of the calcareous shells of Foraminifera--some of them entire,
others broken up into minute particles--we interpret the phenomenon
by the fact that the dredgings obtained from certain parts of
the ocean-bottom, consist almost entirely of remains of existing
Foraminifera, in which entire shells--the animals of which may be yet
alive--are mingled with the debris of others that have been reduced by
the action of the waves to a fragmentary state.
"Now, in the fine white mud which is brought up from almost every part
of the sea-bottom of the Levant, where it forms a stratum that is
continually undergoing a slow but steady increase in thickness, the
microscopic researches of Professor Williamson have shown that not only
are there multitudes of minute remains of living organisms, both animal
and vegetable, but that it is entirely or almost wholly composed of
such remains."
[Illustration: ORGANISMS FROM MUD.]
The water of the sea is everywhere salt, except at the mouths of
great rivers, where the quantity of fresh water displaces that which
properly belongs to the sea. The cause of its saltness is the solution
of a natural mineral (chloride of sodium) which exists in the earth
in great abundance in layers of a crystalline structure, and as this
chloride of sodium (common salt) is soluble in water, of course it is
all dissolved by the water in whatever situation they may come into
contact with each other. The composition of sea-water differs slightly
in different parts of the earth, the southern seas being slightly
more salt than the northern. As a general rule, about five per cent.
of solid matter is contained in sea-water, of this rather more than
half (5.7) is chloride of sodium; the greater part of the other half
consists of different salts of magnesia, and this is the whole source
of the medicines known as Epsom salts and magnesia, the former being
the sulphate and the latter the carbonate of magnesia. Iodine, another
article used in medicine and photography, is also extracted from
sea-water, which however contains but a very minute portion, too small
to be detected as a general rule, but extracted by burning certain
sea-weeds, in the ashes of which it is found in sufficient quantity to
be separated.
Although the sea as a whole keeps its level, yet in various parts it is
constantly rising and sinking, sometimes at one place and sometimes at
another; these risings and fallings are called tides, and are caused
by the joint action of the sun and moon, that is, by their attraction,
acting at different distances. First it must be observed (as is well
known) attraction varies inversely as the square of the distance, that
is, if the moon were twice as far off, her attraction of the earth
would be one-fourth of what it now is, if three times as far off,
one-ninth, and so on.
The moon's average distance from the centre of the earth (A to C, in
the diagram) is about 240,000 miles, or about 60 times the earth's
radius (B C), which is a little under 4000 miles, consequently if the
distance from the moon to the centre of the earth (A C) be expressed
by 60, the distance to the nearest surface (A B) will be 59, and the
farthest surface (A D) 61. The moon will attract the point B with a
force of 1/59^2 or 1/3481, the point C with the force of 1/60^2 or
1/3600, and the point D with the force of 1/61^2 or 1/3721. Now as
the force at C is greater than at D, the earth itself will be pulled
away from the water at D, and leaving it a little behind, will produce
a high tide there, this tide is known as the "inferior tide" (2).
Again as the force at B is greater than at C, the water at B will be
pulled away from the earth and produce a still higher tide, called the
"superior tide" (1), or that which takes place when the moon is due
south. This heaping-up of the waters by the moon, to the height of
4-1/2 feet (on an average) causes corresponding depressions to the same
depth in those parts of the earth which are situated between the raised
parts, making a difference between high and low-water of nine feet due
to the moon; precisely the same effects are produced by the sun, but
though his attractive power is so much greater than the moon's, his
distance is also so much greater, that the heap of water he can raise
is somewhat less than 2 feet, and makes therefore less than 4 feet
difference between high and low-water, due to the sun. When the sun
and moon are both on the same side, or on opposite sides of the earth
(as at new or full moon), then the attraction of both act together and
produce "spring tides," with a difference of 13 feet; at first and last
quarter the sun and moon oppose each other, acting in cross directions,
and the difference is then only 5 feet. But these effects could only
take place in the wide open space of an ocean, and when other forces do
not interfere, such as obstruction to the tide-waves by land, &c.
[Illustration: DIAGRAM OF THE TIDES.]
Inland seas (as large as the Mediterranean even) have but very little
tide, while pinched-up rivers may have a great rush of tide, as at
Bristol, where it rises to 45 feet sometimes, and at Anapolis in Nova
Scotia, to so much as 120 feet! Wind will also accelerate or retard
both the speed and height of the tides. London receives a much greater
tide than its due, for the tidal-wave being interrupted by Ireland and
England, rolls up the western coast (taking a northerly direction) with
such force as to swing round the Shetlands and all down the eastern
coast of Great Britain. The direct Atlantic wave also, when split by
our island, rolls along the south coast from Land's-End to Dover,
rushes through the "Straits," and meets the backward wave which has
been travelling round by Scotland (as before mentioned), the two then
pour into the Thames and give an otherwise quiet river a high and
useful tide; so that London receives two tides, the southern one nearly
10 hours after Cornwall, and the roundabout one not till nearly 23
hours after it first reaches England.
