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V.14

ARTES
1817.
SCIENTIA
LIBRARY
VERITAS
OF THE
UNIVERSITY OF MICHIGAN
TUEBOR
SI QUERS PENINSULAM AMUNAN
CIRCUMSPICE
THE GIFT OF
Mrs. Fred Holton
A 13172r
828
1868
V. 14

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ROLLO'S
PHILOSOPHY.
[SKY.]
THE ROLLO SERIES
COMFOSED OF FOURTEEN VOLUMES, VIE
Rollo Learning to Talk.
Rollo Learning to Read.
Rollo at Work.
Rollo at Play.
Rollo at School.
Rollo's Vacation.
Kollo's Experiments.
Rollo's Museum.
Rollo's Travels.
Rollo's Correspondence.
Rollo's Philosophy-Wats
Kollo's Philosophy-Air.
Rollo's Philosophy-Fire.
Rollo's Philosophy-Sky.
A NEW EDITION, REVISED BY THE AUTHOR
NEW YORK:
SHELDON & COMPANY, PUBLISHERS,
498 & 500 BROADWAY.
1868%.
+
Eaterea, according to Act of Congress, in the Year 1888, 1
LOLLIPS SAMPSON, & CL
he Clerk's Utics of the District Court of the District of Massachusetia

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8k
Mrs Fred Hallon
5-27-42
PREFACE.
THE man design in view, in the discussions
which are offered to the juvenile world, under the
title of THE ROLLO PHILOSOPHY, relates rather t
their effect upon the little reader's habits of think-
ing, reasoning, and observation, than to the ad
ditions they may make to his stock of knowledge
The benefit which the author intends that the
reader shall derive from them, is an influence on
the cast of his intellectual character, which is re-
ceiving its permanent form during the years to
which these writings are adapted.
The acquisition of knowledge, however, though
in this case a secondary, is by no means an unim
portant, object; and the discussion of the several
topics proceeds accordingly, with regularity, upon
a certain system of classification. This classifica-
tion is based upon the more obvious external prop.
erties and relations of matter, and less upon those
1 *
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.
:
6
PREFACE.
which, though they are more extensive and gen
eral in their nature, and, therefore, more suitable.
in a strictly-scientific point of view, for the four-
dations of a system, are less apparent, and require
higher powers of generalization and abstraction;
and are, therefore, less in accordance with the
genius and spirit of the Rollo philosophy.
As teachers have, in some cases, done the
author the honor to introduce. some of the pre-
ceding works of this class into their schools, as
reading books, &c., considerable reference has
been had to this, in the form and manner of the
discussion, and questions have been added to facil-
itate the use of the books in cases where parents
or teachers may make the reading of them a regu
lar exercise of instruction
'י


CONTENTS.
UPTICAL ILLUSIONS,..
CHAPTER 1.
Fage.
CHAPTER II.
THE PROOF,..
24
CHAPTER III.

APPARENT MAGNITUDE,.
37
CHAPTER IV.
DEGREES..
CHAPTER V.
CLOUDS,
. 64
CHAPTER VI.
THE MOVING RAINBOW,.
.78
CHAPTER VIL
THE DEW-Drop,.
99
8
CONTENTS.
CHAPTER VIII.
Page
POLES OF REVOLUTION,.
103
CHAPTER IX.
RESPONSIBILITY,.
118
CHAPTER X.
THE GREAT BEAR,..
129
CHAPTER XI.
(39
ORION,.
CHAPTER XII.
SIRIUS,
152
CHAPTER XIII.
PARALLAX,.
162
CHAPTER XIV.
The Aurora BOREALIS,.
187


