of Edinburgh, Session 1885-86. 
433 
colour of the water off the Morocco coast is particularly remarkable, 
for it becomes of a deep and, at the same time, very transparent 
olive-green colour, unusual in any but icy latitudes. Closer in 
shore it loses its transparency. 
A similar phenomenon is observed on the west coast of South 
America. Close in shore all the way from* Valparaiso to Cape 
Blanco, in lat. 4° 30' S., there is a fringe of cold, green, compara- 
tively fresh water teeming with life. In the course of a voyage 
along that coast in April 1885 I found the temperature of the water 
identical in the harbours of Coquimbo in lat. 30° S., and Payta in 
lat. 5° S., namely, 63°*5 F. This is an exceedingly low tempera- 
ture even for the more southerly of the two stations, and is of 
course very much more remarkable for the more northerly one, 
Payta, which indeed may be said to be almost on the equator. 
Along this coast to the southward of Callao there is no marked 
current or stream setting in either direction. In order to bring 
water of 63° ’5 F. by a surface current to so low a latitude as 
5° S. would require a rapidity of transport which, under the circum- 
stances, is inconceivable. Similarly on the African coast the set of 
the water along the shores of Morocco is not towards the equator, 
but towards the north ; and it was observed by Sir George blares, in 
H.M.S. “ Shearwater,” that this cold, in-shore water actually pene- 
trates past Cape Spartel into the Mediterranean. 
In low latitudes there is only one source of cold water, namely, 
the climate of higher latitudes. The water cooled in these high 
latitudes may make its way towards the equator either as a surface 
current or as a movement of the deeper waters. If it is conveyed 
as a surface current, it is exposed to the heating on the way in 
passing through regions of progressively warmer climates, and in 
order to keep a low temperature into anything like low latitudes 
it would require to form a current of great volume and velocity. 
In all latitudes we find almost ice-cold water at a few hundred 
fathoms from the surface, and in fact the nearer we come to the 
equator the nearer does the cold water come to the surface. In 
the latitude of Payta, and away from the coast, water of 60° F. 
would naturally be found at a depth of 100 fathoms ; at the sur- 
face and in the open ocean it would not be found at a less 
distance than 2000 miles. 
2 G 
VOL. XIII. 