[Illustration: RIVER THAMES.]
The waters are the great highway throughout the whole world, and what
an easy transit it has formed to those nations sufficiently civilised
to require a further knowledge of the world, and thence procure for
themselves luxuries not obtainable at home--at the same time, spreading
civilisation wherever they go!
If the oceans, instead of forming one great concourse of waters, had
existed in the form of inland seas or great lakes, the great chains
of mountains, deserts, and uninhabited tracts of earth, would, in
some cases, have formed impassable barriers, whilst in other parts
civilisation would have been impeded from the easy access of the more
savage tribes, who would have despoiled the more fortunate by inroads
amongst them, mingling with or exterminating them, and checking the
onward progress of civilisation. And this has always existed where
great tracts of land are, which are the last parts of the world to be
civilised, and in many parts remain as rude as they were thousands
of years ago. All this is owing to the good and wise arrangement of
water and land, and is an instance of the care and foreknowledge of
God, who has provided for the onward progress of that creature to whom
alone such a progress has been allotted; but as they now exist the
oceans form impenetrable barriers to the savage, so as to restrict
his brute force and uncultivated habits spreading, while they form
easily-traversed highways to the more civilised nations, enabling them
to spread their civilisation without contamination to themselves, but
to the advancement of others.
The oceans are now navigated by thousands of vessels engaged in
mercantile objects, and it is perfectly astonishing with what rapidity
and safety these great tracts of water are crossed.
In one of Chambers's "Papers for the People," called "Ocean Routes," is
the following, speaking of the perfecting of the steam-vessel:--
"The regularity, speed, and safety with which the voyages of these
vessels were made, soon pointed them out as the best conveyance both
for passengers and the mails.
"In 1821 they were employed on the latter service between Dublin and
Holyhead, and between Calais and Dover; and now, with few exceptions,
all the channel and ocean-work of the Post-Office is done by steamers,
and all the passengers and much of the goods' traffic between the parts
of Great Britain and Ireland, have been within the last quarter of a
century transferred to them.
"After the steamboat had thus passed through the various stages of
infancy and childhood--had tried its strength on English rivers, in
the Irish Sea, and in the British Channel--men began to ask, was it
not strong enough and old enough to do more? Could it not cross an
ocean as well as a channel--take letters and men, and merchandise to
America, India, and Australia, as well as to Ireland and France? In
this question were involved considerations of the highest importance to
all the world, but particularly to this country, for no other country
has such extensive foreign possessions as Great Britain, or carries on
such an extensive trade.
"With the exception of the United States, all the colonies planted by
the British remain parts of the empire, while Spain and Portugal have
lost nearly all those rich territories, extending over the fairest
portion of the American continent, that at one time acknowledged the
sway of the houses of Bourbon and Braganza. The foreign possessions
of France are insignificant, and, of the other nations of Europe,
the Dutch alone possess a territory abroad greater than they have
at home.... The proud position of Britain among the nations, the
necessities of her foreign trade, and the wants of her colonies and
dependencies, apart from all other considerations, rendered it fitting
and natural that she should lead the way in maritime enterprise, and
teach the nations how to navigate the ocean by steam.
"Nor has she failed in this high task; for, within thirteen or fourteen
years, since the question was first proposed, she has established lines
of gigantic steam-vessels that are now traversing with regularity and
safety every ocean, steaming altogether more than a million and a
quarter miles every year, and distributing letters and newspapers all
over the world, at a cost to the country of about £650,000 per annum."
The rapidity and ease with which thousands of troops were lately
conveyed to the Crimea and India, together with all their stores,
horses, &c., form one of the most wonderful feats of ocean navigation
ever performed, and point out the beauty of those arrangements which
enable man to traverse the whole earth, whether by land or by water, so
that it may fairly be said that the civilisation of the world depended
and still depends upon the waters.
INTRODUCTION TO THE ORGANIC KINGDOMS OF NATURE.
The foregoing descriptions refer to the great works of God as seen in
those creations which possess not that most wonderful attribute--life.
