390 



bulletin: museum of compaeative zoology. 



was occupied in 20 fathoms of water some three miles off Gloucester. 

 The surface temperature had now dropped to 40.5° and at 19 fathoms 

 to 41.7°, i. e., we found the reversal of temperature foreshadowed on 

 the last visit, which* was to be a constant phenomenon from this time 

 on until spring. The salinity at 19 fathoms proved to be practically 

 the same as at the last station (32.8%c); but at the surface it had 

 fallen to 32.56%o, no doubt as the result of a snow-fall of three inches 



Fig. 3. — Surface Temperature - 



— , off Cape Ann and Gloucester, 



November 20 to April 13; and surface salinity , off Cape Ann , 



November 20 to April 3. 



on the previous day. Owing to the comparatively fresh surface, the 

 water was now temporarily in stable equilibrium, in spite of the fact 

 that it was coldest at the surface, the density being 25.77 at the 

 surface, 25.98 at 19 fathoms. After completing the station we ran 

 through Squam River to Ipswich Bay, where, sheltered from the 

 wind, we made a station for the sake of comparison with the waters 

 on the south side of Cape Ann. The surface water proved to be 

 considerably colder here, 40.3°, with 40.7° at 8 fathoms. But at 18 