THE
ROLLO PHILOSOPHY
THE SKY.
CHAPTER I.
OPTICAL ILLUSIONS.
ONE day Rollo and his father were return
ing home in a wagon from a ride which they
had been taking into the woods. It was
quite a large wagon, with two seats. Jonas
and little Nathan were upon the front seat,
and Rollo and his father sat behind. They
had been to get some trees to set out near
the house. There was a little spot north of
the house, where Mr. Holiday thought that
a group of trees would make the landscape
more pleasant as seen from the parlor win-
dows. So he had had the ground prepared,
and he used to drive ou, now and then to
10
THE SKY.
4th
get trees to plant there. The trees which
they had got were in the bottom of the
wagon, with the tops running out behina.
There were a few small evergreens standing
up in the bottom of the wagon.
When they had got about half way home,
the sky became overcast with heavy, black
clouds. They were very black, and Mr.
Holiday thought that a shower was coming,
and that the whole party would get drenched
with rain. But the rain did not come on as
they expected, and Rollo leaned back in the
wagon, and looked up, in admiration of the
vast canopy of clouds which spread over the
whole heavens like a dark dome.
"What a great black arch!" said Rollo.
"Yes," replied his father;
"though it
is a dome, rather than an arch. Do you
know what the difference is between a dome
and an arch?”
"No, sir," said Rollo, "not exactly."
“An arch,” replied his father, "is straight
on the two sides, and curves only from one
side over to the other; but a dome is round,
and curves from every side to a point at the
top, like the under side of a bowl."
•
OPTICAL ILLUSIONS.
"Yes, sir," said Rollo, "I understand.
So the sky is a dome?"
"Yes," replied his father, "though it is
often called an arch. But an arch is straight
at the two sides, and open at the ends. Do
you remember the arches under the chim-
neys in our cellar?”
"Yes, sir, I remember the arches down
cellar; are they under the chimneys?"
66
"Yes," replied his father. 'A chimney
s generally supported by an arch below, in
he cellar. It wouldn't do to begin to build
chimney on the floor of the house. Thev
must begin on the ground, at the bottom of
the cellar."
"Why, sir?" said Rollo.
"Because," replied his father, "a chimney
is very heavy very heavy indeed. Such
a column of bricks, extending from the lowest
fireplace away up above the roof of the house,
would be too great a weight to rest upon the
boards and timbers of a floor. So they begin
at the bottom.
"But, then," continued his father, "it is
not necessary to build it up solid from the
botim. They build two walls, as far apart
as the width of the chimney, and then they
11
-
12
THE SKY.
archi over from one of these walls to the
other, and so found the chimney upon the
arch. This saves room in the cellar; fo
they generally make a little closet in the
arch, which is a very convenient place to
keep things warm; and, besides, it saves
bricks. It would take a great many more
bricks to build up a foundation for the
chimney solid from the bottom."
99
"And it saves work too," said Rollo, "I
suppose, in laying the bricks."
"Yes," said his father; "so it is better on
all accounts. For the arch is very strong-
almost as strong as solid work. But you seo
it is quite different from a dome. The space
covered by an arch is square or oblong,
while that covered by a dome is round."
"Do they make domes in building
houses?" asked Rollo.
An
"No," replied his father. "I believe not,
unless we consider an oven a dome.
oven,is a sort of a dome; that is, it is built
on the same principle, only it is oval in
its form, instead of round."
During this conversation, Jonas had been
driving pretty fast, because he expected that
it was going to rain; but now he began to
OPTICAL ILLUSIONS.
13
?།
et the horse slacken his pace a little, as he
thought, from the appearance of the clouds,
that there would be no rain; and driving
very fast seemed to shake the trees and
plants so as to threaten to do them some
injury.
After a short pause, Mr. Holiday spoke of
the subject again. He said, -
"The dome-like appearance of the sky is
one of the most remarkable optical illusions
in nature."
"What is an optical illusion?" said
Rollo.
"An optical illusion?" repeated his father;
-"why, it is a kind of a false appearance
which any thing makes; such, for instance,
as two long rows of trees appearing to come
pretty near together at the farther end, while
they are really as far apart at that end as
they are where we stand. That is an optical
illusion.
"So," continued his father, "if you were
to put your finger in a tumuler of water, and
let Nathan look at it through the side of the
tumbler, it would look very large to him;
that is, if you were to put your finger down
about in the middle of the tumbler. He

