The center (the turbine) propeller, 16′ 6″ in diameter, cast of one
solid piece of manganese bronze, 22 tons in weight. The “Britannic”
like “Olympic,” is propelled by two sets of reciprocating engines, the
exhaust steam from these being reused in the low-pressure turbine,
effecting great economy in coal. The two “wing” propellers are 23′ 6″
in diameter and weigh 38 tons each.]
[Illustration: WHAT A SHIP’S TURBINE LOOKS LIKE
The turbine motor, 130 tons in weight (Parsons type). The steam plays
upon the blades with such power that they develop 16,000 horse-power
and revolve the propeller (turbine) 165 times a minute. The motor is 12
feet in diameter, 13′ 8″ long, the blades (numbering thousands) ranging
from 18 to 25¹⁄₂ inches in length.]
[Illustration: THE IMMENSE TURBINE MOTOR FULLY ENCASED--WEIGHT 420
TONS.]
[Illustration: HOW A FUNNEL APPEARS BEFORE IT IS IN PLACE
One of the four immense funnels--without the outer casing. Each is 125
feet above the hull of the ship and measures 24′ 6″ by 19′ 0″.]
[Illustration: WHAT A GREAT STEAMSHIP WOULD LOOK LIKE IF SPLIT END TO
END]
This view will give some idea of the interior arrangement of the
huge White Star Line triple-screw steamer “Britannic.” Many features
undreamed of a dozen years ago have been introduced in the passenger
quarters of this ship. As many decks are necessary to provide the
required space for state-rooms, public apartments, promenades, etc.,
several passenger elevators have been installed, which are a great
convenience for those who find the use of stairs irksome. There is
a fully equipped Gymnasium, a children’s Play Room for the younger
passengers, a Squash Racquet Court, a Swimming Pool with sea-water, and
the Turkish Bath establishment.
There are accommodations for over 2500 passengers as well as a crew of
950. The view shows how the ship is divided into numerous water-tight
compartments, so that should several of these sections become flooded
the rest of the ship would remain intact.
The lifeboats, of which there are sufficient to carry all on board, are
handled by a new device, by means of which the boats can be launched,
when filled, with greater ease and safety than hitherto. Each of the
great davits can handle several boats and they are long enough to carry
the boats clear of the side of the ship, should any accident cause her
to list to one side.
The “Britannic” is nearly 900 feet in length, and with her gross
tonnage of 50,000 is the largest British steamer in the world.
What Is Water Made Of?
Every kind of substance in the world is made up of tiny portions, each
of which is distinctly just what the whole mass is, but which are so
small you cannot see them. A pile of sand, or a cupful of sugar or salt
consists of a great many small grains. A cup of water too is made up of
what we would call small grains of water, or what we would call grains
of water if we could think of them in the same way as we do sugar or
salt or sand. These particles are so small that they could not be seen
separately, even if the particles did not have the ability to stick so
close together that we could not distinguish them even if they were
large enough to be seen.
The word used in describing these tiny particles in any substance,
water, sugar, sand, salt or anything else is molecule.
What Is a Molecule?
The word molecule means “smallest mass,” which indicates the very
smallest division that can be made of any substance without destroying
its identity. Every substance is made up of molecules, and in many
cases the molecules of one substance will mix with those of another
substance, while in other cases they will not. When you dissolve sugar
in water or melt lead or change water into steam, the physical body of
the substance is changed, but the molecules remain as they were. They
are only changed in so far as their relations to each other and to
those of another substance are concerned.
How Do We Know a Thing Is Solid, Liquid or Gas?
The relations of the molecules in any substance to each other is what
determines whether a substance is a solid, a liquid or a gas. A gas is
a substance in which the molecules are constantly moving rapidly about
among each other, but always in straight lines. A liquid substance is
one in which the molecules are also constantly moving about but which
do not move in straight lines. Solids are substances in which the
molecules stick together in one position by the power of cohesion which
they have. Cohesion means the power of sticking together.
How Big Is a Molecule?
We do not as yet know all there is to be learned about molecules. We
know through the wonders of chemistry that small as a molecule is, it
is still made up of smaller particles called atoms. An atom is the
smallest division of anything that can be imagined. We have found by
chemistry that even a molecule is capable of being divided, i.e., it
is made up of still smaller particles, but molecules are small enough.
