BIGELOW: COAST WATER EXPLORATION OF 1913. 245 



terranean and in the Red Sea, and a similar error runs through Libbey's 

 whole series of subsurface densities. As just pointed out it can not 

 be charged to the instruments, and in absence of information as to how 

 soon the observations were made after the samples were collected, 

 there is no means of judging whether it can be laid to evaporation of 

 the samples. But whatever its origin, it is useless to attempt any 

 reconstruction of the density curves along his profiles. Had this been 

 possible, it would have thrown light on the origin of the cold tongue 

 which Libbey suspected was a "mechanical intrusion of cold water 

 from the surface of the continental platform, reinforced by the specific 

 gravity of the water" (1891, p. 407), as was certainly the case in 1913. 

 In the neighborhood of Woods Hole, Sumner, Osburn, and Cole 

 (1913) took a considerable series of hydrometer readings, checking 

 them from time to time by titration. And though from their very 

 nature they can not claim the accuracy of the latter method, yet their 

 averages must be very close to the truth. They found the mean 

 salinity of Vineyard Sound in July and August about 32.2%o which 

 agrees very well with our record of 32.29%o off the entrance to Vine- 

 yard Sound (Station 10084). Dickson's (1901) charts show the water 

 immediately south of Marthas Vineyard as 32%o in July, 1897, with 

 the salinity 33%o and higher over the 100 fathom contour. In 

 August of the same year, the coast water between Delaware Bay and 

 Nantucket Shoals was below 32%o bounded seaward by a zone of 

 water with salinity between 32%o and 33%o over the outer part of 

 the continental shelf. These charts, taken at their face value, sug- 

 gest that the salinity was considerably lower in 1897 than in 1913, for 

 in July of the latter year water fresher than 32%o was confined to a 

 small area off the mouth of the Hudson River, and along the south 

 shore of Long Island. But the records on which they are based are 

 so few that it is a question whether there actually was any such 

 difference between the two years. And Schott represents the salinity 

 of the water over the continental shelf between Cape Cod and Chesa- 

 peake Bay as 32-33%o (1902, taf . 33) . Further information as to the 

 salinity of our coastal zone is contained in the Bulletins of the Inter- 

 national Conseil for the exploration of the sea. In August, 1907, 

 and February, 1908 (1909), the water along the coast of Nova Scotia 

 was 32%o or less; the curve for 32%o touching Cape Cod in the latter 

 month. And the curves for May of that year afford the interesting 

 information that 32%o water spread seaward in an obtuse wedge, 

 abreast of the Gulf of Maine, and that water of that same salinity 

 bathed the coast as far as New York. Unfortunately there were no 



