Produced by Chris Curnow, Josephine Paolucci and the Online
Distributed Proofreading Team at http://www.pgdp.net. (This
file was produced from images generously made available
by The Internet Archive.)
Nature's Miracles
_Familiar Talks on Science_
BY
ELISHA GRAY, PH. D., LL. D.
VOL. I
World-Building and Life
EARTH, AIR, AND WATER
NEW YORK
FORDS, HOWARD, & HULBERT
COPYRIGHT, 1899,
BY
FORDS, HOWARD & HULBERT.
THE MERSHON COMPANY PRESS,
RAHWAY, N. J.
CONTENTS.
CHAPTER PAGE
INTRODUCTION, v
EARTH.
I. WORLD-BUILDING AND LIFE, 1
II. LIMESTONE, 12
III. COAL, 22
IV. SLATE AND SHALE, 31
V. SALT, 36
AIR.
VI. THE ATMOSPHERE, 42
VII. AIR TEMPERATURE, 51
VIII. CLOUD FORMATION, 60
IX. CLOUD FORMATION (_Continued_), 69
X. WIND--WHY IT BLOWS, 79
XI. WIND (_Continued_), 88
XII. LOCAL WINDS, 100
XIII. WEATHER PREDICTIONS, 110
XIV. HOW DEW IS FORMED, 115
XV. HAILSTONES AND SNOW, 124
XVI. METEORS, 129
XVII. THE SKY AND ITS COLOR, 134
XVIII. LIQUID AIR, 146
WATER.
XIX. RIVERS AND FLOODS, 152
XX. TIDES, 161
XXI. WHAT IS A SPONGE? 167
XXII. WATER AND ICE, 177
XXIII. STORED ENERGY IN WATER, 182
XXIV. WHY DOES ICE FLOAT? 192
XXV. GLACIERS, 198
XXVI. EVIDENCES AND THEORIES OF AN ICE AGE, 207
XXVII. GLACIAL AND PREGLACIAL LAKES AND RIVERS, 217
XXVIII. SOME EFFECTS OF THE GLACIAL PERIOD, 230
XXIX. DRAINAGE BEFORE THE ICE AGE, 239
INTRODUCTION.
Dear Reader: Please look through this "Introduction" before beginning
with the regular chapters. It is always well to know the object, aim,
and mode of treatment of a book before reading it, so as to be able to
look at it from the author's view-point.
First: A word about the title--"Nature's Miracles." Some may claim that
it is unscientific to speak of the operations of nature as "miracles."
But the point of the title lies in the paradox of finding so many
wonderful things--as wonderful as any miracle that was ever
recorded--subservient to the rule of law.
"But," you say, "a miracle does not come under any rule of law."
Ah! are you sure of that? It is true that we may not understand the law
that the so-called miracle comes under, but the Author of all natural
law does. We do not pretend to dispute but that the Power that made
nature's laws can change them if He sees fit; but we cannot believe that
He will ever see fit. It would destroy all order and harmony, all
advancement in science and knowledge of God's works, not to be able to
rely implicitly upon the laws of nature as consistent and continuous.
In putting out these little volumes, it is not to be understood that the
subjects treated will be more than touched upon, at the most salient
points. To do much more would require volumes of immense size, and life
would be too short for me to write or for you to read them.
Again: these volumes are "familiar talks." The Author wishes to sit down
with you--so to speak--and not hold you at arm's length.
It will be his aim to use the language of common life and to avoid all
technical names so far as possible, or, when they are necessary, to
explain their meaning. The object is to reach the thousands of readers
who have not and cannot have the advantages of a scientific education,
but who can by this means get at least a rudimentary idea of some of the
natural laws with which they are coming in contact every hour, and
through which the inner man has constant communication with the outer
world. It may be, too, that many young students will be helped by these
plain general views of topics which their text-books will give them in
detail.
