X PREFACE 



tive factors? What proportions quantitatively of the North Atlantic 

 are cooled by northern ice and by cold water, and which of these 

 agents is the more effective ? Is the effect of ice melting in northern 

 waters sufficient to account for the main system of oceanic circulation ? 

 Does the Labrador current extend down the east coast of the United 

 States? 



This affords me an opportunity to recognize the helpfulness of 

 the following in connection with the compilation and treatment of the 

 subject matter: Dr. Henry B. Bigelow, of Harvard University; Dr. 

 C. E. P. Brooks, of the British Meteorological Office. Those in the 

 Coast Guard to whom I am indebted are Lt. Comdr. N. G. Ricketts, 

 Mr. Olav Mosby, and H. Addingtou. 



