THE HYDRODYNAMICS OF CANADIAN ATLANTIC 



WATERS. 



By J. W. Saxdstrom. 

 PREFACE. 



Dr. Johan Iljort has entrusted me with the task of working up, in dynamic form 

 the results, of his hydrographical observations in the Canadian Athmtic waters. It 

 has been a great pleasure to me to undertake this work, as the observations, being 

 restricted to the upper strata of d5^lamic interest, and with the consequent limitation 

 in point of time, may be regarded as almost simultaneous; a feature of great import- 

 ance when dealing dynamically with the material. In addition to this, the area in 

 question is a most interesting one, presenting as it does a well-defined mass of 

 water acted upon by various and very considerable forces. In the course of the work, 

 valuable assistance has been afforded me by Mr. Paul Bjerkan's clear and concise 

 report of the expedition, Mr. Thorolf Rasmussen's excellent draughtmanship in the 

 elaboration of my rough pencil sketches, and Mr. W. J. A. Worster's translation 

 into English of my hastily compiled Swedish text. Without such co-operation, I 

 should scarcely have been able, in the scanty leisure left me by my official duties 

 and other obligations, to carry through the work at all; as it is, I hope that the 

 following pages may prove of some value, not only in discussion of the observations 

 in question, but also as contributing to the general comprehension of various 

 phenomena in the oceans of the world, in regard to which the conditions prevailing 

 in Canadian waters may be taken as affording analogy and illustration. 



The " Survey of Tides and Currents in Canadian Waters," " The Currents in 

 the Gulf of St. Lawrence," and other publications kindly placed at my disposal by 

 Dr. Hjort, contain a mass of most valuable observations as to the movement of the 

 surface water in the gulf of St. Lawrence and adjacent waters.* A good indication 

 of the reliability of these observations is the fact that the popular but erroneous 

 theory of currents due to the action of wind, has here been abandoned. Instead of 

 this, we frequently find the correct observation that a current may arise, or increase 

 in force, some time before the appearance of a storm, such currents being as a rule 

 in a direction contrary to that of the coming wind. These phenomena, which are 

 explained by Bjerknes' circulation theory, give the observer generally an impression 

 that the water in the sea has a very remarkable and unexpected tendency to opposi- 

 tion against the forces striving to act upon it. The usual primitive conception as 

 to the laws which govern movement in liquids will not sirffice to explain such para- 

 doxical phenomena; it will be necessary to introduce new ideas, for the proper com- 

 prehension of which a considerable amount of mathematical knowledge will 

 frequently be required. On the other hand, it seemed to me of the highest importance 

 that the interested obseners in the Canadian Atlantic waters, and also in other parts 

 of the globe, should be able to familiarize themselves with these new principles, and 

 I have therefore endeavoured to get around the mathematical difficulties as far as 

 possible by extensive use of graphical illustrations, and by reference to well-known 



* This series of valuable publications, embraces the results of many years' investigations 

 by Dr. W. Bell Dawson. D.Sc, F.RS.C, etc., head of the Dominion Tidal Survey, Ottawa, and 

 the staff under his direction. 