A knowledge of the real things in the objective world about us and the
laws that govern them in their inter-relations is of practical value to
every man, whatever his calling may be. Not only will it be of value
practically, but it will also be a constant source of interest and
pleasure. Man is so constituted that he must have something to be
interested in, and if he has no resources within himself he looks
elsewhere, and often to his hurt, mentally, morally, or otherwise. If he
could have an interest awakened in him for the study and contemplation
of the natural world he would then have a book to read that is always
open, always fresh, always new. He is dealing with facts and not theory,
except as he uses theory for getting at facts.
A man who is all theory is like "a rudderless ship on a shoreless sea."
All he really knows is that he is afloat, and if he lands at all it is
likely to be in an insane asylum. The mind, in order to keep its
balance, must have the solid foundation of real things. Theories and
speculations may be indulged in with safety only so long as they are
based on facts that we can go back to at all times and know that we are
on solid ground.
It is the desire and aim of all good men to make their nation a truly
great people, with a civilization the highest possible. The character of
all kinds of growth is largely determined by the character of the
material upon which it feeds. The study of natural law can never be
harmful, but is always beneficial, for the student is then working in
harmony with law. It is the violation of law that makes all the trouble
in the world--whether physical, moral, or social. When we speak of
natural law we do not confine ourselves to what is commonly known as
chemistry and physics, and the laws that govern the material world, but
include as well the laws of our own being, as intellectual and spiritual
units. For all law, physical, intellectual, and spiritual, is in a sense
natural.
All departments of science are simply branches of one great science, and
all phases of human activity are touched by it. The preacher is a better
preacher, the doctor a better doctor, the lawyer a better lawyer, the
editor a better editor, the business man a better merchant, and the
mechanic a better workman, if they follow scientific methods. Indeed,
any man will be a better husband, father, and citizen, if he has some
trustworthy knowledge of the laws under which this great universe, down
to his own little part of it, lives, moves, and has its being.
NATURE'S MIRACLES.
EARTH.
CHAPTER I.
WORLD-BUILDING AND LIFE.
"In the beginning God created the heaven and the earth. And the earth
was without form, and void."
Whatever our speculations may be in regard to a "beginning," and when it
was, it is written in the rocks, that, like the animals and plants upon
its surface, the earth itself grew; that for countless ages, measured by
years that no man can number, the earth has been gradually assuming its
present form and composition, and that the processes of growth and decay
are active every hour.
The science that deals with the formations and stratifications that are
found on the earth and under the earth, and all the forces that have
been and are now active in their formation, is called Geology (earth
science). It is a science about which little is known by the average
individual, and yet it is one of transcendent interest, from the study
of which the lover of nature can obtain a vast amount of profit and
pleasure. When the uncultured man sees a stone in the road it tells him
no story other than the fact that he sees a stone and that it would
better be removed; and all the satisfaction he gets out of it is in the
thought that he has saved some unlucky wagon wheel from being wrenched
or broken. The scientist looking at the same stone perhaps will stop,
and with a hammer break it open, when the newly exposed faces of the
rock will have written upon them a history that is as real to him as the
printed page. He is carried back to a far-off time, where he sees the
processes and forces at work that have formed this stone and made it
what it is, not only in its outward form, but in its constitution, down
to its molecules and atoms. (The word "atom" is used in chemistry to
mean the smallest particle of an elementary substance that will combine
with the atoms of another substance to form new compounds of matter. And
molecules are made up of atoms.) The scientist looking at this stone
sees in it not only that mechanical and chemical agencies have
cooperated in the work of its formation, but that animal life itself may
have been the chief agency in bringing the materials together and giving
form to the peculiar architecture employed in its formation. If it is a
piece of limestone this latter statement will be eminently true.
Here is a powerful motive for the study of physical science. It is not
to be expected, nor is it possible, that every individual can be a
scientist in the strict sense of the word, but it is possible for
everyone of ordinary intelligence to become familiar with the salient
facts of science, if only a small portion of the time that is now
devoted to the reading of literature that is rather harmful than helpful
be spent in studying the phenomena and works of nature.
