How Does an Elevator Go Up and Down?
Ordinarily, when we think of an elevator we think merely of the cage or
car in which we ride up or down. But the car is really only the part
which makes the elevator of service to man, and from the standpoint of
the machinery, is a relatively unimportant part of the equipment.
There are two principal types of elevators used to-day; the hydraulic,
which is worked by water under pressure, and the electric, which is
worked by electricity through an electric motor. The latter type,
because of the tendency towards the general use of electricity in
recent years, has largely superseded the hydraulic, and, as when you
think of elevators you probably have in mind those you have seen in
some huge skyscraper, we shall look at one of these.
What are the Principal Parts of an Elevator?
The most advanced type of elevator to-day is called a Gearless Traction
Elevator. In this elevator the principal parts are a motor, a grooved
wheel on the motor shaft called a driving sheave and a brake, all
mounted on one cast-iron bed-plate; a number of cables of equal length
which pass over the driving sheave and thence around another grooved
wheel called an idler sheave, located just below the driving sheave,
and to one end of which is attached the car or cage, and to the other
end a weight called a counterweight; also a controller which governs
the flow of electric current into the motor and thereby the speed,
starts and stops of the elevator car. Although the controller, motor,
brake and sheaves are usually placed way at the top of the building out
of our sight, they are really very important parts of the elevator.
The cage or car in which we ride is held in place by tracks built
upright in the elevator shaft, and the counterweight at one side of the
shaft travels up and down along two separate upright tracks. When the
car goes up the counterweight on the other end of the cables goes down
an equal distance. The counterweight is used to balance the load of the
car and to make it easier for the motor to move the car.
Electricity is the power that makes the car go up or down. The operator
in the car moves a master switch--in one direction if he wishes to go
up, in the other direction if he wishes to go down. This master switch
sets the electro-magnetic switches of the controller at the top of the
hatchway into action, electrically, and the controller in turn allows
the electric current to flow into the motor. The motor then begins
to revolve, gradually at first, and then faster, turning the driving
sheave with which it is directly connected. As this driving sheave
revolves, the cables passing over it are set in motion, and the car and
counterweight to which they are attached begin to move.
Why Does Not the Car Fall?
[Illustration: THE PRINCIPAL PARTS OF AN ELEVATOR]
Of course, the question of safety is a very important one in any
elevator, and you wonder what would happen if the cables broke. You
think of this especially when you are going up in one of the big
skyscrapers--where the elevators sometimes travel to a height of 700
feet. It can be truthfully said that on every modern elevator there
are safety devices which should make it practically impossible to have
a serious accident, due to the fall of the car. Every elevator is
equipped with wedging or clamping devices which automatically grip the
rails in case the car goes too fast either up or down. These gripping
devices can be adjusted to work at any speed that is desired above the
regular speed. It is not at all probable that all the cables will break
at once, because there are usually six of these, and any one of them is
strong enough to hold the car if the others break; but even if they all
should break the gripping devices on the rails will operate and hold
the car safely, just as soon as it starts down at great speed.
Suppose that the car should descend at full speed, but not sufficiently
fast to work the rail-gripping devices, it would be brought to a
gradual rest at the bottom of the hatchway, because of the oil-cushion
buffer against which it would strike. This is a remarkable invention,
with a plunger working in oil in such a way that a car striking it
at full speed will come to rest so gradually that there is scarcely
any shock. You have perhaps seen a clever juggler on the stage throw
an ordinary hen’s egg high into the air and catch it in a china dish
without cracking it He does it by putting the dish under the falling
egg just at the right moment, and bringing the dish down with the egg
at just the right speed, so that eventually he has the egg in the dish
without cracking it. The trick is in calculating the rate of speed of
the falling egg accurately and adjusting the insertion of the dish
under the falling egg to a nicety. The oil-cushion buffer in the modern
elevator works in very much the same way.
[Illustration: GENERAL ARRANGEMENT OF ROPING FOR GEARLESS TRACTION
ELEVATOR INSTALLATION.]
If it were not for the genius which has made possible these new types
of elevators we could not have the high buildings. The elevators in the
Woolworth Building are the latest type in modern elevator construction.
In this one building alone there are 29 elevators, and when you are
told that the electric elevators in the United States installed by
a single company represent a total of 525,000 horse-power, you will
have some idea of the power required to operate elevators all over the
country.
Does Air Weigh Anything?
