94 bulletin: museum of compakative zoology. 



we got a bottom reading of 39.2°. In the deep basin off Cape Ann, 

 Verrill's readings, in ninety, one hundred and eighteen and one hun- 

 dred and fourteen fathoms, are 40°, 43°, 39° and 39°, at three stations 

 near together. But the fact that we found a thick layer of bottom 

 water very uniform in temperature in this region, suggests that the 

 discrepancy in his readings was due to the faulty instruments. And 

 it is at least suggestive that the average of his four readings in the 

 basin is 40.2°, i. c, within .1° of our observations. Off Cape Cod, 

 too, in 142 fathoms, close to Station 43, the bottom temperature in 

 1874 was 39° or 42°, agreeing fairly well with our record of 41.3° at 

 Station 43. And the difference in depth is not significant in this 

 case, because we encountered the uniform bottom water at 50 

 fathoms. On the other hand Verrill records a bottom temperature 

 of 52° in 100 fathoms southwest of Jeffrey's Bank, where in 1912 the 

 bottom reading, to judge from neighboring stations, must have been 

 little, if any above 40.3°. And our entire experience makes it so 

 improbable that the 100 fathom temperature is as high as 50° anywhere 

 in the Gulf, that such a reading is best credited to the unreliability 

 of the instrument with which it was taken. On the whole the bottom 

 temperatures in Massachusetts Bay, in the western basin, and in 

 the trough west of Jeffrey's Ledge were practically the same in 1873 

 as they were in 1912. But Verrill's readings for the northeast corner 

 of the Gulf are so consistently lower than ours, that it is probable that 

 the bottom water in that region actually was from 1° to 3° colder in 

 1873 and 1874 than it was in 1912. His records for 1874, (1875, 

 p. 413) agree in a general way with our work in 1912, but as the 

 same imreliable thermometers were used, and only one reading taken 

 at each station, it is unwise to lay stress on them. 



Dickson's, (1901) charts show the salinity of the eastern half of the 

 Gulf as below 32%o the Bay of Fundy 31%o or lower, and Massachu- 

 setts Bay as below 32 for August, 1897 (no salinities are given for the 

 remainder of the Gulf for these months). But on examining his 

 tables, which give the tests of the water samples on which the charts 

 are based, I did not find a single record from within the Gulf for either 

 month, which suggests that the salinity credited in his charts to the 

 eastern half of the Gulf was deduced from the low salinities revealed 

 by several water samples taken in that month off the Nova Scotian 

 Coast. But our own records show that his reconstruction of this 

 region was probably incorrect, because it is certain that in August, 

 1912, there was an indraught of Atlantic water with salinities of 32.8 

 or more into the eastern part of the Gulf, and we have no actual data 