2
14
THE SKY.
would say, perhaps, 'O, what a monstrous
great finger!' and you would say, 'No, Na-
than, it is only my finger. Its looking large
is only an optical illusion.'”
"What would make it look so large, sir?
said Nathan.
"The water,
and the glass side of the
tumbler," replied his father.
"But does every thing look large if we
see it through water?" asked Rollo.
“No,” said his father. "It depends upon
how you look at it, and the shape of the
glass that the water is in. If you run a
stick down a little way into the water in a
brook or pond, it makes the stick look bent.
That is another optical illusion.”
Rollo had often observed this phenomenor.
when he had been playing in the water, and
he told his father so; but he said that he
did not know before that it was an optical
illusion.
"What makes the stick look so crooked,
father?" asked Rollo.
"Why, it does not look crooked, exactly,'
replied his father. "It is only bent in one
place, and that is just at the surface of the
water. All that part of the stick which is


OPTICAL ILLUSIÓNS.
under the water looks straight, and all that
which is above the water looks straight; but
the two parts are not in the same straight
line with one another. The part which is
under water, seems to slope down more than
the other."
"Well, sir, and what makes it?" said
Nathan.
"You couldn't understand the explana-
tion, if I were to tell you.'
"Perhaps I could, father," said Nathan.
"I wish you would try."
"No," said his father; "you will have to
study mathematics, and geometry, and op-
tics, a long time before you can really un-
derstand that."
"Couldn't I understand it if you should
explain it to me?” said Rollo.
"No," said his father, "I think not."
"Well, father," said Nathan, “I wish you
would just tell me, and let me see if I can t
understand it."
The
"Well," said his father, "I will.
fact is, that the rays of light from the lower
part of the stick, in passing out from the
water, come from a denser medium to a
rarer, and are refracted, of course, from the
1
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THE SKY.
perpendicular. They are consequently de
pressed, and enter the eye at a smaller angle
with the surface of the water than they
would have done if their path had been all
the way through a uniform medium. This
changes the apparent position of every part of
the stick which is under water; as objects
appear always in the direction of the ray as it
enters the eye. That is the explanation; do
you understand it, Nathan?"
66 Why-no, sir," said Nathan, hesitating
"not exactly."
Rollo laughed.
"I thought you would explain it better
than that," said Nathan.
"I was not quite fair," said his father, "I
must acknowledge. I could have made it
not quite so unintelligible as that, though
that is the true explanation, and it would
be perfectly intelligible to any one who is
prepared to understand such subjects. But
it would not be wise for me to attempt to
explain the cause of that illusion to you now.
All I meant by speaking of it was, to let you
know what an optical illusion is. There
are a great many kinds of optical illusions."
"What are some of them?" asked Rolio
OPTICAL ILLUSIONS.
17
"Why, any thing which is off at a dis
tance looks very small. That is an ilusion
to young children, for they are often de-
ceived by it. Older persons learn to correct
the sight, and conceive of a person or a thing
which is a great way off as of the true size.
Thus, if Nathan were to see a boat coming
with men in it, a great way off upon the
water, he would think, perhaps, that the men
were boys; but an old sailor, accustomed
to see boats upon the water, would look
upon them as men. We do not generally
call it an illusion, unless it deceives us, or
partly deceives us.
66 So, when you are sailing down a river,
or along the shore of a pond, the trees on
the shore seem to move, and young children
always think at first that they are moving;
in fact, they can hardly believe that they are
not moving. It is an optical illusion."
"Well, father, what else?" said Rollo,
when his father paused.
"Why, the appearance of the sun, when
it first rises in the morning, is an optical
illusion. When we see the sun in the
morning, and it seems to be just above the
horizon, it really is just below. Its appear
!
2*
18
THE SKY.
ance above the horizon out of its real place,
is an optical illusion.
"Then the whole apparent motion of the
sun," continued Mr. Holiday, "is an optical
illusion. The sun does not move at all.
The sun does not go round the earth in a
day. The earth turns round on its axis be-
fore the sun; but the sun appears to move.
And this is an illusion which we never learn
to correct. We know that the sun stands
still, it is true; but we cannot make it
seem to stand still. After sailing up and
down a river, or around upon a pond for a
long time, we not only know that the banks
and the trees do not move, but they cease to
seem to move. But we never correct our
sight in respect to the sun and stars. They
continue to seem to us to move, all our lives.
We never succeed in making the earth seem
to move, and the sun and the stars to be
still. So that the apparent motion of the
sun and stars is a very obstinate optical
illusion."
"We.l, father," said Rollo, "tell us some
more optical illusions."
"The images in a looking-glass would he
considered optica. ilusions, if we were not