Air is very light, so light that it seems to have no weight at all;
but, if you will think a minute you will see that it must have some
weight, because birds fly in it and balloons can be made to float
through it. It has been found that one hundred cubic inches of air
at the sea level weighs, under ordinary conditions, about thirty-one
grains. This seems a very small weight, but when we remember the
thickness of the atmospheric envelope over the earth we see that it
must press quite heavily upon the earth’s surface. There is a very
simple instrument called a barometer, which is used for measuring the
amount of this pressure. The name means pressure-measure.
Another striking feature of air is its elasticity, and this explains
something that is noticed by all mountain climbers. On a high mountain,
it is difficult to get enough air to the lungs, though one breathes
rapidly and deeply. The reason is, that the air at the foot of the
mountain is compressed by the weight of that above it, and consequently
the lungs can hold more of it than of the air on the mountain top,
which has less weight resting upon it and is, therefore, not so much
compressed. On account of the ease with which it is compressed, we find
that more than half of all the envelope of air that surrounds the earth
is within three miles of the surface.
When air is chemically analyzed it is found to consist of a number of
substances mingled together, but not chemically united. These include
nitrogen, oxygen, argon, carbonic acid gas, water vapor, ozone, nitric
acid, ammonia, and dust.
Oxygen is the most important of these constituents, for it is the part
that is necessary to support life. Yet, notwithstanding its importance,
it forms only about one-fifth of the entire bulk of the atmosphere.
Oxygen is a very interesting substance and many striking experiments
may be performed with it. If a lighted candle is thrust into a vessel
filled with oxygen, it burns very much more rapidly and brilliantly
than in air. A piece of wood with a mere spark on it bursts into flame
and burns brightly when thrust into oxygen, and some things that will
not burn at all in air, can be made to burn very rapidly in oxygen. For
example, if a piece of clock spring be dipped in melted sulphur and
then put into a jar of oxygen, after the sulphur has been set on fire,
the steel spring will take fire and burn fiercely. The heat produced is
so great that drops of molten steel form at the end of the spring, and
falling on the bottom of the jar, melt the surface of the glass where
they strike.
The other two substances found in pure air, nitrogen and argon, are
very much alike. They make up the remaining four-fifths of the air, and
are very different from oxygen in nearly every respect.
Nitrogen and argon resemble oxygen in being colorless, odorless, and
tasteless gases; and they are of nearly the same weight as oxygen,
argon being a little heavier and nitrogen a little lighter; but here
the similarity ends. Oxygen is what we call a very active substance.
As we have seen, it causes things to burn very much more rapidly in it
than in air. Nitrogen and argon, on the contrary, put out fire. If a
lighted candle is put into a jar of nitrogen or argon its flame will be
extinguished as quickly as if put into water.
We must now consider the impurities found in air. Of these the most
important is carbonic acid gas, or, as it is frequently called, carbon
dioxide. It is always produced when wood or coal is burned, and
is, of course, constantly being poured out of chimneys. It is also
produced in our lungs and we give off some of it when we breathe. It
is colorless, like the gases found in pure air, has no odor or taste,
and is considerably heavier than oxygen or nitrogen. In its other
properties it is much more like nitrogen than oxygen, for when a
candle is put into it the flame is extinguished at once. To find out
whether air contains carbonic acid gas, it is only necessary to force
it through a little lime water, in a glass vessel, and watch what
change takes place in the water. Fresh lime water is as clear as pure
water; but after forcing air containing carbonic acid through it, it
becomes turbid and milky. If the turbid water is allowed to stand for
a time, a white powder will settle to the bottom, and if we examine
this powder, we find it to be very much the same thing as chalk. While
it is true that air generally contains only a very small portion of
carbonic acid gas, there are some places in which it is present in such
large quantities as to render the air unfit for breathing. The air at
the bottom of deep mines and old wells often has an unusually large
proportion of this gas, which, because of its great weight, accumulates
at the bottom, and remains confined there. The presence of a dangerous
quantity of the gas in such places may be detected by lowering a candle
into it.
Why Does the Scenery Appear to Move When We Are Riding in a Train?
When you sit in a moving train looking out of the window it appears
as though the fields, the telegraph poles and everything else outside
were moving, instead of you. This is because our only ideas of motion
are arrived at by comparison, and the fact that neither you nor the
seats of the car or any other part of the inside of the car is changing
its position, leads you to the delusion that the things outside the
car are moving and not you. If you were to pull down all the curtains
and the train were making no noise at all, you would not think that
anything was moving. It would appear as though you were motionless just
as everything in the car appears so. When you turn then to the window,
and lift the curtain you carry in the back of your mind the idea of
being at rest and that is what makes it appear as though the fields and
everything outside were moving in an opposite direction.
