FOREWORD 
The following paper has been compiled from a series of lecture 
notes made by the writer when he took an advanced course on ocean- 
ography under Prof. Bjorn Helland-Hansen, Geo-Physical Institute, 
Bergen, Norway. Writers of textbooks on oceanography, fail from 
time to time, due to the rapid growth of this science, to keep pace 
in print with the newest methods in practice. The need for the 
appearance of the present treatise is emphasized when it is realized 
that a complete exposition of the methods elucidated herein has never 
before, to the writer’s knowledge, been collected in a single publica- 
tion, and the particular hydrographical information, prior to this, has 
been unavailable short of personal instruction in Europe. Although 
the illustrations to be found throughout the paper are in most cases 
examples taken from observations of the International Ice Patrol off 
Newfoundland, and although the bulletin is intended especially to 
assist the prosecution of Ice Patrol service, the application of the text 
is, nevertheless, quite broad in its scope. It is therefore recom- 
mended to the attention of all students interested in the subject of 
physical oceanography. 
The foundation upon which this paper rests was first laid down by 
Prof. V. Bjerknes, (see “‘ Dynamic Meteorology and Hydrography,” 
Carnegie Institution publications, Washington, 1910-11). In the lines 
of history which record attempts to apply mathematics to the natural 
sciences this treatise by Bjerknes stands out as one of the most 
successful and progressive. A perusal of the book can not fail to 
impress one with the infinite care and exactitude with which the 
theories have been presented and the exposition developed. It 
is a model of scientific treatment, but he who is searching for a 
practical method directly applicable to a hydrographical problem 
is bound to note the absence of just this sort of pertinent information. 
Since the time when Bjerknes’ theories became recognized by scien- 
tists there have been a few oceanographers, especially Helland-Hansen, 
Nansen, Ekman, and Sandstrom, who have done much to give the for- 
mul of motion a practical application to the sea. Asa result of such 
development we are now supplied with a scientific method whereby 
if the temperature and salinity of the ocean are given from several 
known depths and stations the direction and velocity of the currents 
even in the deep water off soundings can be computed and mapped. 
In this connection it may be of interest to know that the currents 
calculated from the observational data collected in 1922 off the 
Grand Banks have been found to agree very closely with the drifts 
of the icebergs of that same year and region. 
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