46 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
were then within a few miles of the coast; but they show that the 
temperature remained 60°-61° until 8 a. M., then rose gradually to 
67° at 1 ep. ., July 16, at which time we were in Ipswich Bay. In the 
afternoon we passed into the cold coast water off Portsmouth. The 
air temperature for July 15th shows a rise and fall roughly parallel 
to that of the water, the latter, however lagging far behind the former. 
On the 16th the air temperature rose from 64° at 6 A. M. to 76° at 
11 A. M., 2. e., it was roughly parallel to the rise of the water. 
On August 7th we had a second opportunity to observe diurnal 
warming of the surface. This day was flat calm, with a bright sun, 
but slightly hazy. We ran all day southeastward from Cape Eliza- 
beth. Close to the coast, of course, we passed through the cold band; 
but at 9 A. M. we had run into the warm off-shore water, some fifteen 
miles from the Cape; and air and water temperatures for every hour 
from this point on until midnight are plotted (fig. 5). The surface 
A.M. P.M. 
O. SiG Noi (eR Seals Se 6018 9 1G le? 
bh Ea 
ro A ca BS. 
Sea GR Oe ek 
eT A 
st POP RSE 
0 a SG 
7 eS SE 
pee a Pet ey RO alee 
fA a 
ef OE OW EE 2 
ee ee 
Fic. 5.— Air and surface temperatures, August 7, 1912. 
temperature rose steadily from 60°, until at 1 Pp. M. the maximum, 67°, 
was reached. By this time the air temperature had risen only 1° 
(from 63°-64°); but by 3 p. M., when the water had fallen to 64°, the 
air reached its maximum for the day, 66°. From this time onward 
both air and water cooled, until at midnight both were 61°. This 
case is especially interesting, because the warming of the water pre- 
ceded that of the air, and reached a higher degree. So far as they go, 
these observations show that diurnal warming in the region in question 
is very considerable in clear, calm weather, even as much as 6° or 7°, 
but it is usually much less, 7. e., 2° to 3°. 
