212 THENORTHPOLE 



experience in traveling over arctic ice to enable them 

 to estimate a day's journey very closely. These three 

 were Bartlett, Marvin, and myself. When we checked 

 up our dead reckoning by astronomical observations, 

 the mean of our three estimates was found to be a 

 satisfactory approximation to the results of the 

 observations. 



It goes without saying that mere dead reckoning, 

 entirely unchecked by astronomical observations, would 

 be insufficient for scientific purposes. During the 

 earlier stages of our journey there was no sun by which 

 to take observations. Later, when we had sunlight, 

 we took what observations were necessary to check our 

 dead reckonings — but no more, since I did not wish to 

 waste the energies or strain the eyes of Marvin, Bart- 

 lett, or myself. 



As a matter of fact observations were taken every 

 five marches, as soon as it was possible to take them 

 at all. 