An eminent scientist, Sir William Thomson, has given us probably the
nearest approach to a correct way of saying something of the size of a
molecule. “If a drop of water were magnified to the size of the earth,
the molecules would each occupy spaces greater than those filled by
small shot and smaller than those occupied by cricket balls.”
To get at what water is made of we must separate it through chemistry
into its parts or atoms. When we do this we find that a molecule of
water is made of three atoms or parts. Two of these are exactly alike
and consist of a gas called hydrogen, and the other part is another
gas called oxygen, concerning which gases we have already learned
much in the answers to other questions in this book. In other words,
when we separate water, which is a liquid, into its parts, we change
the relations of the molecules in the water which move in irregular
lines, into parts which move in straight lines and, when the molecules
of a substance, as we have already seen, move in straight lines, the
substance becomes a gas. On the other hand, when you freeze water, it
becomes a solid (ice), and in doing that you fix the molecules in the
water so that they stick to each other.
Men thought for a long time that water was an element like oxygen and
hydrogen, i. e., that its molecules could not be separated in its
parts and was, therefore, considered one of the things which could not
be divided up, but this was due to the fact that it requires a great
amount of power to break up the molecules of water.
What Is an Element?
An element is any substance whose molecules cannot be broken up and
made to form other substances. You can take one or more elements and
make a compound, which is what water is. A compound is a substance in
which the molecules are made up of at least two kinds of elements or
elementary substances.
~THE DIFFERENCE BETWEEN ELEMENTS AND COMPOUNDS~
The things we find in the world are known as either compounds or
elements. An element, as we have already learned, is something in
which the molecules cannot be broken up. A compound is, therefore, a
substance in which the molecules are made of molecules of one or more
elements and is either gas, liquid or solid, according to the relations
which these molecules have to each other. We have so far discovered
less than eighty real elements in the world, although since we find
a new one every little while, there are probably many more as yet
undiscovered.
Not all elements are gases, of course. Solids like copper, gold,
iron, lead and a number of others are elements. Among liquids we have
mercury, and of the gases we find hydrogen, nitrogen and oxygen,
which are the three wonderful gases about which we are about to learn
something, and these three are also the world’s most important gases.
Ammonia is an element, but, while we think of it as a liquid, the real
ammonia is really a gas. Our household ammonia is really a compound of
ammonia with something else.
What Is Hydrogen Gas?
Hydrogen is one of the elementary substances in the form of a gas. It
has no color or taste or odor, so we can neither see, smell nor taste
it. It is the lightest substance known to the world. We have by the aid
of chemistry been able to catch and retain it in sufficient quantities
to weigh it and have found it to be lighter than anything else in
the world. It is soluble in water and some other liquids, but only
slightly so. It refracts light very strongly and will absorb in a very
remarkable manner with some metals when they are heated. It burns with
a beautiful blue flame and very great heat. When burned it combines
with oxygen in the air and forms water. Hydrogen is not poisonous but,
if inhaled, it prevents the blood from securing oxygen, and so the
inhaling of hydrogen will cause death. Hydrogen is not found free in
the air except in small quantities like oxygen and nitrogen and is,
therefore, secured by separating compounds by known methods. It can be
secured by the action which diluted sulphuric acid has on zinc or iron,
by passing steam through a red-hot tube filled with iron trimmings, by
passing an electric current through water and in other ways. Hydrogen
is absolutely necessary to every form of animal or vegetable structure.
It is found in all acids.
What Is Oxygen?
Oxygen was discovered in 1774. It is an elementary substance in
the form of a gas which is found free in the air. It is colorless,
tasteless and odorless and, like hydrogen, cannot therefore be seen,
tasted or smelled. It is soluble in water and combines very readily
with most of the elements. In most cases when oxygen combines with
other things the process of combining is so rapid that light and
heat are produced--this combination is called combustion. Where the
process of combining with other substances acts slowly the heat and
light produced at one time are not enough to be noticed. Where metals
tarnish or rust or animal or vegetable substances decay, the same
thing chemically is taking place as when you light a fire and produce
light or heat--you are making the oxygen combine with the substance
in the material which is burning. When iron is rusting or vegetables
decaying, the action is so slow that no heat or light is produced, but
the result is the same if some outside force does not stop the action.
The fire will burn until everything burnable which it can reach is
burned out, and in the case of the piece of iron rusting, the action
will go on slowly until the whole piece of iron is destroyed--or burned
out. Like hydrogen, no vegetable or animal life can live without oxygen
continually given it. Oxygen will destroy life and will sustain it.