OPTICAL ILLUSIONS.
19
so accustomed to them that they tease to
deceive us at all. If a person who had
never seen a looking-glass, were to come
into a house and see one, he might imagine
that there was something behind it, and at-
tempt to take the glass away to look. You
might tell him, in such a case, that there was
nothing behind the glass; that the image
which he saw was an optical illusion."
"Well, father," said Rollo, "what was it
that you said, at first, about the sky being an
optical illusion ?”
"I said that the arched or dome-like ap-
pearance of the sky was an illusion.”
Here Rollo leaned his head again upon.
the top of the support which was at the back
of the seat that he was sitting upon, and
looked up into the sky. The clouds were not
so black and threatening as they had been,
but they extended, with some broken intervals,
all over the sky; and they seemed to form
one great swelling dome, as true and beauti-
ful as if it had been mathematically formed.
"Why, father," said he, "the clouds are
very high over my head, and all around they
come down nearer and nearer to the ground
and so they make a real dome."
20
THE SKY.
"No," said his father, "it is all an illu
sion."
"l
Why, father!" said Rollo.
"Yes," said he, "that great canopy of
clouds is flat."
"Flat? O father!" said Rollo.
"Yes," said his father. "I will explain it
、to you some day. But now we have got
home, and I must attend to setting out my
trees. I wish that you would go in and see
what time it is."
"No, sir; let me go," said Nathan.
"Why, you can't tell what time it is,"
said his father.
"Yes, sir, I can," said Nathan; "let me
try."
So Nathan clambered down out of the
wagon, when Jonas stopped in the yard, and
ran in, while Jonas, and his father, and Rollo,
began to take out the trees. Presently Na-
than came back.
"Well, Nathan," said his father, "what
time is it?"
"The long hand, -no, the short hand,"
said Nathan, speaking very deliberately, "is
at four ones, and the long hand at a one and
an X."

OPTICAL ILLUSIONS
23
QUESTIONS.
Describe the circumstances in which the conversation
recorded in this chapter occurred. What is the differenc、
between a dome and an arch? In what case is an arch
commonly built in houses? What example of a dome in
common houses? What did Mr. Holiday say of the dome-
like appearance of the sky? What is an optical illusion?
What optical illusion is observed by children in sailing?
What illusions are mentioned in the appearance of the
sun? What other optical illusions are mentioned? How
did Rollo argue to prove that the dome-like appearance
of the sky was not an optical illusion?
2.4
:
CHAPTER II.
THE PROOF.
AFTER tea, on the evening of the day when
Rollo and his father had had their ride in
the wagon after the trees, little Nathan came
into the parlor with a hoop in his hand.
His mother was sitting at the window,
sewing.
"Look, mother, look," said he, holding
up his hoop.
"Ah," said his mother, "a hoop. You've
got a hoop."
"Yes, mother," said Nathan; "it is mine
the whole of it. Jonas gave it to me.
He got it off a barrel."
"Did he?" said his mother.
"Yes; it is a beautiful hoop.
You may
drive it, mother, if you want to
time."
some
"May I?" said his mother; "weil, I am
very much obliged to you."
Nathan perceived that his mother did no

