54 EXPLOEATIONS, WESTERN ATLANTIC, STEAMER BACHE, 1914. 



Only off Chesapeake Bay is the actual density of the mixed water 

 known for winter. But inasmuch as winter cooling, off our coasts, is 

 most rapid and most extreme next the land (Bigelow, 1915), while the 

 salinity of the coast water, so far as known, rises during autumn and 

 winter (Bigelow, 1915), it follows that the mixed is heavier than ocean 

 water in winter all along our coast, as it certainly is off Chesapeake 

 Bay (p. 49). 



But while the actual occurrence of a downpour over the slope can 

 be considered as demonstrated off Chesapeake Bay in winter, and 

 off Georges Bank in summer, our summer profiles across the shelf 

 at intermediate points would be hard to reconcile with this type 

 of vertical circulation (Bigelow, 1915). It is possible that a local 



FiQ. 53.— Density sections in the ocean water {Baclit station 10161), and in the mixed water {BacU station 

 10158), off Chesapeake Bay, January, 1914, and in the mixed water {Grampus station 10171), off Delaware 

 Bay, July, 1913. 



dynamic tendency of this sort might be overridden by some more 

 wide-spread type of oceanic circulation. But whether the down- 

 pour be general for the zone over the continental slope, or only 

 local or temporary, the fact that it actually occurs is one of the most 

 interesting hydrographic results of the cruise of the Bache, for when- 

 ever anything of the sort takes place the mixed water must play as 

 important a r61e in the manufacture of the deeper layers of the coast 

 water on the shelf as it does in the Gulf of Maine. 



Finally, it is shown that there is nothing in the Bache or Roosevelt 

 temperatures to suggest the ''Arctic" current so often invoked off our 

 coasts (Bigelow, 1915), the coast water being far too warm even in 

 January. 



