SUNLIGHT AND SHADOW.
It was a busy time on the farm. Only when the day's work was over and
they were gathered in the sitting-room was there time for the long talks
with Uncle Robert that they all enjoyed so much.
"It's wonderful," said Mr. Leonard one evening, looking up from his
paper, "how fast the corn is growing. Even the late planting is coming
on."
"That's because the weather is so warm," said Donald.
"I wonder what makes it warm?" said Uncle Robert.
"Why, Uncle Robert," exclaimed Susie, "it's spring! That's what makes it
warm."
"But what makes it spring, little girl?" asked Uncle Robert.
"Why, it is always spring in May," said Susie.
"I know of a country where it is spring in September," replied Uncle
Robert.
"How can it be?" asked Susie. "I thought springtime always came in May."
"What makes us know that it is spring?" asked Uncle Robert.
"Oh, it gets warmer all the time. The birds come, things begin to grow,
and the flowers bloom."
"But what makes all this happen just now?"
"It's the sun," answered Donald from the floor, where he was playing
with his great St. Bernard dog, Barri. "You know it rises earlier and
sets later every day now than it did a while ago. It's hotter too."
"It goes higher at noon," said Frank. "In the middle of summer it is
almost straight over our heads, and in the winter it seems ever so much
farther to the south. I've often noticed that."
"So have I," said Donald. "And in the winter the shadows are longer than
they are in summer. It must be because the sun isn't so high up."
"Aren't shadows funny?" said Susie. "One day when I was coming in to
dinner, just for fun I tried to walk on my shadow, and I could step on
my head."
"I've done that lots of times," said Donald. "But it's a strange thing.
Sometimes I can step clear over my head--I mean in the shadow--and then
again I have to step on it."
"And when you jump," said Susie, "it spoils it. The shadow always jumps
too."
"What kind of weather was it when you had to jump to it?" asked Uncle
Robert.
"I don't remember," said Donald. "Would the weather make any
difference?"
"I remember," said Susie, "because one time when I was jumping that way
I fell down and was almost buried in the snow.
"Then it was winter, wasn't it?" asked Uncle Robert.
"It must have been," said Frank.
[Illustration: Shadow stick.]
"And since you told us that the shadows at noon tell why it is warmer in
summer than in winter I've been watching them. They get shorter all the
time." "How would you like to measure the shadows every day," said Uncle
Robert, "and see if you can find out when they are shortest and when
they are longest?"
"How can we?" asked Susie. "Shadows are so queer."
"Yes," said Uncle Robert, "shadows are queer, but, if we take one that
doesn't jump as yours does, don't you think we can measure it?"
"Of course we can," said Frank. "We can use the house. That always
stands still."
"The house might do," said Uncle Robert; "but wouldn't it be better to
have a shadow stick?"
"Where can we get one?" asked Donald.
"What is it made of?" asked Frank.
"It is like this," said Uncle Robert, taking paper and pencil from his
pocket. "There is one long piece of board, and one short one nailed to
the end--so," drawing it on the paper.
"Oh, that's easy enough made," said Donald. "We can do it ourselves
right here in the tool house."
"Let's make it to-morrow, Don," said Frank.
"It must be set up some place with the upright end turned toward the
south, so that just at noon the shadow of the short piece may fall
straight on the board. By drawing a line across the board at the top of
the shadow and marking the date on it, we can tell how the length of the
shadow changes."
"Uncle," asked Donald, "when it is winter here, is it summer in some
other part of the world?"
"Yes," was the reply, "and now that our summer is coming, the people
there are beginning to have winter."
"Then," said Frank, "when it gets cooler here in the fall it is growing
warmer there, and that would make their spring come in September,
wouldn't it? Do you see, Susie?"
[Illustration: Eskimo scene.]
"Yes," answered Susie, "but it seems all mixed up. I thought it was the
same as it is here all over the world."
"Oh, I didn't," said Donald. "I've read about countries where it is
summer all the time, and is so hot that the people don't do anything but
lie under the trees and sleep. And there are other countries where it is
winter all the time, and the people dress in furs and make their houses
of snow and ice. I read all about it in a book once, but it didn't tell
why it was so. I knew, of course, the sun had something to do with it."
"Why, you know, Don," said Frank, "we learned all that in our geography
at school."
"Yes," said Donald, "but I never thought about that in the geography as
meaning any real country."
"What did you think it meant?" asked Uncle Robert.
"Oh," said Donald, "just a lesson in the book."
"Well," said Frank, "I always thought it was some country, but I never
knew where. I didn't think much about it after I said the lesson."
"I should think not," said Uncle Robert, not sorry that the teacher had
gone away and the school had been closed.
"I wish when books tell things they'd tell why they're so," said Frank.
"Perhaps if we think about these things," said Uncle Robert, "we may be
able to answer some of the 'whys' for ourselves."
"We can tell by the thermometer just how warm it is every day," said
Susie, "but it won't tell us why."
"The shadow stick may help us there," said Uncle Robert.
"I am afraid I shall forget," said Donald.
"I have some little notebooks in my trunk," said Uncle Robert. "Suppose
I give you each one and let you write down what the thermometer and the
shadow stick say every day."
"What fun that'll be!" cried Susie. "When may we begin?"
"To-morrow morning, if you like," replied her uncle. "I will get the
books for you now."
He went away to his room, and soon returned with the notebooks.
"I'll tell you, uncle," said Frank as he thanked Uncle Robert for his
book, "how would it do for each of us to look at the thermometer at a
different time of the day?"
