BIGELOW: EXPLORATIONS OF THE COAST WATERS. 



203 



tween Gulf Stream and mixed water diminishes, until at and Ijelow 

 200 meters, it is of doubtful validity. 



The density at 100 meters, at which level the Gulf is practically an 

 enclosed estuary (Fig. 39), is particularly instructive for its bearing 

 on circulation (p. 239) ; for it not only shows this dense water (1 .027+ ) 

 separating the lighter Gulf Stream water from the slope in a triangle 

 constantly widening from Station 10218 eastward, but reveals an 

 equally dense tongue filling the Eastern Channel, and extending thence 

 (Station 10225) northward into the Eastern Basin, while a second 



Fig. 40.— Diagram showing the surface current, at Station 10231, from 2.30 A. M. 

 to 2 P. M. The distances between the dots give the drift. 1.5 cm. = 1 sea mile. 

 The compass arrows are true and magnetic: variation about 19° W. 



dense tongue (27+) approaches the land off Halifax, corresponding 

 to the high salinity there (197). The intrusion of dense water into 

 the Gulf via the Eastern Channel is equally evident down to about 

 200 meters; but below this level it is barred from the Eastern Basin 

 by the ridge which encloses the latter on the south (Plate 2). 



Current Measurements. — The Ekman current-meter was used at 

 one Station (10231) in 1914, off Shelburne, where measurements were 

 taken at a depth of 3 fathoms, hourly for twelve hours, to cover an 