This is particularly noticeable when you are in a train in a station
with another train on the next track. There is a sense of motion if one
of the trains only is moving and you feel that it is the other train,
because you are surrounded by objects in the car which are at rest,
and when you look out at the other train with this half consciousness
of rest in your mind, it appears as though the other train were moving
when as a matter of fact it is your train. If the delusion happens to
be turned the other way, it will appear as though you are moving and
the other is still. It depends upon what cause the impression starts
with.
Why Don’t the Scenery Appear to Move When I am in a Street Car?
If you are in a street car in the country and moving along fast you
will receive the same impression, especially in a closed car, because
you are looking out of one hole or one window. In an open car you
do not receive the same impression because your range of vision is
broader. You can and do, although perhaps unconsciously, look out on
both sides and the impression your mind gets through the eyes is not
the same. If you were to pull down all the storm curtains in a moving
open street car, and then look out of one little crack, you would think
the outside was moving. But if you stop to remember that you are moving
and not the things outside the car, then the impression vanishes. In
the city, of course, your brain is so thoroughly impressed with the
fact that houses and pavements do not move, and the cars move so much
more slowly, that it is difficult to make yourself believe otherwise.
The impression is more difficult always when you are moving through
or past objects with which you are perfectly familiar. It is all, of
course, a question of impressions.
Why Does the Moon Travel With Us When We Walk or Ride?
The moon does not really travel with us. It only seems to do so. The
moon is so far away that when we walk a block or two or a hundred, we
cannot notice any relative difference in the relative positions of the
moon and ourselves. When a thing is close at hand we can notice every
change in our position toward it, but when it is far away the change of
our position toward it is so slight that it is hardly perceptible. A
very good way to illustrate this is to ask you to recall the last time
you were in a railroad train looking out at the scenery in the country.
The telegraph poles rush past you so fast you cannot count them. The
cows in the pasture beside the railroad do not seem to go by so fast.
You can count them easily. The tree farther over in the next field does
not appear to be moving but slightly, while the church steeple which
you can see far in the distance, does not go out of sight for a long
time--in fact, seems almost to be moving along with you. The moon is
just like the church steeple in this case, except that it is so much
farther away that it seems to travel right with you. It is all due to
the fact as stated at the beginning of this answer, that the relative
positions of yourself and the moon are only slightly changed as you
move from place to place, so slight in fact as to appear imperceptible.
Is There a Man in the Moon?
The markings which we see on the face of the moon when it is full can
by a stretch of the imagination be said to form the face of a man. On
some nights this face appears to be quite distinct. If, however, we
look at the moon through a telescope, we see distinctly that it is
not the face of a man. Through a very large telescope we can see very
plainly that the marks are mountains and craters of extinct volcanoes.
It just happens that these marks on the moon, aided by the reflections
of the light from the sun, which gives the moon all the light it has,
make a combination that looks like a face.
Does the Air Surrounding the Earth Move With It?
This is one of the old puzzling questions which many a high-school
student has had to struggle with to the great amusement of the teacher
who asks for the information and such other scholars who have already
had the experience of trying to solve it.
To get at the right answer you have merely to ask one other question.
If the air does not revolve with the earth, why can’t I go up in
a balloon at New York, and stay up long enough for the earth to
revolve on its axis beneath me, and come down again when the city of
San Francisco appears under the balloon, which should be in about
four hours? If that were possible, travel would be both rapid and
comfortable, for then we could sit quietly in a balloon while the earth
traveling beneath us would get all the bumps.
No, the atmosphere surrounding the earth moves right along with the
earth on its axis. If it were not so, the earth would probably burn
up--at least no living thing could remain on it--since the friction of
the surface of the air against the surface of the earth would develop
such a heat that nothing could live in it.
Why Does Oiling the Axle Make the Wheel Turn More Easily?
If you look at what appears to be a perfectly smooth axle on a bicycle
or motor car through a powerful magnifying glass, you will find that
the surface of the axle is not smooth at all, as you may have thought,
but covered with what appear to be quite large bumps or irregularities
in the surface. If you were to examine the inside of the hub of the
wheel in the same way, you would find that it also is like that. Now,
when you attempt to turn a wheel on the axle without oil, these little
irregularities or bumps grind against each other, producing what we
call friction. As friction develops heat, the metal of the axle and the
hub expand and the wheel gets stuck.