All of our body heat and muscular energy are produced by slow
combustion going on in all parts of the body, of oxygen carried in
the blood after it enters the lungs. In sunlight oxygen is exhaled by
growing plants.
Oxygen is the most widely distributed and abundant element in nature.
It amounts to about one-fifth of the volume of the air belt of the
earth; about ninety per cent of all the weight of water is oxygen. The
rocks of the earth contain about fifty per cent of oxygen and it is
found in most animal and vegetable products and in acids.
What Is Nitrogen?
Nitrogen is the third of the world’s wonderful and important gases.
It is also without color, taste or smell. It will not burn or help
other substances to burn and it will not combine easily with any other
element. It will unite at a very high degree of heat with magnesium,
silica, and other metals. About 7.7 per cent of the weight of the air
is nitrogen, so that it is a very important part of the air we breathe
and it is absolutely necessary in making all animal and vegetable
tissues. When united with hydrogen, it produces ammonia, and with
oxygen one of the most important acids--nitric acid. It is found free
in the air and is thus easily secured. Nitrogen, while very important
to all kinds of life, is known as the quiet gas. It stays quietly by
itself unless forced to combine under great power with other things,
and, even under those conditions, will combine rarely. We find a good
deal of nitrogen in the blood but, while we need the nitrogen which is
found in the blood, it does nothing particularly to the blood or the
rest of the body. The nitrogen which the body uses is valuable to the
body only when found in a compound. This nitrogen which the body needs
is secured through vegetable products such as the wheat from which our
bread is made, and which are said to secure their nitrogen through
the aid of microbes which are able to force the nitrogen of the air
into a compound. Some day perhaps we shall know all there is to know
about nitrogen, which is the least known of these three wonderful and
necessary gases.
Why Are Some Things Transparent and Others Not?
Transparency is produced by the way rays of light go through substances
or not. When light strikes a substance that is almost perfectly
transparent, it means that the rays of light go through it almost
exactly as they come in. We think quickly of glass when we think of
something readily transparent. Water is almost equally as transparent.
When the sunlight is shining on one side of a pane of ordinary window
glass, it causes every thing on that side of the window to reflect the
light which strikes it in all directions. When these rays of light
strike the window pane, they go right through and that is how we are
able to see the trees and grass and everything else through a clear
window pane. The same reason applies also to the water.
Some kinds of window glass (the frosted kind) we cannot see
through--they are not transparent. The surface of a frosted window pane
is so made that when the light rays strike it the rays are twisted and
broken, and do not come through as they entered the glass.
Sometimes the water is almost perfectly transparent. When water is
perfectly clear, it is quite transparent. When you look at or into
water that is not transparent, you will know that there are particles
of solid matter floating about in it which twist and mix the light
rays. If the water is not too deep you can see the bottom sometimes
even when there are some particles of solid substances floating about
in it, but the deeper the water the more of these solid particles there
are generally in it, so that it is impossible in most waters to see the
bottom if the water is deep. In some places, however, the water is so
free from floating particles that the bottom of the ocean can be seen
at quite considerable depths.
Why Is the Sea Water Salt?
All water that comes into the oceans by way of the rivers and other
streams contains salt. The amount is so very small for a given quantity
of water that it cannot be tasted. But all this river water is poured
into the oceans eventually at some point. After it reaches the oceans,
the water is evaporated by the action of the sun. When the sun picks up
the water in the form of moisture, it does not take up any of the solid
substances which the water contained as it came in from the rivers, and
while there is about as much water in the ocean all the time and about
as much also in the air in the form of moisture also, the ocean never
gets fuller; the solid substances from the river waters keep piling
up in the ocean and float about in the water there. The salt which is
in the river water has been left behind by the sun when it evaporated
the water in the ocean for so long that the amount of salt has become
very noticeable. The moisture which the sun takes into the air from
the ocean is eventually turned back to the earth again in the form of
rain. This process of evaporation and precipitation in the form of rain
is going on all the time. When the water which is in the form of rain
strikes the earth, it is pure water. It sinks into the ground and on
the way picks up some salt, finds its way into a river sooner or later,
and then evidently gets back into the ocean. All this time it has been
carrying the tiny bit of salt which it picked up in going through the
ground. But when it reaches the ocean again and is taken up by the
sun, it leaves its salt behind and so the salt from countless drops of
water is constantly being left in the ocean as it goes up into the air.
