246 



Arctic Explorations, 



by Spitzbergen (well shown by Dove's charts), and the free pas- 

 aage it would then have across to Behrings Straits, would obvi- 

 ously make so ready an interchange of temperature that we 

 might well hesitate before pronouncing that the polar ocean 

 would be an icy one."^ It would have half the breadth of the 

 Atlantic and make a large body of water to cover with ice. In 

 addition, we have to consider that besides the source of heat 

 from the Atlantic, the ocean, even within the Arctic circle, has 

 at some depth, not very great, a temperature of 40° F. ; for an 

 isothermal plane of 40° bends around the globe within the ocean, 

 from pole to pole, and no temperature colder than this exists be- 

 low it, this being the maximum cold found by sounding in the 

 tropics, and a temperature reached at some greater or less depth 

 in the polar regions. Now as this substratum temperature is 

 due to the pressure and the waters above are correspondingly 

 affected, this cause must have some influence over the power of 

 the cold of the atmosphere to freeze deeply the waters. 



We may therefore safely conclude that so vast a polar ocean, 

 if unencumbered by land, would be to a great extent a clear sea, 



* We repeat in this place a -woodcut copied from one of Dove's charts (in his 

 VerbreituDg der Warme, &c., 1852) reduced one-half in diameter. It gives an idea 

 <>f tlie position of the isothermals ; and we have added the opening (K) at the head 



Baffin 



woos. The temperature in Fahrenheit deforces (the mean Jannarj/ temperatu 



tnxrar^ i**^^*» ^«,.1. „f il__ tr ^1 T /v. t , if !_:_™ V^in 





art of the known lands north of North A 

 connection, the isothennol chart in volume 



IB 



