The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1896-07-09
TIDES OF SOUTH SEAS.
photographic Reports From Data
Collected by L. ). Government.

: The United States photographic Of
fee has turned its attention 10 ocean
, currents. The pilot chart for June is
one of the best of the issue, and marks
} the erratic courses of tides that ebb and
flow in the calm waters of the South
Seas.
The phenomena of the tides is partic-
ularly noticeable in the Southern At
Iantic and Pacific. It becomes apparent
that there exists in each certain nor
NAL or typical condition which these
currents tend TO assume. but which is
only attained at long intervals. and then
for very brief periods, the approach of
this ideal form being in general closest
during the month of June, Of which
month it is also true that the condition
| of atmospheric equilibrium most near
~ prevails
| Confining the attention to the portion
| of these oceans which lie near the equa-
| tor on opposite sides of the zone of
Gains flow westerly the waters of the
north and south equatorial currents re-
spectiveIy, each due 20 the persistent
action of the trade winds in its proper
hemisphere, and in a general manner
agreeing with the region over which
these winds prevail. In both oceans the
southern equatorial current is far more
powerful, not only in width but also in
velocity. In the Pacific it may be said
to extend from II deg. S. to deg. N,
the belt of maximum velocity being its
northern edge and extending in an un-
broken line from the Galapagos Islands
TO the Island of New Guinea.
In crossing this belt vessels have ex-
perienced a westward set of 100 miles |
from noon to noon. Going southwark
this velocity falls off rapidly, until at
the same distance south of the equator
that the first is to the north second |
belt of high velocity is attained, eX- |
tending along the parallel of deg. S., |
especially between the meridians of 100 |
deg. and 140 deg. w. Brought to the
surface by the action of the equatorial |
current, the colder water of the depths |
of the ocean spreads westward from |
the coast of South America along the |
equator in a narrow strip as far as the |
10th meridian, the surface tempera- |
ture during the autumn season increas- |
ing by as much as so to 10 deg. Fair. as
we pass from the equator to 10 deg. S. |
latitude along this meridian. This cold |
er water is of dark green color, readi-
ly distinguishable from the dark blue |
of the warmer water of the equatorial |
counter current Immediately to the |
northward. Westward of 140 deg. the |
southern equatorial current takes |
course slightly south of west, just as
the trades in this region blow from |
point rather to the north of east Pass
ing the 180th meridian, the true course
is again resumed, and the main body of /
the drift sweeps by the north shore of /
New Guinea with increased velocity. |
and recurves into the equatorial counter
current
The northern equatorial current is
included in zone extending from
deg. north to 20 deg. north. It attains
velocity about half that of it's great |
southern counterpart, and it fails to
show the existence of any well defined !
axis or line Of greatest velocity It's
strength, however, does not diminish
as we go westward but rather increases
again, showing an analogy with the
trades. One great arm of the current
sweeps nOrthward past the Philippine
Islands, and thence into the northern
region of the Pacific, as the Kuro Sivo.
The waters Of the other branch recurve
and unite with those of the south equa-
torial current
The equatorial counter current is of
special interest. 1t owes it's origin to
no prevailing winds, but simply to the
tendency of the waters heaped I'D on
the shores of Asia and Australasia by
the action of the trades to return to a
condition OF equilibrium. From July to
December it receives at it's western ex-
tremity the assistance of the the south
west monsoon, and likewise, after pass
Ing IN It's eastern course the 150th me-
rldIan, 1t is favored by the southwest
winds which prevail in the region of
Gains from July to October, and at this
time and in this place it attains it's
maximum velocity and extent But even
after these winds have ceased, it's DOW
er shows no considerable diminution.
for the current is now reinforced by
the continued activity of the north
equatorial current in consequence of
the increased strength of the northeast
trades
AS shown upon the pilot chart for
February, during the winter season
the equatorial limits of the trades an
proach each other so closely as to cross.
During this season, long continued and
steady easterly winds sometimes sue
ceed IN weakening and even reversing
the current; but whenever and wher-
ever the wind lightens in force. or hauIs
to slightly less unfavorabIe direction.
the current at once reasserts itself. and
at times with great strength. The as
sertion so often made, that the north
and south equatorial currents come in
contact with each other is not justified.
It is computed that the distance ira