Before he set out on his Pacific 

 voyages Cook spent several years 

 making excellent surveys of eastern 

 Canadian and Newfoundland coasts. 

 His chart of the St. Lawrence was 

 made before the fleet took General 

 Wolfe's men up the river to Quebec. 





himiin,.i^n.j.ju „ 



James Clark Ross 



This pocket sun compass was used by 

 Sir James Clark Ross during his _ 



Arctic and Antarctic expeditions. 



This map of the North Polar regions 

 by Sir John Barrow shows the state 

 of knowledge when Admiralty rewards 

 were offered for achievements in 

 Arctic exploration. 



Enormous tabular bergs like these are 

 formed by the breaking of the shelf ice 

 around the Antarctic continent. Such 

 icebergs would have been seen by Sir 

 James Clark Ross during his voyage to 

 the Antarctic. 



Fridtjof Nansen 



This illustration from Farthest 

 North shows Nansen taking temperature 

 measurements of deep water on 

 July 12, 1894. Samples were taken 

 at different depths from the surface 

 to the sea bottom. Among other 

 unexpected discoveries, Nansen found 

 that the Arctic Ocean was much 

 deeper than previously thought, and 

 that warmer, saltier layers of water 

 were under the cold surface waters. 



The "Nautilus" 



A certain amount of open water in the 

 form of leads appears in recent photo- 

 graphs of the area near the North Pole 

 under which the Nautilus passed. 

 This condition is rather different 

 from the very heavy pack in which the 

 Fram drifted somewhat to the south. 



This illustration of the control room 

 of the Nautilus gives some idea of 

 the complexity of the instruments 

 used in navigation under the ice. 

 From the time of Cook until 1900 

 instruments of navigation changed 

 little; but with the impetus of two 

 great wars the art of navigation has 

 been greatly aided by radar, the gyro- 

 compass, echo sounder, and inertial 

 navigation systems. 



251 