"The very thing!" replied Uncle Robert, well pleased. "You are always up
early, Frank, so suppose you look at six in the morning, Susie at twelve
o'clock, and Donald at six in the evening. How will that do? Then we
shall have the record for the whole day."
"I think it will be such fun!" said Susie. "I wonder if our books will
be very different."
"What makes you think they will be different?" asked Uncle Robert.
"It's always hotter at noon than it is at night or in the morning," said
Susie.
"Do you know," said Uncle Robert, "there are places all over the United
States where such records are kept? They are published, and I am to have
them sent to me every week."
"I wonder if ours will be like them," said Donald, turning over the
pages of his notebook.
"Even if they should be different." said Uncle Robert, "they may be just
as true."
"We'll get up early and start the shadow stick the first thing in the
morning," said Frank, "so as to have it ready by noon."
"How do you know when it is noon?" asked Uncle Robert.
"We look at the clock," said Susie.
"But noon by the clock is not always noon by the sun," replied Uncle
Robert.
"How can that be?" asked Donald.
"It is noon somewhere on the globe every minute of the twenty-four
hours," said Uncle Robert. "The sun is always setting and always rising
somewhere."
The children were puzzled.
"I don't see how that is," said Donald.
"Let us see if we can find out," said Uncle Robert. "Frank, you stand at
the east end of the room, Donald at the west, and Susie in the middle.
Now, we'll play that Frank is in New York, Susie here at home in
Illinois, and Donald in Denver. I'll take the lamp and be the sun. You
are shadow sticks, you know. Now watch the shadows, and see when they
point directly north."
Uncle Robert took the lamp and walked slowly from the east side of the
room.
"My shadow points north," said Frank as Uncle Robert passed him.
"Now mine does," said Susie.
"And mine last of all," said Donald.
Uncle Robert took out his watch. It was ten minutes past eight.
"That is Susie's time," he said. "Would it be the same in New York,
Frank?"
"I think it would be past that," said Frank, "but I don't know how
much."
"It is ten minutes past nine by the watch in New York," said Uncle
Robert.
"When would it be that time in Denver?" asked Donald.
"In an hour by the watch," said Uncle Robert, "but it would not be the
same by the sun."
"Then the watches don't tell the true time, do they?" said Frank.
"The sun's shadows give us the true time," said Uncle Robert. "We will
study the shadows, and by and by may learn how the watches and clocks
are regulated. But how do you think people told the time before they had
clocks?"
"It must have been by the sun," replied Frank.
"I can tell by the sun when it is noon," said Donald, "but I don't see
how any one can tell any other hour that way."
"How do you know when it is noon?"
"Why, the sun is highest at noon." said Donald. "and the shadows point
straight toward the north."
"Early in the morning they point to the west," said Frank, "and in the
evening they point to the east."
"The people who lived in the world many hundred years ago observed the
same thing," said Uncle Robert. "There was nothing so strange to them as
the rising and setting of the sun. They loved the light that came with
it. They feared the darkness that followed its going away. They told
many interesting stories to explain this continued appearance and
disappearance. Some thought the sun was a king riding through the sky in
a golden chariot. Others looked upon it as a god and worshiped it.
"They soon learned that when it went away it was sure to come again, and
as they saw how regularly it moved, they felt there must be some power
back of it to guide it. Through this they were led to a belief in a Being
that controlled all things.
"They watched the shadows, too, and saw them change just as you see them
every day. They learned that the shadow is shortest when the day is half
gone, and they called that time midday. So, by studying the length and
direction of the shadows, they soon became able to judge the time of
day.
"Then some one thought to set up a rod and mark the places where the
shadow fell at sunrise, at sunset, and at midday. The space in between
was divided for the hours. This was called a sun dial and was the first
instrument ever made for telling time."
"When was the first one made?" asked Frank.
"That is not known," replied Uncle Robert, "but we read in the Bible of
the sun dial of King Ahaz, who lived about eight hundred years before
the time of Christ. That is the first record we have of one."
"How was it made?" asked Donald.
"I do not know how the one King Ahaz used was made," said Uncle Robert,
"but I can show you how one looked that I saw in an old garden in
England. This," drawing a half circle, "is the dial on which
the hours were marked. Around this dial there was a border, much
cracked, and crumbling away, but I could read the words, 'The sun guides
me, the shadow you.' The rod, or gnomon, as it is sometimes called,
stood just halfway between the ends. Where would the noon shadow fall,
Susie?"
[Illustration]
"In the middle, wouldn't it?" answered Susie.
"And the morning shadow would fall on the west and the evening shadow on
the east side," said Frank.
"Now we'll put in the shadow stick," said Uncle Robert, drawing a
triangle on the paper.
"Why don't you make it stand up straight?" asked Donald.
"The shadow does not tell the truth," said Uncle Robert, "unless it
points in the same way that the north pole does, and that, we know,
points to the north star. I will explain this some other time."
"Couldn't we make a sun dial?" asked Donald. "I don't believe it would
be very hard."
"You could make one easily," answered Uncle Robert.
"But let's have the shadow stick first," said Frank.
Susie went to the window and looked out at the clear star-lighted sky.
"Uncle," she said, "the stars all look alike to me, only some are little
and some are big. How can people know them by their names?"
"Just as anything else is known, dear," replied Uncle Robert, "by close
and careful study."
"I wish we could study the stars," said Frank.
"We will some time," replied Uncle Robert. "Come out on the piazza now,
and I will show you the north star. That will be a good beginning."