590 
BULLETIN OF THE BUREAU OF FISHERIES 
local variation as the tide swirls around the islands and ledges. The maximum tem- 
peratures at Seguin Island Lighthouse for the .years 1881 to 1885 (Rathbun, 1887), 
were, respectively, 13.3° to 13.9°. 13.3° to 13.9°, 13.9° to 14.4°, 13.9° to 14.4°, and 
14.4°. This agrees with readings of 13.9° at two localities within a few miles of the 
island on August 22, 1912, and with 12.8° to 14° in that general neighborhood on July 
18, 1925; but one need run only a few miles offshore from this part of the coast to fin d 
the surface warmer than 16°, and Doctor Kendall records a reading of 16.7° within 
about 8 miles of the land off Seguin on August 16, 1897. 
The surface temperature rises to 16° to 18° in Boothbay Harbor during the last 
week of July and the month of August (fig. 30); equally high, no doubt, in other 
sheltered bays in this neighborhood. 
Surface readings taken on a line across the mouth of Penobscot Bay ranged from 
12.8° to 13.9° on August 21, 1912, while Rathbun (1887) gives maximum tempera- 
tures of 11.7° to 12.2° at the lighthouse on Matinicus Rock at the western gateway 
to the bay, where the water may be somewhat chilled by the swirling tidal currents. 
The surface in sheltered situations within Penobscot Bay may warm to a tempera- 
ture several degrees higher than this before autumnal cooling sets in, but infor- 
mation is scant for this particular region. 
Our surface readings among the outer islands along the coast of Maine, east of 
Penobscot Bay, and out to the 100-meter contour usually have ranged between 10° 
and 12° for the last half of July and for the month of August (fig. 47). After a 
few calm, warm days the temperature of this zone may rise locally to 13° (12.78° 
off Mount Desert Island, August 13, 1913, station 10099, has been our highest record 
there). The surface water is considerably warmer up the bays, locally, depending 
on the topography of the bottom as determining how actively the water is stirred by 
the tide, and especially on the extent of the flats laid bare to the sun on the ebb. 
Surface readings of 10.6° to 11.7°, recorded by the Halcyon within a mile or two of 
Great Duck and Little Duck Islands, Bakers Island, and Long Island on August 8 to 
11, 1925, cover the usual midsummer range close in to the islands and among them 
for the Mount Desert region. 
Rathbun (1887) gives maximum summer temperatures of 11.6° to 13.3° at Petit 
Manan light, and although the surface water off Machias was only 8.9° on July 15, 
1915 (station 10301), probably it is always as warm as 10°, or warmer, there during 
the last half of August, and usually 11° to 12°, except where some local upwelling is 
taking place. 
The hourly temperatures taken off the eastern coast of Maine during the last half 
of August, 1912, are especially interesting because they suggest a movement of the 
coldest surface water (colder than 13.5°) offshore (i. e., to the southwest), out past 
Mount Desert Rock (fig. 47) . Unfortunately I can not state whether this phenom- 
enon is regularly recurrent in summer; but the fact that the surface was slightly 
cooler (9.3°) near Mount Desert Rock on September 15, 1915, than close in to Mount 
Desert Island (9.8° to 10.8°), near Petit Manan Island a few miles eastward along 
the coast (10.5°), or near Swans Island to the westward (10.8°), suggests that some 
such distribution of surface temperature is at least not unusual for that general 
region. 