THE PROOF.
25
take any very great interest in his hoop after
all; and so he went out to find Rollo, to show
it to him. Rollo and his father were sitting
under the piazza, talking about the clouds,
and Nathan stopped to listen. The first
thing that he heard was Rollo's saying to his
father that the clouds were certainly very
high up from the ground directly overhead,
and that all around at a distance they came
down very near to the ground, and so they
made a real dome.
"No," replied his father; "they are as far
from the ground off at a distance as they are
here."
"O father!" said Rollo.
"Why, consider a moment," replied his
father. "Do you suppose that, when there
is such a canopy of clouds over the sky, if
you were to go into the next town, you
would find the clouds touch the ground?”
"Why, no, sir," said Rollo.
"Don't you suppose that you would find
them as high above the earth there, as they
are here?"
"Yes, sir," said Rollo, "I suppose they
must be; but they look as if they came down
to the ground."
3
26
THE SKY.
༔
"No doubt," replied his father. "They
ook so, I know. It is an optical illusion, as
I told you."
"O father," said Nathan, "I wish you
would show me the optical illusions in a
tumbler."
"Well," said his father, "go and ask
Jonas to give you a tumbler nearly full of
water, and I will. Can you bring it care-
fully?"
it."
Yes, sir," said Nathan. "I won't spill
And accordingly he went after his
tumbler.
While he was gone, his mother, who had
heard voices upon the piazza, concluded to
come out with her work, and join the party
there. So she took a seat by the side of
Rollo and his father, and began to listen to
the conversation.
When she heard Mr. Holiday say that the
arched appearance of the sky was an illusion,
she was much surprised.
"You see it must be so," said Mr. Holi-
day; "for, wherever we go, the clouds appear
high directly over our heads, and all around
at the sides they come down to the horizon.
But, if we were to go off to the next town,
THE PROOF.
27
10 the land which is now in our horizon,
no doubt we should find the clouds of the
same height there, over our heads, that they
are here.'
""
"Yes," said Rollo's mother; "but then the
earth is round, and I always supposed that
clouds conformed to the shape of the earth;
and so their being at an equal distance from
the earth every where, instead of making
them flat overhead, would make a dome."
"Yes," said Mr. Holiday, "that is true.
The earth is round, and the clouds conform
to its shape; but, then, for so small a distance
as we can see, this roundness is not percepti-
ble. The clouds do make a real dome over
our half of the earth; that is, they would if
so large a part of the earth was covered with
clouds at the same time. But such a dome as
that, would be as large as half the earth; that
is, it would be eight thousand miles across
it. But we do not see any such dome as
that when we look up at the clouds now.
We could not see such an expanse of clouds
as that at all, unless the earth were taken out
of the way, and we went and took our places
wre the centre of the earth now is. If we
were to do that, then we should see a real
.
1
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1
J
28
THE SKY.
:
dɔme of clouds, no doubt, eight thousand
miles across."
"It would be more than eight thousand
miles across, father," said Rollo; "for the
earth is eight thousand miles across, and the
great dome of clouds would be larger, for it
would be beyond the earth."
"Yes," said his father, "a very little,-
only three or four miles, however; and that
would not make any sensible difference in so
great a distance as eight thousand.
If you
were to draw a circle as large as you could
draw on a sheet of paper, for the earth, and
then attempt to draw another circle outside
of it, just as far off as it ought to be to repre-
sent the clouds three or four miles from the
earth, the outer line would be so near the in-
ner one, that there would hardly be room for
a hair to lie between them."
"O father!" said Rollo with surprise.
"Yes," said his father; "the clouds lie
very near the earth indeed, compared with
the agnitude of the whole globe; so that
you see it would be utterly impossible for us
to see the real arch or dome of clouds which
might be formed around half of the earth
from any place on the surface of it. Insteau
Y

