HYDROGRAPHIC INVESTIGATIONS 129 



SESSIONAL PAPER No. 38a 



DEDUCTIONS FROM DATA OBTAINED IN THE BAY OF FUNDY. 



A. — Temperature Curves. 



From the corrected data obtained at each station, a temperature curve has been 

 drawn (figs. 1-15), and upon the basis of these curves four profiles have been con- 

 structed representing respectively the three transverse sections and one longitudinal 

 section of the Bay of Fundy. The discrepancies in depth at some stations shown by 

 the curves and profiles are to be explained by the state of the tide when the observa- 

 tions were made. The bottom conformation has been drawn as accurately as possible 

 with the aid of charts. 



If the data for stations I to TV be compared with those recorded in August, 1914,^ 

 it will be observed that, with the exception of the surface temperatures at stations II 

 and IV, all the readings are considerably lower in the new observations, the bottom 

 temperatures averaging 2.7° lower than in 1914. The range of temperatures between 

 the surface and the bottom is thus much greater in 1915, the difference in the surface 

 temperatures being comparatively little. These differences between the temperatures 

 found in the two years are to be explained, no doubt, by the fact that the new observa- 

 tions were taken six weeks earlier in the season than the old ones, when the heating 

 effect of the summer sun and air had had less time to penetrate to the deeper water. 

 Thus there is to be seen a very rapid fall of temperature in the layers of water near 

 the surface (figs. 1-4). In this connection, it must be remembered that the heat con- 

 ductivity of sea water is so slight as to be practically negligible. " The heat conveyed 

 by the sun to the uppermost water-layers cannot therefore be propagated into deep 

 water by conduction, but only through movements of the water-waves, currents, con- 

 vection ' currents,' etc."^ The fact that the deeper water is heated so much in a period 

 of six weeks must be attributed to the vertical mixing of the water by the great tides 

 occurring in this region. 



Another effect of this vertical mixing by the strong tidal currents was referred 

 to in the previous report, namely, the considerable areas of the same, or nearly the 

 same temperature occurring at many of the stations. This is most marked in the case 

 of the stations farther up the Bay, the temperatures at stations X to XV (figs. 10-15) 

 inclusive being practically constant between a depth of 5 fathoms and the bottom. 

 The fact that this uniformity becomes more marked in the upper part of the Bay bears 

 out the theory that the tides are responsible for it, the tides being greatest at the head 

 of the Bay, w'hile the water there is shallower, so that the tides are likely to effect a 

 more complete mixing of the mass of water. 



Helland-Hansen, generalizing upon the basis of temperature curves for four stations 

 distributed over the Atlantic from the Faroe-Shetland channel to the Sargasso Sea says : 

 ''From the surface downwards the temperature falls very rapidly for the first hundred 

 metres; at 100 metres it is 4° to 6° colder than at the surface. Beyond 100 metres the 

 temperature decreases at first much more slowly. . . . The layers in which the 

 temperature changes very rapidly are called 'discontinuity layers' (by the Americans 

 ' thermocline,' and by the Grermans ' Sprungschicht')."^ The curves obtained for the 

 first four Bay of Fundy stations, i.e. those nearest the open Atlantic, (figs. 1-4) agree 

 with these observations to an extent which seems little short of remarkable in shallow 

 and enclosed water, especially where conditions are so peculiar as they are in the Bay of 

 Fundy. Indeed it would hardly seem justifiable to consider the correspondence as more 

 than a matter of chance were it not for the fact that it appears even more clearly in the 

 curves for the same stations in August, 1914. The comparison is made particularly apt 



1 Craigie, E. Home. " A Hydrographic Section of the Bay of Fundy in 1914." Contri- 

 butions to Canadian Biology, 1914-1915. 



2 Helland-Hansen in "The Depths of the Ocean," by Sir John Murray and Dr. Johan Hjort, 

 p. 226. 



3 " The Depths of the Ocean," p. 223. 