There is no limit in extent, in quality, or in number, to these works;
their extension appears to be infinite; their magnitudes are large
or small, just as we compare them one with the other. This earth is
an enormous mass, contemplated in comparison with ourselves, but an
insignificant speck when compared with the sun, and there are certain
laws, chemical and mechanical, which govern them all--heat, light,
and electricity permeate all the infinity of space--attraction exists
everywhere. There are no individual existences among them; all are
made up of matter combined according to certain definite chemical
laws, and always obedient to them under the same conditions--moving
according to certain mechanical laws, and always obedient to them. The
Creator who made these lifeless masses made also the laws to regulate
them; but, besides these, it has pleased Him to form certain other
creatures not for an instant to be compared in size or quantity with
the former, and made up also of certain chemical compounds obedient
to the mechanical and chemical laws, with one more addition, that
unknown, inexplicable attribute--life. This wonderful quality exists
in all organic beings; they obtain by it individual identity; they are
whole creatures--imperfect with any part taken away, also imperfect
with any addition. Clay is clay, in any quality or form; iron is
iron, whether a grain or a ton; but a tree is only a tree when it
is complete. We cannot say "some tree," as we would "some clay," it
must be _a tree_, or several trees, each a separate and complete
existence--perfect in itself--made up of solids and fluids, and
possessing certain attributes, namely, a constant circulation of its
fluid parts, a constant appropriation of food and rejection of waste
matters--growth thereby to a certain definite form, and in many a
definite size, together with the production of germs, capable, under
certain conditions, of producing beings exactly similar to themselves.
This constitutes organic life, and is possessed by all vegetables.
Animal life is exactly the same, with the super-addition of will or
mind in its most perfect state, of instinct or some analogous function
in its lower states, or in quite the lowest--a chemical and mechanical
difference only, such as shall determine the choice of food and mode of
assimilating it. This difference consists in the vegetable feeding upon
inorganic food, and the animal on food which has received the stamp of
organisation. Creatures possessing life, whether vegetable or animal,
are called organisms. It is found that these organisms are made up of
certain atoms united in larger multiples than in inorganic substances,
which are either simple or compounded of but few atoms; thus water is
composed (every atom of it) of _one_ atom oxygen, united to _two_ of
hydrogen. Common salt (every atom of it) is composed of _one_ atom of
the metal sodium with _one_ atom of chlorine. Chalk is compounded of
_one_ atom of calcium in union with _one_ of oxygen, and this united to
one atom of carbonic acid, itself composed of one atom of carbon with
_two_ of oxygen. But organic compounds are often made up of four or
six elements, united in multiples of their usual combining quantities.
Thus, grape-sugar is made up (every atom of it) of 24 atoms of carbon,
28 of hydrogen and 28 of oxygen; these 78 atoms unite and form one
compound atom, of which the sugar is wholly compounded, and thus,
from such a complex nature, it happens that most organic compounds
are decomposed by even a moderate degree of heat--all by a heat equal
to red-hot iron. From these facts, it may be therefore stated, that
all organisms are complete in themselves, have definite lives or
existences, appropriate certain matters to themselves, grow thereby,
and are compounded of organic atoms.
THE VEGETABLE KINGDOM.
[Illustration]
QUANTITY, DISTRIBUTION, AND OFFICES OF THE VEGETABLE.
In contemplating nature there are few things which give more delight
than the beauty and variety of the vegetation which clothes the surface
of the earth, whether it be that we contemplate the grassy covering
of the plains of the Old World, or the immense "prairies" of the New,
spreading out as it were into seas of grass, and giving food and
shelter to thousands of wild animals; or gaze upon the rocky height of
some vast mountain range, and see the gigantic oak or pine, forming
by their wide-spread shades the solemn forest which extends for miles
beneath us, and which forms a shelter for the various tribes of birds,
monkeys, and other animals, to whom it is a home of happiness and
plenty--under every aspect the contemplation of nature's clothing fills
the mind with awe and admiration.
There is hardly anything more refreshing to the mind than the
contemplation of trees and shrubs congregated into a wood, the floor
of which is carpeted with mosses and flowers, where the gigantic and
gnarled trunks of the forest trees covered with many-coloured lichens
starting up all round, circumscribe the view, while the wide-spreading
boughs and the leafy canopy overhead exclude the sun's rays. It is here
that one views nature in her purest forms and colours, untouched by the
destroying hand of artificial arrangement.
The immense preponderance of the vegetable over the animal world in
quantity compensates somewhat for the superior organisation and the
intelligence of the latter, which must be studied in the individual,
while the vegetable world, which can be contemplated in the mass,
almost overwhelms the imagination with its vastness. It is indeed
impossible to compute the amount of vegetation in the great forests
of America and Russia (in which latter country are the largest in the
world), covering hundreds, nay thousands, of square miles with one
continuous growth of timber. That forest in Russia through which the
river Pechora flows, extends over a space of 150,000 square miles!
