The evening times. [volume] (Washington, D.C.) 1895-1902, 1901-09-20
OCEAN SURFACE DRIFT.
The Lessons Taught by Hundreds Of
Floating Bottles.

Among the various Investigations car
ried on by the United States Hydro
graphic Office there is one which has al
ways excited greater or less popular in
terest, owing probably 10 the fact that It
lies within the power Of any one who
is at sea. anC who IL likewise gifted with
q reasonable amount Of curiosity and the
leisure time 10 crafty it, 70 contribute
toward the end in view This particular
field Of research is the investigation Of
the surface currents of the sea by means
Of the knowledge obtained through the
drift Of floating bottles. or. as IL Is IA
mIliaTly known, the drift Of bottle pa
pers- The apparatus required IS not eN-
tensive- The date. the latitude and the
Longitude OF the vessel at any given Iimc
aye written upon piece OF paper. this
paper IS placed in an empty bottle Of
whatever character IS nearest 20 hand.
the bottle is then cOrEed and sealed and
cast into the sea. After a lapse Of time.
sometimes Of years, certain OF these bot
ties ind their way 10 the coasts OF the
adjacent continents or Islands. and the
papers contained IL them ultimately r-dc43
the United States photographic Office
Several hundred Of these papers ind
their way back every year, the great MAJ
jOrity OF those which are returned hay
ing been cast adrift in the Atlantic
Ocean. and charts have from year 10 year
appeared showing the drift Of bottles IN
that ocean. These charts all unite in
temperate attitudes of both the North and
South Atlantic. and an equally steady
westerly drift In the tropical attitudes, the
geUeraliZed current system OF either
ocean thus consisting OF q vast eddy about
some central point. the direction OF the
circulation being autI-cycloEic In either
hemisphere that is with the oluTnal mo-
ton Of the sun. as observed IN thaJ heInl-
sphere. lust as in the case Of the pre-
TakSn collectively. the lines Of drift Of
in 81
precisely as in the case Of the Ai-anilc
Ocean that the general direction uf the
drift is eastward in the higher attitudes,
"a ~ wa ri i'm the lower At least this is Sd
for ths. North Pacific For the south Pa
gfdc evidence Of the eastward motion OF
the extratropicaI waters IS lacking None
of the drifts reveal the existence OF the
equatorial cOuuter-current uoWluS east
ward between the westward moving euud-
torial currents Of the southern and north
.ru hemisphereS- The average velocity OF
th- easteTly drIlS IS - mics q uaL- on
the westerly drift 70 miles day, or more
Than rvig, as great. which is again i'm
accordance with the results for the Al
a DerfSctly steady wind acting c5utinu-
ousIy on the surface OF the sea VIII.
through friction. give rise 70
movement Of the surface waters
i'm the same direction as the wind
81 sufficient length of time. the impulse,
Grst felt only al the surface. VIII Er1uu-
IIlV communicate fStil COW inward OWING
O. the viScusity of the water. and the
lower strata 10 Il sUCcessiyeiy greater
and greater depth viii thus psrtake OF the
movement until DO is hUally shared by the
" hole mass the velocity Of the motion di-
niufshinC as the depth Increases.
Perfectly steady winds. however. do not
exist even in the region OF the trades
". have. Therefore. I'm the body CT the
r.r taD distinct sets Of currents. first.
those 40 the immediate surface. which
move practically AT the obedience Of the
surface winds. sometimes in one dirgC-
.lsu. -YurttilutS in another. second. those
" the lower strata. which are constant
il direction and velocity and T,TTcss Mt
the aggregate effect of the Winds that
have blown Tor ages past the sea iu this
respect furnishing close analogy 10 the
atmJ-Eh the motion of the lower Stra-
Ga of which is constantly disturbed. while
that of the higher strata. as shown by
the motion of the cirrus clouds. Is com
Uarauvcly uniform
q is IN, motion If these lower strata,
as ] take IT, that the uniform paths pur-
sued by these drifting bottles To some cE-
tent represent. ana % Is the evidence con
tanned i'm them that should be studied In
Investigations dealing with the currents
OF the ocean in their entirety, rather than
the evidence obtained from any given set
, Of cure MT measurement made at OF near
the surface and for some given point
National Geographic Magazine.