Alternate tides in sacred order run.—BLACKMORE.
Among the most wonderful phenomena of nature may be reckoned the tides
of the sea. They were but little understood by the ancients, although
Pliny, Ptolemy and Macrobius, were of opinion that they were influenced
by the sun and moon. The former expressly says, that the cause of the
ebb and flow is in the sun, which attracts the waters of the ocean; and
he adds, that the waters rise in proportion to the proximity of the moon
to the earth.
The phenomena of the tides have been ascribed to the principle of innate
gravitation; but Sir Richard Phillips, in his theory of the system of
the universe, refers them to that general law of motion which he
considers as the primary and proximate cause of all phenomena,
operating, in a descending series, from the rotation of the sun round
the fulcrum of the solar system, to the fall of an apple to the earth.
This motion being transferred through all nature from its source, serves
as the efficient cause of every species of vitality, of every organic
arrangement, and of all those accidents of body heretofore ascribed to
attraction.
The waters of the ocean are observed to flow and rise twice a day, in
which motion, or flux, which in the same direction lasts nearly six
hours, the sea gradually swells, and, entering the mouths of rivers,
drives back the river-waters toward their head. After a continued flux
of six hours, it seems to repose for a quarter of an hour, and then
begins to ebb, or retire back, for six hours more; in which time, by the
subsidence of the waters, the rivers resume their usual course. After a
quarter of an hour, the sea again flows and rises as before.
According to the theory of Newton, these phenomena were supposed to be
produced by an imaginary power called attraction. The moon was supposed
to attract the waters by the influence of an occult power inherent in
all matter; just as the earth was supposed to attract the moon, the moon
the earth, and the planets one another. Others, again, ridicule this
idea, as unsustained and visionary, giving in their turn some theory
that has no better argument to sustain it. And it is probable the time
is yet future when we shall have any theory that will fully account for
all the phenomena of the tides. On account of the shallowness of some
seas, and the narrowness of the straits in others, there arises a great
diversity in the phenomena, only to be accounted for by an exact
knowledge of the place. For instance, in the English channel and the
German ocean, the tide is found to flow strongest in those places that
are narrowest, the same quantity of water being, in this case, driven
through a smaller passage. It is often seen, therefore, rushing through
a strait with great force, and considerably raised, by its rapidity,
above that part of the ocean through which it runs.
The shallowness and narrowness of many parts of the sea, give rise also
to a peculiarity in the tides of some parts of the world: for in many
places, in the British seas in particular, the greatest swell of the
tide is not while the moon is in its meridian hight, and directly over
the place, but some time after it has declined thence. The sea, in this
case, being obstructed, pursues the moon with what dispatch it can, but
does not arrive with all its waters, until after the moon has ceased to
operate. Lastly, from this shallowness of the sea, and from its being
obstructed by shoals and straits, it happens that the Mediterranean, the
Baltic and the Black sea, have not any sensible tides, to raise or
depress them in a considerable degree.
Among the phenomena of the tides, one of the most singular is the bore,
peculiar to several rivers: it is ascribed to the waters, which were
before expansive, being suddenly pent up, and confined within a narrow
space. This bore or impetuous rush of waters, accompanies the first
flowing of the tide in the Ferret, in Somersetshire, and in the Seine,
in France. It is also one of the peculiarities of the Severn, the most
rapid river in England.
One of the greatest known tides is that of the Bristol channel, which
sometimes flows upward of forty feet. At the mouth of the river Indus,
the water rises thirty feet. The tides also are remarkably high on the
coasts of Malay, in the straits of Sunda, in the Red sea, at the mouth
of the river St. Lawrence, along the coasts of China and Japan, at
Panama, and in the gulf of Bengal. The most remarkable tides, however,
are those at Batsha, in the kingdom of Tonquin, in twenty degrees, fifty
minutes, north latitude. In that port, the sea ebbs and flows once only
in twenty-four hours, while in all other places there are two tides
within that space. What is still more extraordinary, twice in each
month, when the moon is near the equinoctial, there is not any tide, the
water being for some time quite stagnant. These, with other anomalies of
the tides there, Sir Isaac Newton, with peculiar sagacity, ascertained
to arise from the concurrence of two tides, one from the South sea, and
the other from the Indian ocean. Of each of these two tides there come
successively two every day; two at one time greater, and two at another
which are less. The time between the arrival of the two greater was
considered by him as high tide; that between the two less, as ebb. In
short, with these simple facts in his possession, that great
mathematician solved every appearance, and so established his theory as
to silence every opposer.
