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DEPARTMENT OF THE NAYAL SERVICE 



most affected when the water iu the rivers is highest, usually towards the last of June. 

 Daily fluctuations are largely due to weather changes, more particularly on the direc- 

 tion and velocity of the wind. In the winter the specific gravity is lowered by the 

 flow from the local rivers and streams, depending definitely on the precipitation. 

 Local weather conditions produce fluctuations here as well. 



The variations in the time and the degree of the different phases of the yearly 

 cycle, both as to temperature and to specific gravity, from year to year, evidently have 

 much to do with migration, time of spawning, etc., of many marine animals. 



Explanation of Tables. 



Table I gives the daily mean air temperature records in Centigrade degrees. 



Table II gives the daily records of the surface water temperature taken at the 

 station landing float. Departure bay. 



Table. Ill gives the specific gravity records taken at the same time and place as 

 the temperature records in Table II and reduced to 10 °C. Maximum density of water 

 taken as 10,000. 



The plate includes graphs taken with a ten-day period as a unit, for the five years 

 beginning Jime 1, 191ht, and ending May 31, 1919. 



The upper figure gives the air temperature gi-aph in continuous line and the 

 water temperature graph in dotted line. 



The second figure gives the gi-aph of the specific gravity records. 



The third figure gives the gi*aph of the precipitation in inches. 



The fourth figure (discontinuous) gives a graph of the records of the height of 

 the Fraser river during May, June and July of each year, measured in feet above a 

 zero mark, on Mission bridge. 



TABLE L 

 1914. 



