ESSENTIALS OF SUCCESS 211 



The two outfits, therefore, weighed 89 pounds, and a 

 third extra lead brought this total up to 103 pounds. 



Both the sounding leads and the wire were made 

 especially for the expedition, and so far as I know they 

 were the lightest, for their capacity, that have ever 

 been used. 



One sounding apparatus was carried by the main 

 division and the other by the pioneer party, in the 

 early stages of our progress. When there was a lead 

 we sounded from the edge of it; when there was no 

 open water we made a hole in the ice if we could find 

 any that was thin enough for the purpose. 



Two men could readily make these deep-sea sound- 

 ings by reason of the lightness of the equipment. 



The distance which we traveled day by day was at 

 first determined by dead reckoning, to be verified later 

 by observations for latitude. Dead reckoning was 

 simply the compass course for direction, and for distance 

 the mean estimate of Bartlett, Marvin, and myself as to 

 the length of the day's march. On board ship dead 

 reckoning is the compass course for direction and the 

 reading of the log for distance. On the inland ice of 

 Greenland my dead reckoning was the compass course, 

 and the reading of my odometer, a wheel with a cyclome- 

 ter registering apparatus. This could not possibly 

 be used on the ice of the polar sea, as it would be 

 smashed to pieces in the rough going. One might say 

 in general that dead reckoning on the polar ice is the 

 personal estimate of approximate distance, always 

 checked and corrected from time to time by astro- 

 nomical observations. 



Three members of the expedition had had sufficient 



