[Illustration: NEW YORK CITY HALL]
Where Does the Day Begin?
To understand this subject we must first appreciate that a day as we
think of it is a division of time made by man for the purpose of his
own reckoning. So far as the beginning of day is concerned, it begins
at a different place in the world every hour; yes, every minute and
every second in the day. As, however, the distance in feet where the
day begins from one minute to another is so short that we can hardly
notice it in such short measurements of time, we will look at the
answer to the question from hour to hour. When you understand the
subject from that point you can yourself see that the day actually
begins at a different point of the earth every minute and every second
of time.
How Much of the Earth Does the Sun Shine on at One Time?
The sun is shining on some part of the earth all the time and the
shining of the sun makes the difference between day and night. Wherever
the sun is shining it is day-time, and where the sun is not shining it
is night-time.
To illustrate we will make use of an ordinary orange and a lighted gas
jet. Let us take a long hat-pin and stick it through the orange from
stem to stem. Now hold the orange by the ends of the hat-pin up before
the lighted gas jet. You will notice that one-half of the orange is
lighted, while the other half is dark. Of course, it is the half of the
orange away from the light that is dark. Now, revolve the orange slowly
on the hat-pin axis toward the light. When you have turned the orange
half way round the part that was formerly dark is now lighted up and
the other part is now dark.
Now examine closely and you will see that just one-half of the orange
is lighted at one time and the other half is dark. You revolve the
orange in front of the light slowly and a portion of the surface of the
orange is always coming into the light, while a corresponding portion
of it on the opposite side is constantly going into the dark. In other
words, whatever the speed at which you revolve the orange toward the
light, one-half of it is always light and the other half is always dark.
This is exactly what happens in the relation of the earth to the sun
every day. One-half of the earth, which is continually revolving on
its axis, is facing the sun, and is, therefore, in the daylight, while
the other half of the earth’s surface is in darkness, because the
light from the sun does not strike any portion of it. If the earth
did not revolve one-half of it would always be in day-time, while the
other half would be continually having night-time. As the earth is
always moving or revolving the half where it is day-time is constantly
changing, so that the day is beginning on one-half of the earth’s
surface every second of the day. Actually, of course, then, if you live
on the east side of town day begins with you a little sooner than with
your chum who lives on the west side of town. We have come to measure
the beginning of day as sunrise and the beginning of night as sunset,
wherever we happen to be.
For convenience in setting clocks and in measuring time we do not take
into consideration these very slight differences in the rising and
setting of the sun, but set our clocks all alike in different parts
of the same town or city to avoid confusion. In fact, in order to
overcome the difficulties and confusions arising in reckoning the time
of the clock in different localities, and still keep the beginning of
what we call day-time constant with the hands of the clock, we have
agreed upon what we call standard time. We agreed upon this system
of fixing standard time because the actual sun time by which people
set their clocks up to a few years ago led to so many mistakes in
catching trains, keeping engagements and other misunderstandings where
the question of time was involved. Then when this system of standard
time was adopted the confusion became even worse, and the mistakes and
misses more numerous, because some people insisted on setting their
clocks to standard time and others insisted on sticking to the old sun
time schedule. So you could never tell by looking at the clock what
time it really was unless they put a sign on the clock saying what kind
of time they were going by. Finally, however, most of the people came
to appreciate that it would be a good idea to use one uniform system of
setting the clocks and of having them in harmony in a sense with the
other clocks in the world, and the adoption of the standard time plan
became universal. To make this system practical and effective, certain
points about equally distant from each other were selected, at which
point
Where Is the Hour Changed?
the hour would change for all points within that zone. Under this
system all timepieces in any one zone point to the same hour. So the
clock time changes only as you go east or west. All points on a north
and south line have the same time as the zone in which it is located.
For convenience in adjusting the time in America the country was
divided into four east and west zones. The first zone takes in
everything on a straight north and south line east of Pittsburg, and is
called Eastern time. The second zone extends from Pittsburg to Chicago,
and is called Central time; the third zone extends from Chicago to
Denver, and is called Mountain time; while the fourth zone extends
from Denver to the Pacific Ocean. These selections were made because
the sun actually rises about one hour later in Pittsburg than in New
York; one hour later in Chicago than in Pittsburg; one hour later in
Denver than in Chicago, and one hour later on the Pacific Coast than in
Denver. Under this plan when it is nine o’clock in New York it is only
eight o’clock at Pittsburg and all points in the Central zone; seven
o’clock in all points in the Mountain zone; six o’clock in Denver and
five o’clock in San Francisco. As you keep travelling westward you drop
one hour of the clock time in every zone, and as under this system the
earth’s east to west distance is divided into twenty-four such zones,
if you went west entirely around the world you would lose a whole day
of clock time.
If, however, you went around the world from west to east in the same
manner you would gain a whole day.
Where Does the Day Change?
This system of agreeing on fixed places where the hour changes made it
necessary to also fix a point where for the purposes of the calendar
the day also changes. This imaginary north and south line is fixed
upon at 180 degrees west longitude, which would cut the Pacific Ocean
in two. This line makes it possible for a person to travel all day
before approaching this line and then find himself after crossing it
travelling all the next day with the same name for the day of the week.
Thus he could spend all of Sunday travelling toward the International
Day Line, as this is called, and after crossing it spend another
Sunday, which would be the next day, going away from it. This would
give him the novel experience of having two Sundays on successive days.
The same thing would happen if he were travelling to the Day Line on
Monday, Tuesday, Wednesday, Thursday, Friday or Saturday. He would live
through two succeeding days of the same name in the same week, one
right after the other. This would be in going westward.
If you were traveling eastward and crossed the International Day Line
on Sunday at midnight you would lose a day completely out of the week,
for when you woke up the next morning it would be Tuesday.
Why Do We Cook the Things We Eat?
We have several reasons for doing this. The first and most important
reason to us is that the application of heat to food makes it more
easy to digest. Other reasons are that when cooked our food is more
palatable; the process of cooking kills all microbes, which, if taken
into our bodies alive, would give us diseases, and also it is easier
for us to chew food that has been cooked.
[Illustration: WONDERS PERFORMED BY ELECTRIC LIFT MAGNET
This picture shows the construction of a successful electric lift
magnet. This device, by means of magnetic attraction, fastens itself
to practically all kinds of iron and steel without the aid of slings,
cables or chains.]