TOPOGRAPHY. Q1 
characteristics of the great chains, bearing upon their courses, and 
the relations of the two systems of ranges. 
I. The ranges, when viewed as a whole, are generally more or less 
curved. 
a. The Hawaiian chain has a slight curve, with the convexity 
northward, the western extremity of the range becoming a little more 
westerly in its course. 
6. The Samoan chain is a striking example of a curved course. 
The trend becomes more and more northerly on going westward, as 
the following measured courses show :—Atiu range extends N. 66° W.; 
Samoa, N. 68° W.; Vaitupu, N. 56° W.; Tarawan, N. 42° W.; Mar- 
shall Groups, N. 35° W. 
c. The Ladrones have a slight curve, the northern islands becoming 
more northerly, as already stated. 
d. The Salomon range curves very decidedly, the northwest course 
changing gradually, and approaching east and west; the New Hebrides 
trending N. 40° W.; Vanikoro, N. 44° W.; the Salomon Islands, 
N. 57° W.; New Ireland, N. 65° W.; Admiralty Islands, N. 85° W. 
e. The New Caledonia range curves nearly parallel with the pre- 
ceding, New Caledonia trending N. 40° W.; Louisiade, N. 56° W.; 
New Guinea, (north coast,) N. 65° W.; and the west extremity be- 
coming still more westerly, or N. 82° W., as nearly as can be esti- 
mated. 
The line of Java and Flores, we thus perceive, is part of the same 
system; for the northwest course falls imperceptibly into the east 
and west, through the Salomon and New Caledonia ranges. Again, 
farther west, the line rises as gradually to a northwest course, through 
Java and Sumatra. 
The courses of all the ranges are marked upon the chart. The 
anomaly of an east-and-west trend in the southern part of the Hast 
Indies appears, therefore, to be but an example of a modification in 
direction, which the northwest system may undergo. A thorough 
examination of the relative positions of the groups in the Southwest 
Pacific only confirms this conclusion, as will appear from the follow- 
ing facts. 
Il. The transverse trend varies in its direction nith the northwest 
trend, so as to be in each case nearly at right angles with the latter. 
a. In the East Indies, the Sumatra range, which is continued, as 
we have suggested, by Java and the south of New Guinea, (and _pos- 
sibly by Flinders Island, North New Zealand to Chatham Island,) 
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