232 THE PHYSICAL GEOGRAPHY OF THE SEA. 



mense pennon floating gently in the current, such a motion as such 

 a streamer may be imagined to have— very much such a motion — 

 do my researches show the tail of the Gulf Stream to have. Run- 

 ning between banks of cold water {^ 1), it is pressed now from 

 the north, now from the south, according as the great masses of 

 sea matter on either hand may change or fluctuate in temperature. 



493. In September, when the waters in the cold regions of the 

 north have been tempered, and made warm and light by the heat 

 of summer, its limits on the left (Plate VI ) are as denoted by the 

 line of arrows , but after this great sun-swing, the waters on the 

 left side begin to lose their heat, grow cold, become heavy, and 

 press the hot waters of this stream within the channel marked out 

 for them. 



494. Thus it acts like a pendulum, slowly propelled by heat on 

 one side and repelled by cold on the other. In this view, it be- 

 comes the chronograph of the sea, keeping time for its inhabitants, 

 and marking the seasons for the great whales ; and there it has 

 been for all time vibrating to and fro, swinging from north to south 

 and from south to north, a great self-regulating, self-compensating 

 pendulum. 



495. In seeking information concerning the climates of the 

 ocean, it is well not to forget this remarkable contrast between its 

 climatology and that of the land, viz. : on the land, February and 

 August are considered the coldest and the hottest months ; but to 

 the inhabitants of the sea, the annual extremes of cold and heat 

 occur in the months of March and September. On the dry land^ 

 after the winter "is past and gone," the solid parts of the earth 

 continue to receive from the sun more heat in the day than they 

 radiate at night, consequently there is an accumulation of caloric^ 

 which continues to increase until August. The summer is now 

 at its height ; for, with the close of this months the solid parts of 

 the earth's crust and the atmosphere above begin to dispense with 

 their heat faster than the rays of the sun can impart fresh sup- 

 plies, and, consequently, the climates which they regulate grow 

 cooler and cooler until the dead of winter again. 



496. But at sea a different rule seems to prevail. Its waters 

 are the store-houses in which the surplus heat of summer is stored 

 away against the severity of winter, and its waters continue to 

 grow warmer for a month after the weather on shore has begun 



