The daily crescent. [volume] ([New Orleans, La.]) 1848-1851, 1851-07-19
Height, Force and Velocity of Waves.


Few who have not "g gone down upon the sea in
ships" or witnessed the fury of storm on a rock
bound coast, can realize the magnitude and mower
oil the waves of the ocean. BY a stretch of the
imagination, nautical writer's some time, speak of
the waves as running mountains high," but exag-
gerated as Is the statement, il is doubtful whether
those who take it in literal sense do not really
entertain more just idea of the actual power Of
the waves than those who more ph losophcallv
measure their height by feet and inches, and form
corresponding idea Of their force
We have recently had melancholy instance of
the orce o the waves in the destruction of struc
ture which some of our best engineers considered
impregnable to the assaults of the elements This
event has given interest to the investigations
which have been made to the height and force
OF ,he waves, we hnd upon comparing various
authorities, that there is difference of opinion in
relation to these subjects. 1t was the commonly
received opinion among scientific men several
years since, that no wave rises over ten feet above
the ordinary level of the water, which, with a simi
lar depression, would give height of twenty feet
from she bottom OF the hollow to the crest Of the
wave. Humboldt, in his Cosmos, estimates the
height oil the waves at twenty-five feet.
IL IS not until quite recently, however, that any
careiui investigation OF the phenomena of waves
has been instituted. DR.. Scoresby, in paper read
before the British Association at Edinlurg, has
thrown much light upon this interesting inquiry
HIS researches were conducted during two Allan
TIC voyages In steamship under circumstances
very favorable tor observation. By an examination
instituted during hard gale, he found that the
average height of the waves was full fifteen feet
and upwards, and the mean highest waves about
iorty.three feet above the level OF the hollow. He
also found that after storm of about thirty. six
hours duration, which had abated several hours
before the observation, SO that the waves had per
ceptbly subsided, waves were noticed of twenty
SIX ieet average elevation from ridge to hollow and
even OF thirty feet They were, however, of no
great extent on the ridge.
When waves meet with an obstruction, their
ne'ght Is Increased. At recent meeting of the
British Association, Thomas Stevenson E.q., civil
engineer, gave the results of some careful observa-
TONS made at the Bell Rock Lighthouse, from
winch II appears that on the goth November. I847.
IN heavy ground swell, afer a storm, solid water
rose at the Bell Rock Lighthouse one hundred and
SIX feet above the level of the sea. If We recoect
Iign'' tne waves have been known to dash up the
sides OF the Eddystone Light, 10 the height of the
lantern, which is over one hundred feet above the
rock We are informed by Mr.. Bennett, the keeper
OF the lighthouse late on Minol's Rock. that he
mas known the waves to rise at that structure
move 'he Couplings of the piles, which were
lnlf'y hVe ieet above the rock, and about twenty.
five above the high water mark Here. however
Inc piles OF the lighthouse offered but small re.
sistance to the waves, compared with a solid
structure, and the only thing which would be likely
10 rale the water above the usual level, is its
striking against the rock ITSELF This, however.
pelng several feet below the level of high water.
would tend rather to break the waves than 10 in.
crease their height. There is good reason to be.
lieVe mat during the recen, storm which destroyed
the Lighthouse, the waves struck the store. .roo,r
the bottom Of which was fory.seyen feet above
the rock, and allowing five feet extra for the extra
water mark. as"
The length and velocity of waves varv. Tn
iounuing lhe cape OF Good Hope, waves, rather
swell are met with, vast, that a few ridges
an ana few depressons occupy the extent of mile.
inese waves propagate their motion at the rate of
thirty or forty miles per hour Mr. A. G. Findlev,
IN IN paper read before the Society of Arts, stated
shat waves OF from three hundred to four hundred
eee IN length, from crest to crest travel with ve
iocity OF twenty to twenty ty-seven and one.half
res per hour, whether they are five or ifty -four
feet IN total height They travel for great distances
and are often raised by distant hurricanes, having
been felt at st. Helena and Ascension, which are
hundred miles apart; and he remarked, that
~. probable that ground swells often originate at
sthe Zap OF Good Hope, distance of three thou.
SAND miles. Or. Scoresby, to whose investie alton
we nave already alluded, carefully estimated the
Veiocy @ the waves, and found it to be at the rate
ol oSo1 English statute miles per hour. He esti-
mated oo9 feet as the probable mean distance of
the waves, or the width passed over between cres.
ana crest. 1t is common error to suppose that
the water advances with the wave. II is The form
only winch advances, the water rising and falling
IN the same place, except when it reaches beach
e" ~ oe0oiiics really prog gTesSlve from the fact
mat 1t cannot sink directly down, and therefore
tails over forward.
These statements in relation to the height and
velocity OF waves, have perhaps prepared our
readers to estimate with degree Of correctness
their force. When we see column of water. at
least thirty feet in height, advancing with the
speed OF railroad tran we can readily imagine
that Its force is almost irresistible. We have al
ready mentioned the investigations of Mr.. Steven.
son; HIS observations on the force of the waves,
made by him with reference to the construction Of
marine works, are of much interest and importance,
These observations were made by means of the
marine dynometer. He found that during west
ery gale on the Goth March, 1s45, force of three
TONS per square foot was exerted, at the Skerrv-
vore lighthouse, in the Atlantic ocean. In he
herman ocean, at the Bell Rock lighthouse, the
greatest result registered was 3013 pounds. or
about one and half tons per square foot These
results are astonishing, and it is no wonder that in
the encounter with such force, the largest ships
are but toys. and wood and iron almost as fragile
as glass. Nothing but stone can be expected to
resist such force and that must be as firmly fas.
tened as the lodges on which the waves spend
their fury. 'r'AN
HoU Cattle XIII Trees,-It is noticeable fact
that tree ever SO thrifty and of whatever kind, to
t IL