The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1870-12-13
THE HARTH'4 CRUST.


The following is full synopsis of the lee
ture delivered before the Franklin Institute
on Thursday evening last, by Professor A.
r. Leeds, on ''The Making of the Earths
Crust
Whoever has visited the lovely Falls of
Trenton, in the State of New York, will have
noticed that the dark blue limestone, over
which the water pours at the bottom of the
glen, is filed with crustaceans and shells.
There are mutitudes of tie tiny rings of
crinodal stems, and sometimes the entire
fower-like body and branching arms
Of the lily encrinite many species,
too, of those curious crab-like animals
with great projecting eyes like horns, called
trilobites. Now if any one, who chauced to
be inclined to the study of nature, had passed
his childhood among rocks so filed with fos
sils, he would have turned conchologist. But
the school-boys who spend their holidays on
the Schuylkill or Wissahickon, the Delaware,
Drum creek, Darby creek, or the Brandywine,
and hammer away upon every rock they
meet, never encounter relic of fossil bird,
beast, fish, worm, or shell. They do, how
ever, find minerals in great abundance aud
in great variety. l made some while since
q catalogue of the minerals native to South
eastern Pennsylvania, and found that it in
cluded more than 100 well-defned species. If
10 these the varieties be added the number
does not fall far short of 200. There is no
large city in the country, New York, Boston,
Baltimore, Cincinnati, and Chicago all being
included, which possesses so rich a cabinet;
one, moreover, that is accessible to the stu
dent at all times and free of cost. AS con-
sequence, Philadelphia is and always has
been noted for its multitude of mineral col
lectors and fine mineral cabinets The col
lections of Mr.. Vaux, Mr.. Clay and Mr..
Trautwine are excelled by no private, aud
that of the irst-named gentleman by no pub
lie, museum in the country.
The youth who commences his geological
studies while rambling through the lovely
valleys and over the gently slopiug hillsides
that encircle our native city, commences his
geological studies as nature herself would
dictate were she to become articulate and
constitute herself his teacher. The layers of
rock which, piled one upon another, make
up the earth's surface, have been frequently
umes-the layers which are deepest
down and which, as we shall
presently see, were first formed, constituting
the Introductory books, and those lying near
the surface the concluding ones. If the stu
dent wishes, then, to understand geology, he
must read these books as nature has written
them, and begin with those which she wrote
first. Now one of the very earliest books is
in the possession Of the students who reside
in Philadelphia. OF the second, third, fifth
and many of the later books we possess but
fragments and must borrow them of our
friends who live in New York, New Jersey,
and along the Gulf, if we desire to read them
in full.
These books are written in what the stu
dent of general literature would be apt to
call the dead languages of natural history, its
Greek and Latin, so to speak. But there are
as many beautiful poems and strange stories
told in these dead languages by lips of stone
as Grecian poets sung, aud as equally worthy
of translation into speech Ineligible to those
who live at the present day.
The great fire at Alexandria that burned
the famous library destroyed, it is said, many
manuscripts which would have thrown light
upon the early history of the Asiatic mo-
marches. Similar catastrophes at the begin
ming of the worlds geological history de-
stroyed library as great as that which has
been left to us. So few are the surviving
fragments that all the sagacity of science is
required to rewrite that history, and when
rewritten ii is almost too marvellous to
admit of belief. 1t tells of time when the vital
and spiritual forces had not yet been set into
operation upon our planet. When from pole to
pole and from peel to core the earth was given
over to the fierce conflict of physical and ma
terial powers. When as yet the rocks were
fluid. Though ten years ago it would have
been rash assertion to make, yet in view Of
what the spectroseope has revealed to us con-
cerning the constitution of the solar atmo-
sphere, when some rocks were even gases.
When these rocks were part not of the earth
but of the air.
Strangely different then and now was the
earth's atmosphere. Then it was composed
of oxygen, hydrogen, nitrogen, sulphur,
chlorine, iodine, bromine, and the vapors of
certain easily vaporizable metals, such as
arsenic and tellurium. 1t stretched away
until it filed large part of the space in
cluded within the orbit of the moon. And if
the spectroscope reveals to us iron gas mag
nesium gas, and calcium gas as existing in
the solar photosphere, it is reasonable to sup
pose that these and many other similar
metals once existed upon our globe in the
gaseous form. Other substances, such as
gold, platinum, and the noble metals gener-
ally, silicon and carbon, the latter of which
can be converted into liquid only at the
most exalted temperatures, constituted the
fluid body of the earth.
At last that great day came when the par
ticles of oxygen and hydrogen had 80 far
decreased in temperature, that is to say,
commenced to move in such restricted
spheres, that it was possible for them to link
their divided existences into one. With that
act of union, water-water the physical life
blood of the world-came into being. Water
is to our earth what blood is to the life of
men, what sap is to the life of plants. 1t
has been said, and with truth, that man is
composed of handful of dust spread through
six pailfuls of water All vegetables aud
animals are composed of water, together
with some charcoal and nitrogen. A
great number of the mineral species now
known to exist are hydrateS that is consist
of from one tn forty part6 Watef alOno