Portland Lightship (Figure 3, Table 3) 
Surface temperatures from May through August, 1957, were well 
above the 1956 readings and above the mean for 197-1956, except for a 
drop during the first 10 days of July. After September, however, they 
fell below both the mean and the 1956 values. 
Minimum temperatures of less than 38° occurred in March, and 
were some two degrees warmer than the 1956 minimum. The thermocline be= 
gan to develop in mid-April and reached a maximum in early August with 
surface temperatures above 60°F, more than 2 degrees warmer than the 
1956 maximum; bottom maximum was greater than \8°F in late August. By 
mid-November the thermocline had been destroyed, the water becoming iso- 
thermal at 6°. Chilling continued more rapidly during December than it 
had the year before. 
Surface salinities were uniformly higher throughout the year 
than the comparable 1956 values and showed less fluctuation. The mini- 
mum in terms of 10 day means was 31.6 °/oo and occurred in late May; 
the 1956 minimum was less than 29 °/oo in early May. Highest surface 
salinities, just under 33 °/oo,appeared in February and again in Decem- 
ber. 
Bottom salinities ranged from slightly above 33 °/oo in Feb-= 
ruary and again in the late fall to less than 31.) °/oo in July. There 
was less difference between surface and bottom salinities in 1957 than 
there had been the previous year. 
