PREFACE IX 



a few months at the British Meteorological Office. London, Eno;land, 

 returning to the ice regions for the seasons of 192G and 1927. In 

 1928 he was the leader of the Manon expedition to Davis Strait and 

 Baffin Bay. 



Two of the i)rincipal problems u})on which the ice patrol has been 

 working in order to provide greater safety for lives and ships on the 

 trans-Atlantic routes luive been {a) the forecasting of the annual 

 number of icebergs which are liable to drift south of Newfoundland 

 during the year, and {h) the construction of hydrodynamic maps to 

 trace the behavior of currents and ice south of Newfoundland as well 

 as to ])redict to approaching vessels the general movement of the 

 ice. Much progress of an encouraging nature has been made in 

 !(t'l)erg forecasting as a result of the statistical work at Harvard 

 I'niversity just mentioned and at the British Meteorological Office. 

 Since the establishment of this service four successes out of five years 

 have been the record. The value of this work is obvious if North 

 Atlantic steamship navigators can be warned in February or March 

 that a heavy ice year, such as 1912. is soon in store, or they can be 

 assured that little danger will exist, such as characterized the year 

 1!>24. The latter problem of constructing frequent current maps 

 lias resulted in a greatly increased knowledge of the movements of 

 ice and ocean currents around Newfoundland, subjects even 10 years 

 ago considered rather liazily. The present practice of two weekly 

 ()!■ monthly maps of the circulation furnishes the best available 

 information to the ice-patrol ships. 



A comprehensive and connected account of Arctic ice has only now 

 been made possible as a result of the Marion expedition to Davis 

 Strait the summer of 1928. Part 1 of the present bulletin is an 

 exposition of the bathymetry of Davis Strait. Part 2 treats the 

 physical oceanography of Davis Strait with especial reference to the 

 circulation of those waters. The present section deals with the drift 

 of the ice in the established currents out of Davis Strait into the 

 North Atlantic. 



During the course of the researches of the international ice patrol 

 many problems of a scientific nature regarding ice and ocean cur- 

 rents have arisen from time to time, and are presented in this thesis 

 as original contributions; among them are the following: What is 

 the prevailing circulation in the north polar basin? Do pack ice and 

 icebergs from east Greenland ever contribute to the supply to North 

 American shores ? What is the cause of " north water '' in Baffin 

 Bay? In what proportion does the pack ice from the Polar Basin, 

 Baffin Bay. and Hudson Bay mix to supply the North Atlantic? 

 AVhat effect does Hudson Strait exert on the Labrador current and 

 its freight of ice? What is the cause of the annual variation in pack 

 ice limits in the North Atlantic? In what proportions do polar 

 glacial lands contribute to the North Atlantic iceberg quota ? Of all 

 the tidewater glaciers in the Northern Hemisphere, which ones are 

 iceberg producing? What is the density of icebergs and their pro- 

 portions of mass flotation? In what proportions do the wind and 

 current enter to control the drift of the berg? What is the normal 

 quantity of pack ice Avhich melts annually, and what is the normal 

 number of icebergs drifting south of Newfoundland ? Is the Labrador 

 current subject to a seasonal variation, and if so, what are the causa- 