This has been going on for countless ages and the amount of salt has
been increasing in the ocean all the time, so that the sea is becoming
saltier and saltier.
Why Does Salt Make Me Thirsty?
The blood in our body contains about the same proportion of salt as the
water in the ocean normally. When the supply is normal we do not feel
that we have too much salt in our systems, but when you take salt into
your mouth the percentage of salt in the body is increased, and the
being thirsty, or the desire to drink water afterwards is caused by the
demand of the human system that the salt be diluted. The system calls
for water or something to drink in order that it may counteract the too
great percentage of salt in the system. Other things also, when taken
into the body in too great a proportion, cause us to become thirsty.
Thirst is merely nature’s demand for more water on account of the
necessity of reducing the percentage of some substance like salt, or
merely a necessity for having more water in the body.
What Are Diamonds Made Of?
We learned the definition of an element in our study of water and
other substances. Many things which were at one time thought by our
wisest men to be elements were later found to be compounds of other
substances. Water is one of these which we have learned is really not
an element at all, but compounded from two gaseous elements, hydrogen
and oxygen.
One of the most important elements in the world is the one out of
which diamonds are formed. Not because diamonds are so valuable, but
because the element referred to, carbon, is found in every tissue of
every living thing, both animal and mineral. This carbon is one of the
most useful of all elements, but is found in and used by living things
always in combination with some other substance. Carbon is combustible,
forming carbonic acid gas, from which the earth’s vegetation secures
its necessary carbon, which is very great in amount.
When heat is made to act in certain ways on the tissues of animal and
vegetable life we get charcoal, lampblack and coke. Carbon will combine
with more other substances than any of the other known elements. Its
wonders lie in the fact that under various treatments it produces
altogether different looking things, although remaining as pure carbon.
Our diamonds, for instance, are pure carbon, but our lead pencils,
that is, the part we write with, are also pure carbon, and the coal
we burn is carbon also. It would be hard to say which of these three
forms of pure carbon is most valuable to the world. A great many rich
people might say diamonds, while the poor people would surely say
coal, especially if you asked them in winter, while the people who
write books, and newspaper reporters, would probably say lead-pencils.
However, it would be better to choose diamonds, for if you have them
you can always trade them for coal or lead-pencils. A very small
diamond will buy quite a lot of either coal or lead-pencils. Carbon is
one of the solid elements which are not metals. A great many of the
important elements in the group of solids are metals.
What Causes Dimples?
A dimple is a dent or depression in the skin on a part of the body
where the flesh is soft. The fibers which lay in the tissue under the
outside skin help to hold the skin firm. These fibers which are, of
course, small run in all directions and are of different lengths. Now
and then these fibers will just happen to grow short in one spot or the
other and pull the skin in, forming a little depression, but producing
a very pleasing effect.
Why Does the Dark Cause Fear?
Fear is an instinct. We are by nature afraid of the things we do not
know all about. That is why knowledge is so valuable; when we know
about a thing we are sure of our ground. When we are where it is light
we can see what is there; when it is dark our imagination becomes
active and because we do not know for certain what is there in the dark
before us, we imagine things.
Fear of the dark, however, cannot be said to be entirely natural. It
comes naturally only when we have come to the age when we begin to
imagine things. Animals have no imaginative powers and they do not fear
the dark. Some people say that the fear of the dark is bred in us,
but little babies do not fear the dark. If they are properly trained
they will go to sleep in the dark and will prefer the dark. As they
grow older children begin to fear the dark, but that is because their
imagination is coming to life and because parents so often make the
mistake at this stage of training their children of either encouraging
the feeling of fear that darkness brings for the convenient means of
punishment it provides through threatening to put the light out, or
because they do not take the pains to show that there is no reason for
fear.
Most children who fear the darkness are really taught to do so
permanently by parents or servants. When a boy or girl first begins to
imagine things in the dark, many parents run quickly to the child and
say, “Don’t be afraid” or “There is nothing to be afraid of,” and in
doing this they perhaps mention the word “fear” for the first time.
Repetition of this will always cause the child to associate the word
“fear” with “darkness.” As a matter of fact when the boy or girl first
shows fear of the darkness, parents should go to them and quiet their
fears, but talk about anything else but fear and direct the child’s
mind away from any thought of fear.
[Illustration: ANCIENT EGYPTIAN ROPE.]