CHAP. VIII. ] THE GULF-STREAM. 357 
the eastern Border of the North Atlantic fringing 
Western Europe. A small but very interesting por- 
tion of it forms the channel between the Féroe 
Islands and the North of Scotland, one of the chan- 
nels of communication between the North Atlantic 
and the North Sea; and a few soundings in shallow 
water to the east of Shetland are in the shallow 
North Sea basin. It is evident, therefore, that the 
greater part if not the whole of this belt must par- 
ticipate in the general scheme of distribution of 
temperature in the North Atlantic, and must owe 
any peculiarities which its thermal conditions may 
present to some very general cause. 
All our temperature observations, except the few 
taken in the ‘ Lightning’ in 1868, were made with 
thermometers protected from pressure on Professor 
Miller’s plan, and the thermometers were individually 
tested by Captain Davis at pressures rising to about 
three tons to the square inch before they were fur- 
nished to the vessel; they were also more than once 
reduced to the freezing-point during the voyage to 
ascertain that the glass had been in no way iieiaaee 
The results may therefore be received with absolute 
reliance within the limits of error of observation, 
which were reduced to a minimum by the care of 
Captain Calver. 
A large number of scattered observations, most 
of which have unfortunately been made with instru- 
ments which cannot thoroughly be depended upon 
for accuracy of detail,—the error, liowever, being 
probably in the direction of excess of heat,—esta- 
blished the singular fact that although the tempera- 
ture of the surface of the sea in equatorial regions 
