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96
THE OCEAN.
fluids, and know how to apply to all their phenomena of acceleration,
retardation, increase, interference, and equilibrium the most complicated
and most minute formula? of high mathematics. It would also be indispensable to know every fact respecting the form of the shore, and the
inequalities of the bed of the sea.
Reduced to its principal elements, the theory of tides set forth by
Laplace, and generally adopted since, is very simple. The earth is not
an isolated body in space; it is attracted by all the nearer heavenly
bodies, and it is, indeed, in great part this force of gravitation which
causes it to turn round the sun, and retains the moon as its satellite. Let
us imagine for an instant the earth to be covered with water over all its
surface, and subject to the attraction of the moon alone. This superficial
part of the planet would be more strongly attracted than the solid portion, since it is nearer to the moon which attracts it; and owing to the
facility with which liquid particles glide one over the other, it would
swell, so to say, toward the moon till its weight would be in equilibrium
with the attracting force. It would then form an intumescence, the summit of which would be exactly on the ideal line which unites the centre
of the earth to that of the moon. On the other side of the planet, accorcfc
ing to the general theory, the waters ought to swell in a corresponding
wave, and that from a precisely contrary cause. The liquid strata on this
part of the earth being farther from the moon than the solid kernel, are
less attracted than it, and in consequence must remain slightly behind,
1 . . -. * ' • .^cggS
iBni
i-V. ,, f- '■'■'. )■ fi
HEBh ^amw^wWrn
'
■r\ ^g
"^^^fes; ': '■' ' '"
Hvr ■-- wax
• ":>^HMk,'■■■""'''<■*
^)
'■'■-., ■'-■;.;.
;.' ;''"v||, ^
-/■' '
fff 11"
■Attraction
j. ?j$3?~ ■ *'r;fM
: '-':■'.
~~t -'
. of the MOON . .
SlllSfiSv;?;;:'
mttmmm?'-r :-.JsaM
f:-.'J':~~'
Fig. 26.*—Lunar Tide.
thus forming a new intumescence, the summit of which will be found on
a prolongation of the line uniting the planet with its satellite. Considered
as a whole, the mass of marine waters would thus assume the form of an
ellipsoid, having its greater axis directed toward the moon, which is the
* This illustration, as well as Figs. 27 and 29, have been borrowed from the fine work by
M. Amedee Guillemin, entitled Le Ciel.
| Title | The ocean, atmosphere, and life |
| Creator | Reclus, Elisée |
| Publisher | Harper |
| Place of Publication | New York |
| Date | 1873 |
| Language | eng |
| Type | Books/Pamphlets |
| Title | 00000109 |
| Type | Books/Pamphlets |
| Transcript | 96 THE OCEAN. fluids, and know how to apply to all their phenomena of acceleration, retardation, increase, interference, and equilibrium the most complicated and most minute formula? of high mathematics. It would also be indispensable to know every fact respecting the form of the shore, and the inequalities of the bed of the sea. Reduced to its principal elements, the theory of tides set forth by Laplace, and generally adopted since, is very simple. The earth is not an isolated body in space; it is attracted by all the nearer heavenly bodies, and it is, indeed, in great part this force of gravitation which causes it to turn round the sun, and retains the moon as its satellite. Let us imagine for an instant the earth to be covered with water over all its surface, and subject to the attraction of the moon alone. This superficial part of the planet would be more strongly attracted than the solid portion, since it is nearer to the moon which attracts it; and owing to the facility with which liquid particles glide one over the other, it would swell, so to say, toward the moon till its weight would be in equilibrium with the attracting force. It would then form an intumescence, the summit of which would be exactly on the ideal line which unites the centre of the earth to that of the moon. On the other side of the planet, accorcfc ing to the general theory, the waters ought to swell in a corresponding wave, and that from a precisely contrary cause. The liquid strata on this part of the earth being farther from the moon than the solid kernel, are less attracted than it, and in consequence must remain slightly behind, 1 . . -. * ' • .^cggS iBni i-V. ,, f- '■'■'. )■ fi HEBh ^amw^wWrn ' ■r\ ^g "^^^fes; ': '■' ' '" Hvr ■-- wax • ":>^HMk,'■■■""'''<■* ^) '■'■-., ■'-■;.;. ;.' ;''"v||, ^ -/■' ' fff 11" ■Attraction j. ?j$3?~ ■ *'r;fM : '-':■'. ~~t -' . of the MOON . . SlllSfiSv;?;;:' mttmmm?'-r :-.JsaM f:-.'J':~~' Fig. 26.*—Lunar Tide. thus forming a new intumescence, the summit of which will be found on a prolongation of the line uniting the planet with its satellite. Considered as a whole, the mass of marine waters would thus assume the form of an ellipsoid, having its greater axis directed toward the moon, which is the * This illustration, as well as Figs. 27 and 29, have been borrowed from the fine work by M. Amedee Guillemin, entitled Le Ciel. |
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