316 PHYSICAL GEOGRAPHY. 



and from the north coast of Europe, after being reduced to a very low 

 temperature and loaded with vast masses of ice, is poured in a constant 

 stream by the east coast of Greenland, by Baffin's bay, and the straits 

 north of Hudson's bay directly upon the shores of Labrador and New- 

 foundland, and is afterwards carried as a cold inshore drift along our 

 coast. Our north-east and east winds are, in consequence, of low tem- 

 perature, producing an excessive rainfall by their meeting with the 

 warmer south-west currents of our prevailing storms. By another 

 remarkable oceanic current, known as the Gulf stream, enormous vol- 

 umes of water, of almost tropical temperature, are brought into sudden 

 contact with this polar current off the coast of Newfoundland. The 

 warm atmosphere overhanging the Gulf stream is saturated with mois- 

 ture, and on meeting the cold atmosphere of the polar current this is 

 condensed, covering the Grand Banks, the Gulf of St. Lawrence, and 

 the adjacent ocean and land with thick and comparatively constant fogs. 

 These vapors are brought over our state by east and north-east winds, 

 sometimes remaining for days, or, with some intervals, for weeks together, 

 especially in the latter part of summer. The cool fogs of the dog days 

 throughout New England, which are in marked contrast with the sultry 

 heat of that season in the interior, are derived from this source, or in 

 part from a similar condensation of the moisture of southerly winds 

 blowing from the Gulf stream across the cold ocean current along our 

 shores. The obvious effect of these fogs, occurring most notably in the 

 midst of the protracted heat of summer, when streams tend to run 

 lowest, is greatly to diminish the evaporating power of the sun and 

 reserve a large proportion of the rainfall for removal by drainage. 



The conditions of our climate, resulting from geographic and conti- 

 nental position, are thus such as to give increased volume and unusual 

 constancy to our streams. 



PHYSICAL CHARACTER OF NEW HAMPSHIRE AS RELATED TO WATER- 

 POWER. 



The consideration of the hydrographic features of the state is of espe- 

 cial interest, as exhibiting the extent and value of its water-power. Our 

 river systems are hardly more important as a part of the physical geog- 

 raphy than they have already become in their relation to the industries 



