sentences:  Hourly weather observations started September 8, 1937, and reports were transmitted daily to the US Weather Bureau in Washington, D.C. Pilot-balloon observations were made twice daily except during December and January.All observations were continued until the hour of sailing July 7, 1938.MacGregor believed that accurately observing and plotting the development and movement of air masses as they moved across the Arctic would make possible more precise, longer-range Northern Hemispheric weather forecasting.