420 
PACIFIC EXPLORATION: G. IV. LITTLEHALES 
tidal observations hitherto gathered on the islands of the Pacific and 
on the coasts of the countries bordering this ocean, the means for the 
construction of the cotidal lines are either wanting or deficient in many 
parts. 
The manuscript sheets of the Bathyraetrical Chart prepared by the 
Hydrographic Office of the Navy Department, containing all the au- 
thentic deep-sea soundings, show the small extent to which the basin has 
been sounded and the distribution of bottom deposits made known, and 
prove the inadequacy of existing measurements to define the general 
contours of configuration. Even the continental shoulder is imperfectly 
known around most of the ocean circuit. In the North Pacific there 
is a tract twice as large as the United States which has been crossed by 
only a single line of bottom soundings about 250 miles apart; and in 
different parts of the Pacific other tracts as large as the continent 
of AustraKa remain entirely unfathomed. The majority of soundings 
are grouped in two lanes running respectively from the United States 
to Australia and from the Hawaiian Islands to the Philippines and 
Japan. No trustworthy contours of equal depth can be drawn 
beyond the continental shelf, because of insufficient information. 
Where knowledge is so imperfect, surprises should be in store for 
those who have accepted the representations appearing in depth- 
maps of the Pacific in which the isobathic contours have been courage- 
ously suppHed. The soundings have generally been spaced too far 
apart to admit of conclusions in relation to even the grosser aspects 
of the orography, and hence the shape of nearly one-half of the earth 
is little known. 
The deposits on the floor of the ocean have been reached at relatively 
few points and have generally been penetrated only to the depth of a 
few inches. The dearth of knowledge of their thickness and strati- 
fication makes it desirable to devise methods of bringing up a core several 
feet long. Although it is extremely doubtful whether these deposits 
have any analogues in the terrestrial rocks, the interest in the evidences 
of their stratification arises on other grounds. For instance, if a layer 
of red clay in great depths should be found overlying a layer of globi- 
gerina ooze, the induction would be that the floor of the ocean at this 
station had once occupied a position at a less depth below the surface 
of the ocean than the one in which the red clay was deposited; and this 
would bear strongly on great problems of crustal deformation. 
The few records of serial temperatures and of the analyses of water 
taken from various depths, show that the Pacific bears a close resem- 
blance to the other oceans in the general distribution of temperature, 