The whole mass of animated existence sinks into insignificance when
compared in quantity with this; and when to these forest-tracts are
added the thousands of square miles of grass and heaths which grow in
some climates with wonderful luxuriance, the amount of the vegetable
kingdom is at once placed beyond all comparison with the animal kingdom
in point of quantity. Cooper, in his American novels, describes the
prairies as great seas of grass extending as far as the eye can reach,
and rising to a height of 8 or 10 feet; and Humboldt describes some of
the grasses on the plains of the Oronoco, as being so gigantic that
they measure 18 feet from knot to knot, and says the Indians use them
for blow-pipes to shoot their poisoned arrows from. And--as though it
were not sufficient that the earth should bring forth everywhere all
kinds of trees, shrubs, and grasses--the waters of the ocean itself are
often filled with vegetable life; in some tracks the tangled sea-weed
(_Fucus Natans_) is so dense as to impede the onward progress of ships
for hundreds of miles together.
Humboldt, in his "Views of Nature," describing the two great banks
of sea-weed, says: "The two banks of sea-weed, together with the
transverse band uniting them, constitute the Sargasso Sea of the older
writers, and collectively occupy an area equal to six or seven times
that of Germany."
[Illustration: FIG. 1.--DIATOMA VULGARIS.]
[Illustration: FIG. 2.--VARIOUS DIATOMACEÆ.]
Nor is this the only vegetation which the great world of waters
contains, for if we descend from the contemplation of its larger
members we find them even surpassed in quantity by others of such
extreme smallness, that they can only be seen individually by means
of the microscope, but which exist in such prodigious quantities that
the mind can hardly realise the fact. These vegetable atoms have been
so increasing and depositing their minute coverings at the bottom
of most parts of the ocean, that for hundreds of miles their beds
are composed of nothing else, and it has been found that most of the
great changes on the surface of the earth have been effected by these
minute creatures and their companions of the animal world; for as we
find chalk-downs and coral-reefs formed by the remains of microscopic
animals, so productions of equal extent have been formed by the
smallest members of the vegetable kingdom, chiefly the "Diatomaceæ," a
race of minute vegetable productions which propagate by sub-division
and have the power of withdrawing earthy matters from the waters in
which they live, which forms a sort of shell or covering; this shell
at their death remains indestructible and gradually accumulates in
the bed of the sea (fig. 1). Examination of the various strata of the
earth shows that chains of hills, beds of marl, and almost every kind
of soil, whether superficial or raised from a depth, consist in a great
proportion of the earthy remains of these minute plants. These tracts
of land were once the beds of oceans which were thus gradually filled
up. The waters of the Antarctic Ocean are often opaque and quite brown
from the multiplicity of these creatures, the lead used on shipboard
for sounding coming up from the bottom covered with what appears to
be mud, but which on a microscopic examination proves to be nothing
else than the shells of these and allied species (fig. 2). Thus we
find the land and the waters are everywhere full of vegetable life;
the air itself moreover is so filled with the germs of vegetable and
animal creations, that it is quite impossible to exclude a portion so
small that it shall not contain any; in proof of which, any organic
substance set by for a few days in a vessel ever so carefully closed,
is shortly covered with a growth of mould consisting of fungi, which
under the microscope present most beautiful forms and colours (fig. 3).
The cause of this is a deposit from the air of the spores or germs of
these creatures, and the nature of the decomposing substance into which
they fall often determines the race or tribe which shall come to life
and inhabit it, showing plainly that but a few of these only among many
come to maturity, just as when a variety of seeds are thrown on any
particular kind of soil, only those to which the soil may be suitable
come to perfection.
[Illustration: FIG. 3.--_a_ _a_, MOULD FROM AN OLD BONE--_b_,
MOULD FROM JAM.]
Dr. Carpenter in his work on the microscope says:--"There are scarcely
any microscopic objects more beautiful than some of those forms of
mould or mildew which are so commonly found growing upon the surface
of jams and preserves, especially when they are viewed with a low
magnifying power and by reflected light; for they present themselves as
a forest of stems and branches of extremely varied and elegant forms,
loaded with fruit of singular delicacy of conformation, all glistening
brightly on a dark ground.
"The universality of the appearance of these simple forms of fungi
upon all spots favourable to their development, has given rise to the
belief that they are spontaneously produced by decaying substances,
but there is no occasion for this mode of accounting for it, since the
extraordinary means adopted by nature for the production and diffusion
of the germs of these plants adequately suffices to explain the facts
of the case.
"The number of sporules which any one fungus may develope is almost
incalculable; a single individual of the "puff-ball" tribe, has been
computed to send forth no fewer than ten millions. And their minuteness
is such that they are scattered through the air in the finest possible
dust, so that it is difficult to conceive of a place from which they
should be excluded."