Besides the common and periodical tides, a variety of local currents are
met with in different seas, on different parts of the ocean, and for the
greater part at an inconsiderable distance from land. They have been
usually ascribed to particular winds; but their origin is not easy to
trace, as they have been occasionally found beneath the surface of the
water, running in a contrary direction to the stratum above, and can
not, therefore, have been owing to winds or monsoons. These particular
currents have been ascribed to the immense masses of polar ice, which
produce a greater degree of cold in the under than in the upper stratum
of waters; and it has been suspected that there is an under-current of
cold water flowing perpetually from the poles toward the equator, even
where the water above flows toward the poles. The great disparity of
temperature which is frequently found in deep and superficial soundings
of the same space of water, is thus accounted for.
The most extraordinary current of this kind, is that of the gulf of
Florida, usually called the Gulf stream, which sets along the coast of
North America to the northward and eastward, and flows with an
uninterrupted rapidity. It is ascribed to the trade-winds, which,
blowing from the eastern quarter into the great Mexican gulf, cause
there an accumulation above the common level of the sea. The water,
therefore, constantly runs out by the channel where it finds least
resistance, that is, through the gulf of Florida, with such force as to
continue a distinct stream to a very great distance. A proof of its
having thus originated is, that the water in the Gulf stream has been
found to have retained a great portion of the heat it had acquired in
the torrid zone.
A very singular upper current often prevails to the westward of Scilly,
and is highly dangerous to ships which approach the British channel.
Currents of this description are, however more frequently met with about
the straits of Gibraltar, and near the West India islands, the coasts of
which are so subject to counter-tides, or extraordinary currents, that
it is often dangerous for boats to land. They proceed to the westward,
along the coasts of Yucatan and Mexico, and running round into the gulf,
return into the great ocean by the straits of Bahama, along the coasts
of Florida, in order to pursue, in the north, the course ordained them
by the great Author of nature. In this course the waters run with an
extraordinary rapidity, passing on, however, by a motion so even and
imperceptible, that their speed is not realized by the spectator. But
against the shores and coasts of the various islands in their way, their
progress becomes very manifest, and even dangerous, interrupting the
navigation, and rendering it hardly possible to stem them in their
course.
In addition to these regular currents, there are others, called
counter-tides, which are observable on the sea-coasts and shores. In
places where these flow, the sea rolls and dashes in an extraordinary
manner, becoming furious without any apparent cause, and without being
moved by any wind. The waves rise and open very high, breaking on the
shore with such violence, that it is impossible for vessels to land.
These counter-tides have been, by some, ascribed to the pressure of the
heavy black wind-clouds which are occasionally seen to hang over an
island, or over the sea where they occur, though it is far more probable
that in every case they are caused by under-currents and hidden shoals,
by which the ordinary currents are checked and broken so as to cause the
effects described.
Somewhat similar to these, at least in its hidden cause, is the
celebrated Maelstrom on the coast of Norway, a view of which is given in
the cut. This is caused by the tides, in their violent passage between
the Loffoden islands; and its terrors, though at all times great, are
sometimes greatly increased by the winds. The roar of the sea, when the
Maelstrom is in full action, is said to be terrific. It is stated that
not only ships, but even whales, have been sucked into this vortex, and
killed by being dashed against the hidden rocks. The following
description, though imaginary, gives a correct idea of the destruction
of a ship in this whirlpool.
[Illustration: THE MAELSTROM.]
“The breeze, which had been long flagging, now lulled into a calm, and
soon a low continual hum, like that of an army of bees, which seemed to
rise out of the stilled ocean, became audible to every ear. Not a word
was spoken; every one held his breath whilst he listened with an
intensity of eagerness that betokened the awe that was fast filling the
heart. ‘It is the Moskoestrom!’ cried the boatswain. ‘The Moskoestrom!’
echoed the crew. ‘Away, men!’ shouted the mate; ‘down to the hold, bring
up the spare sails, clear the deck, set up a spar for a mast; away,
away!’
