io8 On Similarities in the 



taken from the wash when the ship was going astern had a 

 temperature of 72-8. All the way across the mouth of the 

 Gulf of California the water was very constantly at a tempera- 

 ture of 78 F., with a deep ultramarine colour. Both these 

 characteristics began to change as the mountainous coast of 

 Lower California was approached. At 2 P.M. the temperature 

 fell to 75-8, but recovered again to 77-0 at 4 P.M., when the 

 ship was less than two miles off shore, and to the eastward 

 of Cape St Lucas. The change now became very evident to 

 the senses, and at 4.35 P.M., after the rocky promontory had 

 been passed, the temperature was 73-4, and at 5.45 P.M., 

 while still close inshore, the temperature of the water had 

 fallen to 64-4, and its colour was quite green. On leaving 

 the shore the temperature rose to 66-8, and next morning at 

 8 A.M. it had fallen to 59, when about two miles off Marguarete 

 Island. The number of sharks off Cape St Lucas, and indeed 

 far out into the mouth of the gulf, was quite extraordinary. 

 Quantities of large fish with the glistening scales of salmon 

 were jumping in the water close to the shore round Cape 

 St Lucas. The temperature of the water remained constantly 

 at about 60 F. until, after passing Santa Barbara, the ship 

 rounded Cape Concepcion, when the temperature fell to 52 F. 

 It was 50 at the entrance of San Francisco harbour. 



These sharp transitions are found only close inshore, and 

 they have usually been attributed to surface currents from 

 higher latitudes. This explanation is at variance with the 

 observations of navigators on the coasts, who do not notice 

 any currents which would be strong enough to bring water 

 many hundreds of miles under a burning sun without sensible 

 rise in temperature. The occurrence of these coast areas 

 of abnormally cold water is explained when we recognise that 

 they are the windward shores of the oceans. The trade winds 

 blow from them towards the equator, and in doing so mechani- 

 cally remove water, which has to be supplied from the readiest 

 source. This source is the deep water lying off the continental 

 coast, which is supplied by a gradual drift of cold water from 

 high latitudes. Hence, though the low temperature of the coast 

 waters referred to is due to the cold of high latitudes, it is 



