150 The Tides in South Pacific. 
Tahitian group comprises the whole of the South Sea Islands 
to which his remarks extend. In his observations on the 
tides, he says, ‘‘ Among the natural phenomena of the South 
Sea Islands, the tide is one of the most singular, and pre- 
sents as great an exception to the theory of Sir Isaac Newton 
as is to be met with in any part of the world. The rising 
and falling of the waters of the ocean appear, if influenced 
at all, to be so in a small degree only by the moon.” 
When others have contented themselves in merely giving 
their observations, without attempting to account for the 
diversity, I can hardly venture a single suggestion to solve 
the difficulty. 
If Professor Whewell’s Map of Co-Tidal Lines be correct, 
the tide travels, on the western coast of America, from north 
to south, between Acapulco and the Straits of Magellan; 
while, from the former, it travels northward and westward. 
The first, most likely, moves south, until it meets with the 
great tidal oscillation, which proceeds with great rapidity, in 
a westerly direction, round Cape Horn. There is, then, no 
difficulty in conceiving, that between these two great tidal 
waves, running in an ellipsis to the westward, the Society 
Islands are left in the intervening space, or what a Scotch- 
man would call the “strath,’’ unaffected by either of these 
waves, but still subject to the solar oscillation, which may 
form apart from that of the lunar. The tide-waye on the — 
north will be inclined to the south, according to the moon’s 
excursions in declination or southing; and this may account 
for the diversity at times, as already observed, of high-water 
being frequently an hour before or after noon, just as the 
base of the lunar wave may advance more or less to the south, 
by the moon’s declination and parallax. 
Peculiarities of tides, though of a different kind, are to 
be observed in many places. Professor Whewell mentions 
that about the Ower Shoal, the whole rise of the tide occurs 
in about three hours. In the Frith of Forth, it has been 
observed at times, that after the tide has begun to ebb, 
another rise takes place, though small in comparison with 
the first ; so that, in fact, there are two larger and two smaller 
tides in the twenty-four hours. 
