232 



DEPARTMENT OF THE ^t^AYAL SERVICE 



region. Doubtless, also, similar forces of resistance oppose the inflow of the Labrador 

 current into Belle Isle strait. 



Within the gulf of St. Lawrence, it is noticeable that the isosteric surfaces as a 

 rule lie deeper in the peripheral portions than in the central part. This suggests the 

 action of a force tending radially outward from the centre; evidently the centrifugal 

 force occasioned by the cyclonic circulation of the water in the gulf. 



Many other interesting details may be seen from Plates X and XL In section 

 IV, for instance, the TOO isosteric surface lies deeper in the middle of the sound than 

 off the Gaspe coast, evidently a quite abnormal situation, due to some strong external 

 force, which, at the time when the section was taken, must have been operating in a 

 direction from the Gaspe coast to Anticosti, probably a strong south west wind. 



5. STABILITY OF THE WATER IN THE NEWFOUNDLAND AEEA. 



The stability of sea-water may conveniently be characterized by noting the num- 

 ber of isosteric surfaces per 10 metres of depth. The third column in table 1 shows 

 this value for all depth intervals in the present investigations. 



It is of great importance to find a method of graphic illustration for this feature, 

 indicating the condition of the water. After various attempts, I have selected the 

 following as being most convenient. The state of a vertical in the sea is represented 

 by a vertical line, the thickness of which is drawn proportionate to the stability. Plates 

 XII and XIII illustrate, in this manner, the stability of the sea-water at the hydro- 

 graphical stations with which we are here concerned. 



By this method, homogeneous water is indicated by an infinitely narrow vertical, 

 see fig. 9 a, and water of constant stability, i.e. the specific volume of which decreases 

 in linear proportion to the depth, by a line of equal thickness throughout, (fig. 9 b). 

 In the sea, owing to rainfall and the inflow of fresh water, as also to the heating of 

 the surface water by the sun, the decrease of specific volume with increasing depth is 

 far more marked in the upper water layers than at greater depths. This is correspond- 

 ingly shown in fig. 9 c. During a hea\^ gale the surface water is so stirred as to pro- 

 duce a homogeneous surface layer, the transition here answering to that apparent in 

 passing from fig. 9 c to fig. 9 d. In the spring, the melting of the ice occasions a down- 

 flow of ice-cold water from the surface to an intermediate depth. A homogeneous 

 layer is thus produced, here indicated by the narrowed portions in the diagram, fig. 9e. 



a b 



Fie 



9. — Diagram of the stability of the sea water. 



In the coastal zones, there is often a current of specifically lighter water. Owing 

 to the inflow from rivers and streams, the surface water b., ">mes especially stable. 



