378 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



of that agent which produces the Newfoundland fogs. It is 

 Th2 fogs of New- ■ spread out over an area frequently embracing seve- 

 fouud!;ind. Yed thousand square miles in extent, covered with 



cold water, and surrounded on three sides at least with an im- 

 mense body of warm. May it not be that the proximity to each 

 other of these two very unequally heated surfaces out upon the 

 ocean would he attended by atmospherical phenomena not unlike 

 those of the land and sea breezes ? These warm currents of the 

 sea are powerful meteorological agents. I have been enabled to 

 trace in thunder and lightning the influence of the Gulf Stream 

 in the eastern half of the Atlantic as far up as the parallel 

 of 55'^ N., for there, in the dead of winter, a thunder-storm is not 

 unusual. 



733. These isothermal lines of 50^, 60^, 70^, 80°, etc., may 

 Aqueous isothermal lHustrato for US the manner in which the climates 

 ^'°^^- in the ocean are regulated. Like the sun in the 

 ecliptic, they travel up and down the sea in declination, and 

 serve the monsters of the deep for signs and for seasons. 



734. It should be borne in mind that the lines of separation, 

 The meeting of cool as drawn ou Plate IX., between the cool and warm 

 and warm waters, wators, or, moro proporly speaking, between the 

 channels representing the great polar and equatorial flux and re- 

 flux, are not so sharp in nature as this plate would represent 

 them. In the first place, the plate represents the mean or 

 average limits of these constant flow^s — polar and equatorial; 

 whereas, with almost every wind that blows, and at every change 

 of season, the line of meeting between their waters is shifted. In 

 the next place, this line of meeting is drawn with a free hand on 

 the plate, as if to represent an average ; whereas there is reason 

 to believe that this line in nature is variable and unstable as to 

 position, and as to shape rough and jagged, and oftentimes 

 deeply articulated. In the sea, the line of meeting between 

 waters of different temperatures and density is not unlike the 

 sutures of the skull-bone on a grand scale — very rough and 

 jagged ; but on the plate it is a line drawn simply with a free 

 hand, merely for the purpose of illustration. 



735. Now, continuing for a moment our examination of Plate 

 The direction of aqne- IV., we are struck witli the fact that most of the 



ous isotlipnns on op- ,, ,,. ,■, , /. ,-, , 



posit.' sides of tiie sea. thermal lines there drawn run from the western 

 side of the Atlantic towards the eastern, in a north-eastwardiy 

 direction, and that, as they approach the shores of this ocean on 



