Weekly national intelligencer. [volume] (Washington [D.C.]) 1841-1869, 1852-02-28
SMITHSONIAN LECTURES.

We make room in this paper for the following
synopsis of two of the series Of Lectures on Geo
logy now in course of delivery at the Smithsonian
Institute in this city by Professor SILLIDAN, with
which we have been favored by a competent hand:
The section of the strata beneath the city of Paris
which had been described in former lecture again
presented for the sake Of those persons peent that
not then in attendance The section 300
feet in depth with the fountain of water at the bottom
and the jet deau gushing out at the top of the tube
Remarks made upon the evidence Of progress in
the arrangement Of the globe which derive from fos
sls The earth is vast cemetery of departed beings,
and only very small portion Of them has been un-
covered
Instead therefore, of supposng that the evidence from
this has been exaggerated may be that
have fallen very far short receiving the full impress
sion which it may fairly produce; it will doubt con-
stanty increase in extent and value with the of
observation 6nd research. ~
The fresh water hydra described at the close of the
last lecture affords prelude the great family of
phytes called coras, inasmuch beth polypsthat
is the living animal is susceptible of division without
destruction and parts removed replaced by the
inherent powers of life possessed by these extraordinary
animals The coras frequent chiefly the tropical
the building coras cannot live in water colder than
$50 of Fahrenheit and they flourish best in that Of So n
80o Their auent region in the Pacific, between
28o of latitude on both sides Of the equator
Probably currents of cold water prevent their appear
the western coast Of South America and even
the Galapagos islands, situated under the equator
They abundant around of the East and West In
dia islands, especially the coast Of Florida and the
Bermudas although several degrees further north than
their limit in the Pacific rich in corals.
The reef building coras do work in very deep water
usually not deeper than 100 to $50 or 18O feet
nf hat
depths and in all lattudes but they comparatively
solitary and do congegae immense colonies build
ing up a vast world of their
The coral animals multiply like the hydra, by offsets
the parent animal The germ thus produced becomes
detached and floats about in the water until it attaches
itself fixed object and then it begins grow, and
becomes complex individual or colony.
1t is mistake to suppose that the little coral animals
live in and issue out of and return to the interior of the
cells that observed in their beautiful structures those
cells and the entire stony composed of lime
carbonate secreted* from the water by the little animals
and disposed of by them in consequence of vital power
to produce those beautiful structures which
and admire We say why they build in such FORMS
nor assign any why they should not build
in this The entire animal material pervades and
encoses the coral structure forming colony which may
be regarded unity collection of individuals
having Siamese connexion. injury is inflicted upon
any portion of living coral structure it is felt by the
whole family. If piece of living coral mass is broken
off, the whole colony recoils by of their deli
expanded MEMBERS showing that they nsen-
sible to pan but Immediately the work goes be-
fore and the amputaed mutiatcd parts replaced
by living members Thus there is perpetuy lung
as salt water temperature and food supplied
Nothing exceed the beauty Of the coral groves
beneath the clear the expanded pealke parts
of the living animals present nnumerabe feeding mouths,
surrounded by delicate movable parts coored green
red variousy marked, and thus, being ex-
tended SCALE they show all the beauty of flower garden
ssty the pictures painted by the poets when they
have described coral groves beneath the ocean wave
Among their branches also may be fishes Of the most
splendid colors swimming about in marine fary-and
Some fishes certain sharks for example, feed upon the
coral banks and may be browsing upon the living
coral swallowing of course the stony portion along with
the animal matter and the exuvia deposited from these
repasts forms nconsderabe portion of the cacareous
mud which subsidies and aids in filling up the interstces
among the corals thus tending produce firm and solid
rock. f
1t was recommended to the audience to visit the Pa
tent Office the splendid collection of corals dead
corals the animals live Of the salt water)
brought home by the great expedition among many
I interesting objects of natural history
The coral animals build sometimes upon the border Of
the shore of the islands the structure forms shelving
beach and is called fringing coral
The barrier reef constructed distance from the
shore it also rises from the sloping decvity but is
menced in deeper water although not below the normal
limit Of the reefbuding zoophytes The structure rises
gradually to the surface and surrounds the island
less completely produces natural breakwater
on the rim Of which the breakers form white line
of foam while the water within the barrier is calm
and undsturbed harbor is thus formed for the ships
which enter a certain natural openings which pre-
served by the streams Of fresh that down from
the mountains and pass into the and in these suces
the coras do not build they cannot live in fresh
brackish water The coral reefs Sometimes very
extensve along the coast Of New Holland reef extends
100 miles, and there many Others all Of great al
though inferior dimensions The coral agoons are very
the Of various diameers from mile forty fifty
miles. Often circular rim narrow strand forms a
perfect harbor whose entrance lies usually leewar
Into these natural havens the ships and ride in
curity while the pillows break against the
barrier built up in the by the humble animals
whose masonry surpasses in rmness the strongest ar
fetal breakwaters built by the hand of man for granite
and marble in these structures often yield to the violence
Of the winds and while the coral walls remain.
Beautiful and drawings and pictures illustrated
this subject and theory Of Mr. Darwin supported also
by Mr. Dana stated to account for the agoons
but would be hardly ineligible without the drawing by
which it illustrated.