30 MADEIRA METEOROLOGIC. PART in. 



Of the source of Madeiras abundant Watery Vapour. 



Whence, then, does Madeira derive her anomalous 

 and mostly unseen, yet now fully proved, excess of this 

 solar radiation, damping, watery vapour, above every 

 island or coast-line round about it ? 



From that most powerful of all sources for giving 

 forth abundance of moisture viz. a warm ocean current. 

 So far indeed as the classical Gulf Stream is concerned, 

 the chief and warmest part of that keeps, while in low 

 latitudes, more to the westward side of the Atlantic, and 

 should visit neither the Azores nor Madeira. But a 

 recurving branch of it, after entering the Bay of Biscay, 

 turns down southward by the coast of Portugal, and then 

 has more opportunity to dominate Madeira than the 

 Azores. Wherefore, to quote once more The Voyage of 

 the Challenger, Vol. II, p. 56 and the maps, we find the 

 sea-temperature at Madeira sensibly higher, viz. 72*0, 

 than at the Azores, where it is entered as 70*6 ; but at 

 both places greatly above the mean temperature of the 

 air for the latitude parallels they are in. 



Again we find, by the same admirable authority, that 

 the sea-temperature in the Canarian Archipelago, though 

 that be nearly five degrees of latitude more to the south, 

 is yet very sensibly colder, or 69*25 only. Such an in- 

 verted result, of course, implies that the recurving ocean- 

 current which, Coming last from the north, warms up 

 Madeira, does not reach the Canarian Islands. What 