The acquirement of such knowledge would furnish every individual with a
constant source of instructive amusement that would never lose its
interest. He would not be dependent every hour upon people and things
outside of himself; because he would carry about with him inexhaustible
sources of instruction and pleasure that would furnish him continual and
helpful diversion and save him from a thousand morbid tendencies that
are always ready to seize upon an unemployed mind. There are many men
and women in the insane asylum to-day for the simple reason that they
have not made intelligent use of the mental powers that nature has
endowed them with.
Sermons are not always preached from pulpits. They are written in the
rocks and on the flowers of the field and the trees of the forest.
Let us then look a little at the underground foundation of all this
beautiful earth. And before attempting that, the question may arise in
some minds how we know what is so deep down under the surface.
Fortunately this is a question very easily answered. At some period
after the rocks were formed the crust of the earth was broken by
volcanic eruptions at various places and times, and turned up, as in the
formation of mountains, so that the edges of the various stratifications
of the rocks, from those near the surface down to the lowest rocks, are
exposed to view. Another means of knowing what the various formations
are has been by borings of deep wells. These borings, however, are only
confirmatory of what was well known before through the upheavals that
are plentiful in all parts of the world. There is abundant evidence that
all of the rocks and all of the strata of every name and nature (except
perhaps igneous rocks) were originally laid down in water. This is
evidenced not only by the stratifications themselves, but by the
evidences of sea-life everywhere present in the earth's crust. Before
the upheavals in the earth's crust began, the whole surface of the globe
was a great ocean of hot water. The substances of which the rocks were
formed were undoubtedly held in suspension in the air and in the water,
and by a gradual process were deposited in the bottom of the ocean in
layers, forming rocks of various kinds, according to the nature of the
substance deposited. Gradually the crust of the earth was built up until
it acquired a certain thickness; when, either from shrinkage under the
crust a great void was formed until it could not sustain its own weight,
or the pressure caused by confined gases and molten matter produced an
upheaval which broke the crust of the earth outward, causing great
wrinkles that we call mountain ranges. Undoubtedly both forces were
active in producing these results. When the gases and molten matter had
escaped through the rifts in the rocks caused by the upheaval there must
have been great voids formed that were filled up by the shrinkage of the
earth, causing much irregularity in its surface.
In some places there were enormous elevations, and in others
correspondingly deep depressions. The water that before was evenly
distributed over the surface of the globe, after the upheavals ran off
into the lower levels, filling up the great valleys, forming the seas,
and leaving about one-third of the land surface uncovered. It must not
be supposed, however, that the appearance of the land was caused by one
grand movement or upheaval, but that it has been going on in successive
stages through long ages of time. This is clearly evidenced by the rock
formations. The deposition of rock strata is still active in the bottoms
of the oceans, although not to the same degree as in former times. When
the upheaval took place the old stratifications were thrown out of
level, but the new ones that were then formed remained in a level
position until they were in their turn disturbed by some subsequent
upheaval.
The laws of gravitation would tend to precipitate the matter held in
suspension by the water straight down to the bottom, toward the center
of the earth, so that the plane of these stratifications would tend to
be parallel to the surface of the water, that is horizontal, until
disturbed. Then they would be tilted in many directions. Hence it will
be easily seen why the seams in the rocks, especially in and near
mountainous regions, do not lie in a horizontal position after an
upheaval, but are found standing at all angles, up to a perpendicular.
Viewed from this standpoint, the solid portion of the old world has gone
all to pieces. Wherever there is a chain of mountains it marks a
breakage in the earth's crust, and these mountains are not all on the
land, but extend under the seas so deeply that they are unable to lift
their heads above the surface of the water. The earth is no longer
round, except in general outline, but broken up into all sorts of
shapes that give the varied conditions of landscape that we find
whichever way we turn.
There are but few volcanoes that are active in this age, while in former
times they extended for thousands of miles. We still have occasional
earthquakes, but undoubtedly they are very slight as compared with those
that shook the earth millions of years ago.
If, now, we study the constitution of the earth's crust so far as it has
yet been penetrated, we find it divided up into periods called Primary,
Secondary, and Tertiary. The primary period reaches down to the line
where the lowest forms of animal fossils begin to be found. This is
called the "Paleozoic" period, which means the period of "ancient life."
