PHYSICAL OCEANOGRAPHY OF THE GULF OF MAINE 627 



of the gulf was slightly colder, the western half slightly warmer, in the summer of 

 1913 than in 1912, though the greatest annual difference was nowhere greater than 

 2.5° for sets of observations taken at nearly the same date. Thus we found the 

 August stations in Massachusetts Bay agreeing very closely for these two years 

 (stations 10044, 10045, and 10106). The water a few miles north of Cape Ann was 

 about 1° to 2.5° warmer in August, 1913 (stations 10104 and 10105) than in 

 July, 1912 (stations 10011 and 10012b), a difference that may have been due chiefly 

 to a difference in the dates at which the readings were taken. 



The surface of the western side of the basin was about 1° warmer, the 100-meter 

 level about 0.5° warmer, and the 200-meter level about 1.5° warmer on August 9, 

 1913 (station 10088), than on July 15, 1912 (station 10007); and while this differ- 

 ence was seasonal in the shoal strata, it probably reflected an annual fluctuation at 

 depths greater than 100 meters. Off' Platts Bank, a few miles to the northward, 

 observations taken within three days of the same date (7th of August in 1912, 

 station 10023; August 10 in 1913, station 10091) showed the immediate surface 

 about 1° colder in 1913 than in 1912. However, this may have been due to a differ- 

 ence in the stage of the tide, which runs strong over the bank. The bottom tem- 

 peratures there were almost precisely alike for the two years. In the eastern side 

 of the basin 1913 was slightly the warmer year down to 70-odd meters, but about 

 1.5° the colder from that level down to bottom at stations only a few days apart in 

 date. 



The fact that the water was more than 2.5° warmer on the surface near Monhe- 

 gan Island on August 14, 1913 (station 10102), than on August 2, 1912 (station 

 10021), though with virtuafly no difference below the 30-meter level, can hardly be 

 accounted for on a seasonal basis. The mean temperature for the whole column of 

 water was also about 0.7° higher on Jeffreys Bank, off Penobscot Bay, on August 2, 

 1913 (station 10091, about 10°), than on the 8th in 1912 (station 10025, about 9.3°), 

 with less active vertical circulation, as evidenced by a wider vertical range of temper- 

 ature. The 1913 temperatures, however, were about 0.75° to 1.5° the lower a few 

 miles farther east on August 14 (station 10038, 1912; station 10101, 1913). The 

 August temperatures for 1913 were likewise 1° to 1.5° the colder along the eastern 

 coast of Maine and over the coastal bank west of Nova Scotia, where the obser- 

 vations for the two years were taken within a few days of the same dates. For 

 example, the station off Lurcher Shoal was about 1° colder at the surface and in 

 the mid levels, about 2° to 3° colder near bottom at 120 to 140 meters depth, in 

 1913 (station 10096) than in 1912 (station 10031); German Bank was also about 2° 

 colder at all -levels. 



Except for the immediate surface, so subject to seasonal change, the upper 100 

 meters of the western basin was warmer in 1915 than in any previous summer of 

 record; below that depth the readings for that year were fractionally cooler than 

 those for 1913 or 1914, but warmer than for 1912, with an extreme annual variation 

 of about 2.4°. 



The surface stratum of the center of the gulf near Cashes Ledge was 2° to 3° 

 warmer in 1914 than in 1913, but the water deeper than 40 meters was as much 

 colder, with temperatures for 1915 intermediate between these two years at depths 