What Made the Mountains?
There is no question but that at one time the surface of the earth was
smooth, i. e., there were no big hills and no deep valleys. That was
before the mountains were made. The earth was a hot molten mass that
began to cool off from the outside inward. It is still a hot molten
mass inside today. The outside crust became cooler and cooler and the
crust became deeper and deeper all the time. Then when there would be
an eruption of the red-hot mass inside, the earth’s crust would be
bulged out in some places and sucked in in others and would stay that
way. The bulged out place became a range of mountains and the sucked
in place became a valley. This process went on happening over and over
again until the crust of the earth became firmly set. Volcanos caused
some of these eruptions, as also did earthquakes. There are today
gradual changes occurring which to a certain extent change the outside
surface of the earth, and it is possible that new mountain ranges will
be produced in this way.
What Makes the Sea Roar?
The roar of the sea is a movement of the sea which causes the same kind
of air waves or sound waves that you make when you shout, excepting
that, of course, the vibrations do not occur so quickly in the sea and,
therefore, the sound produced is a low sound. It is no different in
any sense than the same noise would be if the same air waves could be
produced on the land away from the water.
Why Is Fire Hot?
When a fire is lighted it throws off what we call heat rays or waves.
These waves are very much like the waves of light which come from a
light or fire or the air waves which produce sounds. The rays of light
and heat which come from the sun are like the rays of light and heat
from a fire. Heat is of two kinds--heat proper which is resident in the
body, and radiant heat which is the kind which comes to us from the
sun or from a fire. This radiant heat is not heat at all, but a form
of wave motion thrown out by the vibrations in the ether. The heat we
feel is the sensation produced upon our skins when it comes in contact
with the waves created by the fire. Heat was formerly thought to be an
actual substance, but we know now that radiant heat is known to be the
energy of heat transferred to the ether which fills all of space and is
in all bodies also. The hot body which sets the particles of either in
vibration and this vibrating motion in the form of waves travels in all
directions. When these vibrations strike against our skin they produce
a heat sensation; striking other objects these vibrations may produce
instead of a heat sensation, either chemical action or luminosity. This
is determined by the length of the vibratory rays in each case.
When I Throw a Ball Into the Air While Walking, Why Does It Follow Me?
When you throw a ball into the air while moving your body forward or
backward, either slowly or fast, the ball partakes of two motions--the
one upward and the forward or backward motion of your body. The ball
possessed the motion of your body before it left your hand to go up
into the air because your body was moving before you threw it up, and
the ball was a part of you at the time.
If you are moving forward up to the time you throw the ball into the
air and stop as soon as you let go of the ball, it will fall at some
distance from you. Also if you throw the ball up from a standing
position and move forward as soon as the ball leaves your hand the ball
will fall behind you, provided you actually threw it straight up.
Of course, you know that the earth is moving many miles per hour on
its axis and that when you throw a ball straight into the air from a
standing position, the earth and yourself as well as the ball move
with the earth a long distance before the ball comes down again. The
relative position is, however, the same. We get our sense of motion by
a comparison with other objects. If you are in a train that is moving
swiftly and another train goes by in the opposite direction moving just
as fast, you seem to be going twice as fast as you really are. If the
train on the other track, however, is going at the same rate of speed
and in the same direction as you are, you will appear to be standing
still.
Going back to the ball again, you will find that it always partakes of
the motion of the body holding it in addition to the motion given when
it is thrown up.
What Good Are the Lines On the Palms of Our Hands?
It cannot be said that the lines on the palms of our hands are of any
great service to us. Indeed it is doubtful if they are of any value
in themselves, outside of the possible aid they may be in helping us
to determine the character of the surface of things which we grasp or
touch. It is possible that they aid in some slight degree in this way.
There is little doubt, however, that they are a result of the work the
hands are constantly called upon to do rather than contrived for any
particular service. The habitual tendency of the fingers in grasping
and holding things throws the skin of the palms into creases which
through frequent repetition make the lines of the palms permanent in
several instances.
The peculiarities of these lines or creases in various individuals
as to details and length and variations is the chief basis of the
so-called science of palmistry.
What Makes Things Whirl Round When I Am Dizzy?