From here let us first go downward. Immediately under this lies a
stratum of "Metamorphic" rocks. To metamorphose is to change; and
metamorphic rocks are those which have been changed by heat or pressure
from their original formation. This class of rocks lie on top of what
are called "Igneous" rocks, which means that they have been formed by or
subjected to heat. All lava-formed rocks are igneous. They are
unstratified,--not in layers or strata, but in a formless mass,--and in
this they differ from water-formed rocks.
If there is a molten center to the earth these igneous rocks are
undoubtedly the offspring of this great internal furnace. The
metamorphic rocks were primarily igneous and are changed somewhat in
their structure by the lapse of time. For instance, marble is a
metamorphic limestone. The difference between common limestone and
marble is in its molecular structure--the way in which its smallest
particles are put together. They are both carbonates of lime. But the
marble is made up of little crystals and will take a polish, while
ordinary uncrystallized limestone will not. The igneous rocks are
chiefly granite; and granite is formed of orthoclase-feldspar, mica, and
quartz. (The word "orthoclase" means straight fracture, and the
orthoclase-feldspar has two lines of cleavage at right angles to each
other.) This is the ordinary composition of granite, but there are a
great many variations, chiefly as to color and proportions of the
ingredients named.
The igneous rocks, then, are the lowest of all; then come the
metamorphic rocks; and as before stated, on top of metamorphic rock
begins the first evidence of life in its lowest form. The Paleozoic
(ancient life) or Primary period is made up of a number of subdivisions.
The first and oldest division is called the "Silurian" age, which is
underlaid by the metamorphic rocks and overlaid by the rocks of the
Devonian period. It is called Silurian, from the name of a kind of fish,
fossils of which are found in the rocks of this age, which are
distinguished for the absence of land-plant fossils and vertebrate
animals.
In the Silurian strata are found limestones, slate, flagstones, shales,
etc. On top of the Silurian begins the "Devonian" age, in which is found
the old red sandstone, as well as limestone and slate; and here begin to
be found the fossils of land-plants. On top of the Devonian lies the
"Carboniferous" series, which complete the series of the primary period.
In the lower part of this stratum is found carboniferous limestone,
which is overlaid by a kind of stone called millstone grit, and on top
of this lie the true carboniferous strata or coal-bearing measures. In
the coal strata are found the first reptile fossils.
On top of the coal measures begins the Secondary period, or "Mesozoic"
(middle life). This period is distinguished for the great development of
reptiles, and is called the "age of reptiles." In this age occur the
first traces of mammals, and birds, and fishes with bony skeletons.
Among plants we find here the first evidence of palms. The formation is
chiefly chalk, sandstones, clays, limestone, etc. We now come to the
last or "Tertiary" period, which brings us to the top earth. This is
chiefly formed of sedimentary rocks--those which have been formed by
the settling of sediment, in water.
While we are forced to these general conclusions in regard to the
building of the world, and to its subsequent distortion by the series of
upheavals that have occurred from time to time, and to the successive
"ages" of the layers of rock foundation of its crust, there are many
mysteries that remain unsolved and many questions will present
themselves to the mind of the reader. One of these questions is, Where
was the water and where was the earthy matter before its precipitation?
Matter, including water, can exist in the gaseous form, and we only need
to assume that there was a core of intense heat, to understand how all
the material that we find on the earth and in the earth could have been
held in suspension in the gaseous state until the cooling process had
reached a stage where the various combinations and recombinations could
take place in the great laboratory of nature. If we study the
constitution of the sun (and with the modern appliances we are able to
do so), we find that it is made up of some and perhaps all of the same
materials that are found here on earth. If there is no water existing,
in the sun, as water, there are the gases present which would produce it
if the conditions were right. And, for all we know, that flaming mass of
burning gases may some time go through the same kind of cooling and
building up in solids that our earth has experienced.
We thus have what may be called an outline sketch of the process of
World-building.