598 
BULLETIN OF THE BUBEAU OF FISHEBIES 
uppermost stratum, 5 to 10 meters thick, was then nearly homogeneous in tempera- 
ture at several of the stations closest to the land. Although the precise rate of ver- 
tical cooling varies from station to station even over the small area of Massachusetts 
Bay, the surface temperature of its whole area usually warms upward of 10° above 
that of the 20 to 50 meter level by the end of the summer. 
Serials have also yielded curves of this same general type in the west-central 
parts of the basin, generally, and in the northwestern part of the gulf between the 
latitudes of Cape Ann and of Cape Elizabeth during July and August. 
Temperature, Centigrade 
Fig. 49.— Vertical distribution of temperature at successive stations, from Cape Ann to Grand 
Manan, in July and August, 1912. A, near tbe Isles of Shoals, July 17 (station 10011); B, 
off Cape Elizabeth, July 29 (station 10019); C, off Penobscot Bay, August 22 (station 10039); 
D, off the western entrance to the Grand Manan Channel, August 19 (station 10035) 
Our first summer’s cruise (Bigelow, 1914, p. 51), however, proved that the dif- 
ference of temperature between the surface and the underlying water (which is nearly 
uniform, depth for depth, from Cape Ann to Platts Bank) decreases along the coast 
to the eastward (fig. 49). Observations taken in the summers of 1914, 1915, and 
subsequently have not afforded a single exception to the rule (stated in Bigelow, 1917, 
p. 168) that the surface temperature is progressively lower and lower in summer, the 
