ÖÖI 8x 3 ^c- 0 - Acehbooks.org

S U M A T R A . 17
The periodical winds which are fuppofed to blow during fix months
from the N. W. and as many from the S. E. rarely obferve this regularity,
except in the very heart of the monfoon ; inclining, almoft at all
times, feveral points to feaward, and not unfrequently blowing from
the S. W. or in a line perpendicular to the coaft. This muft be attributed
to the influence of that principle which caufes the land and fea
winds, proving on thefe occafions more powerful than the principle of
the periodical winds ; which two always act at right angles with each
other. If thefe were of equal power, the current of air would take a
middle direction, and conftantly blow, on Sumatra, from the W. point,
during one monfoon, and from the S. point during the other :—and as
the influence of either is prevalent, the winds approach to a courfe perpendicular
to, or parallel with the line of the Coaft. The tendency of
the land wind at night, has almoft ever a correfpondence with the fea
wind of the preceding or following day; (except when a fquall or other
fudden alteration of weather, to which thefe climates are particularly
liable, produces an irregularity) ; not blowing in a direction immediately
oppofite to it; which would be the cafe, if the former were, as fome
writers have fuppofed, merely the effect of the accumulation and redundance
of the latter, without any pofitive caufe; but forming an equal
and contiguous angle, of which the coaft is the common fide. Thus,
if the coaft be conceived to run N. and S. the fame influence, or combination
of influences, which produce a fea wind at N. W. produce
a land wind at N. E. or adapting the cafe to Sumatra, which lies
N. W. and S. E., a fea wind at S. is preceded or followed by a land
wind at E. This remark muft not be taken in too ftridt a fenfe, but
only as the refult of general obfervation. If the land wind, in the coürfe
of the night, (hould draw round from E. to N. it would be looked upon
as an infallible prognoftic of a W. or N. W. wind the next day. On
this principle it is, that the natives foretell the direction of the wind,
by the noife of the furf at night, which if heard from the northward,
is efteemed the forerunner of a northerly wind, and vice verfd. The
quarter from which the noife is heard, depends upon the courfe of the
land wind, which brings the found with it, and drowns it to lee-
F ward—