Evening star., 1925-09-12
ENGLISH CHANNEL
BATTLE OF TIDES
Irregular Bays Make "La
Manche" Full of Tricky
Currents and Vortexes.

when swimmers try to cross the
English Channel they have more than
20 miles Of sea water, the width Of the
Channel at its narrowest point, to
negotiate" says a bulletin from the
Washington headquarters of the Ma
tional Geographic Society. Just to
make the event a sporting one Father
Neptune has assembled in the water
wedge that separates England and the
Continent, a continuous succession Of
tidal streams, cross currents, double
tides, and vorteXes or Whirlpools.
Added to these handicaps are gales in
the Winter and Spring, while fog and
thick weather are common at all
seasons.
England and France have an equal
share in ruling the waves Of what the
English-speaking world calls the Eng
lish Channel and the French call La
Manche' the sleeve). To judge from
the generally agitated character of
its surface the pact is not a peaceful
one. Geography, not stateCraft, is
the cause Of this apparent discord.
SickIe-Shaped Bays.
"Along the south shore Of England,
for the Channel is generally consid-
cred as extending from the Scilly
Islands or Lands End to the Strait of
Dover. is a succession of wide sickle
shaped bays, the shores of which run
north and south, or nearly so, at their
western sides, turning eastward some
what abruptly at their heads. On the
French side the arrangement is re-
versed. The north and south shores
are on the eastern sides Of the bays,
generally speaking, while the gentler
trend is to the west.
These sickle-shaped bays, at ir-
regular angles, twist and retard the
normal tides and currents like battles
in a steam boiler fiue. Tides coming
from the Atlantic are found TO be pro-
gressivelv slower at each headland
until Portland Bill, opposite Cher
| bourg, is reached. From this point
| to Selsey Bill, opposite Havre, there
| are double tides, corresponding to ap-
| proXimately the time of low water in
regular tidal progression. The result
| is two periods Of low water in this
region, separated by slight rise
known as 'gulder.'
ITO compicate matters even more
| the double tide farther east CORE
spends more nearly with high tide,
giving the effect of a prolonged high
| tide in most places. Southampton,
| sheltered behind the Isle of Wight,
has two periods of high tide.
battle-ground of Tides.
|
| of Dover, however, that Neptune puts
| forth his best efforts. To the tidal
| maelstrom of the Channel from the
| Atlantic is added the tidal stream
! from the North Sea. Although the
| time Of their coming together and de-
! parting corresponds roughly, the area
| of meeting and separation is never
| slack. Between Beachy Head and
| North Foreland. and the mouth of
hn TlrnrN rf,-ly
third stream is formed by the two
| tidal currents, known as the inter
| mediate stream. which, running first
| with the Channel stream and then
with the North Sea stream, changes
| its direction throughout its length al
| most simultaneously, a sort of a
water shuttle or friction surface be-
| tween two conflicting sea rivers,
never still.
! 1.-The winds, likewise, have long
| had a powerful effect on the tidal
| streams and currents in this region,
| the latter being in the English Chan
mel simply movements of the surface
| water set up by gales, some far dis
| tant. Often, under the influence of
westerly winds from the Bay of Bis
| cay, new current is set up across
| the entrance of the channel, known
as Rennell's current. Most of the
! time, however, there is a slow and al
most continuous current from west to
| east, perhaps a branch of the Gulf
| Stream through the North Sea.
The latter part of Summer is
! usually chosen by swimmers as the
| best time to make the attempt to
swim the Channel because the tides
are not so strong as during the Spring
| and early Summer and the tempera-
| ture of the water is higher.
Its tides and gales have long given
| the English Channel bad name.
! even among boat passengers. Many
| who have escaped the NAL de mer
| germ on the open sea succumb on the
| 22-mile run between Dover and Calais,
! or the 26-mile run from Folkstone to
| Boulogne, the shortest routes between
! England and the Continent. In Eng
| land 1t is a custom that amounts al
| most to an obligation first to inquire
| of all voyagers arriving from the Con-
| tinent if they have had a pleasant
| crossing"