two o'clock
Dr. Brende showed it to me on his chart -- north , following the 70th West Meridian . Compass corrections as we got further north -- and astronomical readings , these would take us direct to the Pole . I could never fathom this air navigation ; I flew by tower lights , and landmarks -- but to Dr. Brende and Georg , the mathematics of it were simple . At two o'clock we had crossed the route of the Chicago-Great London Mail flyer . But we did not see the vessel . The temperature was growing steadily colder . The pit was inclosed , and I switched on the heaters .