BIGELOW: EXPLORATIONS IN THE GULF OF MAINE. 71 



was a steady rise in salinity from the surface downward, at all our 

 stations except in the Grand Manan Channel and on German Bank. 

 The bottom salinity below the 100-fathom curve varied from 33.5 to 

 34.54. There is little if any evidence that the wedge of fresh water 

 abreast of Massachusetts Bay, so noticeable from the surface down to 

 fifty fathoms, influenced the bottom water, for the salinity curves at 

 the bottom show very little easterly swing in this region, and that 

 little is probably the result of the bottom contour. The same is true 

 also of the influx from the Penobscot, because the southerly swing of 

 the curve of 33.8 agrees with the bottom contour, following the slope at 

 about the hundred fathom line. It likewise crosses the mouth of 

 Massachusetts Bay at one hundred and twenty fathoms, rising to about 

 eighty-five fathoms off the northern end of Cape Cod. But it does not 

 enter the trough west of Jeffrey's Ledge, for here the salinity of the 

 bottom water in sixty to eighty fathoms is only 33 to 33.2. North- 

 eastward from Jeffrey's Bank the 33 curve rises higher and higher on 

 the coastal slope until finally water of this salinity was found at about 

 fifty-five fathoms off Petit Manan. The curve must then turn off- 

 shore, for the bottom water in the Grand Manan Channel was only 

 about 32.5-32.6. No station was made on Grand Manan Bank; 

 but judging from conditions on the other banks, it is not likely that 

 the bottom water had a salinity as high as 33. The same is also 

 true of Lurcher Shoal. On German Bank, also, the bottom water was 

 fresher, only 32.9 in thirty-five fathoms; hence it is probable that 

 the 32.6 curve came close to the surface along the west coast of Nova 

 Scotia. The bottom salinity of Piatt's Bank was above 32.5; and 

 it is probable that this was the case on Cashe's Ledge likewise. On 

 the other hand the circumscribed deep basin in the mouth of Massa- 

 chusetts Bay (Station 2) had a considerably lower bottom salinity, 

 32.92, than the waters at corresponding depths further east. Over the 

 eastern arm of the 100-fathom basin the bottom salinity was 34 or 

 over, the highest values being at Station 28, 34.5; Station 32, 34.1; 

 and Station 36, 34.3, in one hundred and twenty, ninety, and one 

 hundred fathoms respectively. But at Station 27, only a few miles 

 west of the saltest spot, the bottom salinity at 100 fathoms was only 

 33.9. 



Salinity profiles. — The profiles (fig. 29-33) can not pretend to 

 as great accuracy as those for temperature, because the number of 

 observations is much smaller; and they are necessarily largely recon- 

 structed from the salinity sections. But if regarded only as prelimi- 

 nary, they are useful as showing general distribution of salinity. 



