BIGELOW: EXPLORATIONS OF THE COAST WATERS. 



207 



the whole cohimn), when spring freshening (1914b, p. 401) commences, 

 the surface saHnity diminishing until midsummer (July-August), 

 with a change, in that period of about 2%o. The process is then 

 reversed, the rise being equally rapid at first (August-October), then 

 slower, but uninterrupted, until the maximum is once more attained. 

 In the deep layers the maximum salinity is attained later (August- 



Fig. 42. — Annual range of salinity in the sink off Cape Ann, at location of Station 

 10253, at the surface, 50 meters, 100 meters and 150 meters, (1912-1915). 



September); and the freshening is less and less pronounced as the 

 depth increases, the annual range at 100 meters being only about 

 .7%o- But the water is at its maximum salinity at about the same 

 season, in all depths. 



This region, the only one for which the records cover the entire 

 year, typifies the temperature cycle of the upper layers of the western 



