28 
ATOLLS. 
Ch. I. 
group, appears to be sixty miles long and twenty broad. 
Most of the atolls in this group are of an elongated 
form ; thus Bow Island is thirty miles in length, and 
on an average only six in width (See Fig. 4, Plate I.), 
and Clermont Tonnere has nearly the same proportions. 
In the Marshall Archipelago (the Balick and Badack 
group of Kotzebue) several of the atolls are more than 
thirty miles in length, and Bimsky Korsacofif is fifty- 
four long, and twenty wide at the broadest part of its 
irregular outline. Most of the atolls in the Maldiva 
Archipelago are of great size, one of them (which, how- 
ever, bears a double name), measured in a medial and 
slightly curved line, is no less than eighty-eight geo- 
graphical miles long, its greatest width being under 
twenty, and its least only nine and a half miles. Some 
atolls have spurs projecting from them ; and in the 
Marshall group there are atolls united together by 
linear reefs, for instance Menchioff Island (See Pig. 3, 
Plate II.), which is sixty miles in length, and consists 
of three loops tied together. In far the greater num- 
ber of cases an atoll consists of a simple elongated ring, 
with its outline moderately regular. 
The average width of the annular reef may be taken 
at about a quarter of a mile. Capt. Beechey 1 says 
that irwthe atolls of the Low Archipelago it exceeded 
in no instance half a mile. The description given of 
the structure and proportional dimensions of the reef 
and islands of Keeling atoll, appears to apply perfectly 
to nearly all the atolls in the Pacific and Indian 
1 Beechey’s Voyage to the Pacific and Behring’s Straits, chap. viii. 