“The din of preparation drowned the stern hum of the distant whirlpool:
there was, however, an anxious pause when the new sail was set into the
air; and experienced sailors suffered themselves to be cheated with the
hope that there was still breeze enough to make the good ship answer her
helm. But, alas! the heavy canvas refused to expand its folds, and not a
breath of wind ruffled the dull surface of the sullen waters. They had
not another hope; the sailors looked on one another with blank dismay,
and now they heard, with awful distinctness, the roar of the terrible
Maelstrom, and the frowning rocks of Loffoden were but too plainly
visible on the right. It became evident to all, that the ship, borne
along by the tide, was fast drawing near the dreadful whirlpool. The
vessel continued slowly to approach, and the certainty of unavoidable
death became every moment more overpowering and intense. At first the
sailors stood together in a group, gazing gloomily upon one another; but
as the roar of the whirlpool became louder and louder, and the
conviction of inevitable destruction became stronger, they all dispersed
to various parts of the ship. * * *
“It was a beautiful day; the sun shone forth without a cloud to dim his
luster, the waves sparkled beneath his influence, and the white plumage
of a thousand busy sea-birds became more dazzling with his rays. The
isle of Moskoe was close at hand, and looked cheerful and inviting, but
the ship was not to approach nearer to its shores; the stream which bore
her along never suffered any vessel to pause in its career. And now
there arose at some distance ahead of the vessel, a horrible and dismal
bellowing. It was the voice of the leviathan in his agony; and when
those on deck who had still ears for exterior sounds looked forward to
ascertain its cause, they beheld a huge black monster upon the surface
of the sea, struggling against the irresistible stream, and with his
immense tail lashing the waters into foam, as he vainly strove to escape
from destruction. They beheld him borne away by the might of his furious
enemy; and they heard his last roar above the noise of the whirlpool, as
he was sucked down into the never satisfied abyss, and disappeared from
their eyes to be torn to atoms; for such is the fate of everything that
seeks the depths of the Maelstrom.
“The ship glides along faster and faster; she begins to toss and roll
uneasily in the angry rapids that boil around her; her race is nearly
run. Terrible! terrible moment! The ship hurries on to her doom with mad
impetuosity. She is in the rapids! she hurries along swift as a flash of
fire. She is in the whirl of water! round, round, round she goes; her
inmates catch hold of her bulwarks and of each other, to steady
themselves. And now her bow sprit is under the waves, and a wild shriek
of despair rises into the sky! The whirlpool, with greedy jaws, has
sucked her under.”
The water of the whirlpool is said to be two hundred and fifty feet
deep, and at ebb its noise is as loud as a cataract. In 1645, it was so
violently agitated by a storm, that in Moskoe the houses were so shaken
as to cause the stones to fall to the ground. Fragments of vessels
wrecked in the Maelstrom are frequently seen on the coast, brought up by
the return of the tide, their edges mashed and jagged as with a saw,
which would induce the belief that the bottom is composed of sharp
rocks.
Similar in its cause to the Maelstrom, though on a much inferior scale,
is the current, or whirlpool, called _Hurlgate_ or _Hellgate_, between
the East river and Long Island sound, near New York. In the narrow
channel here, the tide flows backward and forward with great force; and
there being large, irregular rocks in this channel, the water is thrown
into the most violent agitation. In passing through the place, it is
easy to see the waves seeming to boil as if in a pot. This place is
dangerous to vessels, and many have been wrecked here; though the
navigation is now so well understood, that fewer accidents happen than
formerly. The steamboats generally pass in safety, but still the superb
Oregon got upon the rocks here, within a few years, and came near being
lost.
Between Sicily and the main land are the straits of Messina, where the
current is rapid. Ancient mariners deemed this a terrible place; one
side they called Scylla, and the other Charybdis. The poets depicted the
sailor in this rapid, as beset by horrors; for if he escaped Scylla on
one side, Charybdis was ready to dash him in pieces on the other. This
idea has come down to our day, and has even passed into a proverb.
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