 

 warmer than offshore, sometimes cooler. In September 1927 and November 1929 the 

 'Emden' and 'Nitocris' registered respectively less than 15 and 16° C, and the water 

 offshore was presumably warmer. But Murphy in 1919 and we ourselves in 1931 found 

 the reverse. He found 20-00° and 20-56° C. in October and November, and we found 

 19-10° C. in June, whereas southwards of Paracas Peninsula readings were as low as 

 14-89° C. We have unfortunately no salinity observations with which to confirm 

 Murphy's suggestion that high temperatures here may be explained by the discharge of 

 freshet waters from the Pisco River. If the swirls altered their position as suggested on 

 p. 210 these changes would be readily explained. 



Changes in the distribution of surface isotherms from day to day, almost from hour 

 to hour, will have been noted in the paragraphs dealing with the effect of wind upon 

 upwelling. To these examples may be added a record of the temperatures in the con- 

 vergence region off Capo Blanco before and after the ship's sojourn of five days in 

 Talara. The changes in the probable distribution of isotherms are illustrated in Figs. 70 

 and 71. Such changes as these have been noted by many earlier observers and may be 

 regarded as a normal feature of this coast. 



Lavalle (1924) has described an invasion of the coastal waters of Peru by a counter- 

 current which occurs annually between the months of April and July, and which he 

 supposes to originate from the Equatorial Counter-current. Its strength varies with the 

 year, but its convergence with the cool coastal water produces aguaje, and in 1923 drove 

 away the guano birds. 



Lavalle publishes records of surface temperature off the Guaiiape Islands and Palo- 

 minos Island for the months of April, May and June during the years 192 1-3. From 