The medical term that describes this condition of turning or whirling
is vertigo, which means in simple language “to turn.” There are two
kinds of dizziness--one where the objects about us seem to be turning
round and round and the other where the person who is dizzy seems to
himself to be turning round and round.
One cause of this is due to the fact that when you are dizzy the
eyes are not in complete control of the brain and the eyes moving
independently of each other look in different directions and produce
this turning effect on the brain, since each eye then sends a different
impression to the brain instantly.
The principal cause of the sense of dizziness is, however, the little
organ which gives us our power to balance and which is located near the
ears. Sometimes this organ becomes diseased and people affected in this
way are almost continually dizzy. Whenever this organ of balance is
disturbed we lose our idea of balance and the turning sensation occurs.
It is easy to make yourself dizzy. All you do is to turn round a few
times in the same direction and stop. In doing this you disturb the
little organ of balance and things begin to turn apparently before your
eyes. If you turn the other way you right matters again or if you just
stand still matters will right themselves. There is no great harm in
making yourself dizzy and very little fun.
Why Are the Complexions of Some People Light and Others Dark?
This difference in the complexions of people is due to the varying
amounts of pigment or coloring material in the cells of which the skins
of all animals is made up. Very light people have very little pigment;
very dark people, those with dark eyes and black hair, have a great
deal of this coloring material in their cells. A great many people are
neither light or very dark. They have less than the dark-complexioned
people and more than the light-complexioned people. When the hair
turns gray it is because the pigment has disappeared. As this is due
to the loss of this coloring material, dark-complexioned people turn
gray sooner than light-complexioned people. The structure of the skin
showing how these cells are made in layers can be seen by examining the
skin with a microscope.
What Makes Me Tired?
Men were wrong for a long time in their conclusions as to what produced
the tired feeling in us.
We know now that every activity of our body registers itself on the
brain. When we move an arm or leg a great many times we soon feel
tired. Every time you move your arm the movement is registered in the
brain, and after a number of these movements are registered the tired
feeling in the arm appears. It is said that every movement of any part
of the body really produces certain defective cells and that these
accumulate in the blood. When these reach a certain number the tired
feeling takes possession of us, and when we rest, the blood under
the guidance of the brain, goes to work and rebuilds these defective
cells. We know that a change takes place in the blood when we become
tired because, if you take some of the blood from an animal that shows
unmistakable signs of fatigue and inject it into an animal that shows
no tired feeling at all, the second animal will begin to show signs of
fatigue even though it is not active at all.
We used to think that being tired indicated that our bodies were in
need of food and that the way to overcome it was to eat a big meal.
We did not stop to think that even when we are hungry the human body
has sufficient food supply stored up to keep it going for days without
taking in new food. Of course, this mistake was made because we knew
that our power and energy came as a result of the food we took into our
systems, but this belief was exploded when it was found that a really
tired person could hardly digest food while tired, and that it is best
for people who are very tired to eat only a light meal.
Why Are Most People Right-Handed?
Most people are right-handed because they are trained that way. Being
right-handed or left-handed depends largely on how we get started in
that connection. When we are young we form the habit generally of
being either right-handed or left-handed, as the case may be. Most
people correct their children when it appears they are likely to
become left-handed, as we have come to think that it is better to be
right-handed than left, and that is the reason why most people are
right-handed. As a matter of fact, if we were trained perfectly, we
should all be both right-handed and left-handed also. Some people are
so trained and, when we refer to their ability to do things equally
well with both hands and wish to bring out this fact, we say they are
ambidextrous. It is not natural that one hand should be trained to do
things while the other is not.
Why Are Some Faculties Stronger Than Others?
All of our senses are capable of being developed so that our ability
along these lines would be about equal. The trouble is that we soon
begin to develop one or more of our faculties in an unusual manner at
the expense of the development of others. Many people have a keener
sense of observation than others because they have had more and better
training along that line. It is a pity that more attention is not given
to the development of the power of observation in children, because
it is one of the most valuable accomplishments that we can possess
ourselves of. With the sense of observation developed to the highest
degree, many of the other faculties need not be developed so strongly
because, if we notice every thing that it is possible for us to see,
we do not have the need of the development of other powers to the same
extent.
It is said that it would be possible to so train an infant and bring
him up to maturity with all his faculties developed and in practically
an even way. If we did that we would have a wonderfully intelligent
being.
[Illustration: Glazing plates.]
[Illustration: Decorating china cups.]