THE PROOF.
29
of being eight thousand miles across, the
dome which we see is not often two or three
miles across; so that there is no doubt that
it is a mere optic illusion."
"Yes," said Rollo's mother, "it must be
so, I see; but I never thought of it before."
"Yes," rejoined Mr. Holiday. "If we
were in a great building with a flat ceiling
over our heads a mile high, and extending
several miles every way, there is no doubt
that it would look like a dome. And, in
fact, we can see the reason why it should."
"What is the reason?" asked Rollo.
"Why, every thing looks smaller to us the
farther off it is. And not only objects them-
selves look smaller, but the distance from
one object to another looks smaller. Now,
the distance of the ceiling from the ground off
half a mile from us, would look smaller than
the distance of the ceiling from the ground
very near us; and so the ceiling would
seem to come nearer and nearer to the ground
the farther off we look. And this would give
such a ceiling the appearance of a dome."
"Father," said Rollo, "why doesn't Na-
than come back with his tumbler?"
"I don't know," said his father
"Ha
3*
30
THE SKY.
has got engaged in playing somewhere, t
presume. But I want you to listen to one
more proof that the arched appearance of the
sky is an illusion; and that is a proof from
the stars. We might suppose the clouds to
be spread evenly over our heads, and to be
slightly arched, corresponding with the earth.
But in regard to the stars, there is nothing
of the kind. The sun, moon, and stars, are
scattered irregularly in space, some nearer,
and others very remote. There is nothing
like an arch or curve of any kind about them.
And yet, when we look up in the evening,
they are all brought into the same surface,
and that surface takes the form of a beautiful
dome. It must of course be entirely an illu-
sion in that case."
"Father," said Rollo, "how high are the
stars?"
"O, they are too far off," said his father,
"for you to have any conception of the dis-
tance, if I were to tell you."
"L
Well, how high are the clouds, then?'
asked Rollo. "You can tell me that."
"They are of very different heights," said
his father. "Some clouds touch the earth
and some are several miles high."
THE PROOF.
31
"Do some clouds touch the arth? 1
never saw one."
"Yes," said his father. "You have seen
mists and fogs, and they seem to be only
clouds lying upon the earth."
66
"I did not know that," said Rollo. '1
thought fogs and mists were very different
from clouds."
"No," said his father; "they are the same."
"How do you know, father?" said Rollo.
"The philosophers have ascertained in
various ways," replied his father. "Clouds
sometimes lie against the sides of the moun-
tains, and, as we know how high the moun-
tains are, we know how high the clouds are.
I believe they have a way, too, of finding out
how high a cloud is by the shadow it casts."
"How do they do it?" asked Rollo.
"I don't know," replied his father, "how
it is done; but I believe they have a way."
"I shouldn't think they could find out
any thing by the shadow."
"Yes," said his father; "you know you
can measure how high the steeple of a church
is by its shadow, or a house, or a tree."
"No, father," replied Rollo; "because
sometimes the shadows are very long, and
32
THE SKY.“
!
•
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2
sometimes they are very shc t; and so we
can't tell any thing by the shadow."
"Yes," rejoined his father. "Suppose you
put a stake into the ground so long that it is
Just one foot above the ground. Then in
the morning you look at the shadow. Yqu
know it will be very long."
"Yes, sir," said Rollo.
"Because," continued his father, "the sun
has not risen very high, and so the rays shoot
away beyond the stick, and make the shadow
extend a long way on the ground.”
'Yes, sir," said Rollo.
"Now, if you wait a little while, till the
sun rises higher, and then look at the shadow
again, will it be longer or shorter ? "
"6
Shorter, sir," replied Rollo.
"Right," replied his father.
"Now, you
can watch it until you find that the shadow
is just as long as the stick itself. And then,
when the shadow of a stick one foot high
is just as long as the stick, the shadows of
every thing will be just as long as the objects
that make them. Then you have only to
go and measure the shadow of a tree, and
that will tell you how high the tree itself is
And so with a house, or a steeple, or any
THE PROOF.
33
other thing so tall that you cannot get at the
top of it to measure it."
"Yes, father, I understand; and I think
it is an excellent way."
"I think it is a very good way indeed,"
said Rollo's mother.
"I mean to measure how high our house
is, to-morrow," said Rollo. "I'll get Jonas
to help me."
"It is not necessary," continued his father,
"to wait until the shadow is as long as the
stake. If it is twice as long, it will do just
as well, because then you would only have
to measure the shadow of the house, if it
was a house that you were going to measure,
and then take half the length of the shadow,
and that would be the height of the house.
For if half the shadow of the stake was as
long as the stake itself, half the shadow of
he house would be the height of the house
itself; for all shadows made by the sun at
the same time, are in the same proportion."
"Yes, sir," said Rollo; "though that
would not be quite so easy."
"No," replied his father, "it would not
be quite so easy; but it might save you some
time, in waiting for the shadow to get just
34
THE SKY.*
E
equal. And so, if the shadow was too snoit,
-for instance, if it was only half as long as
the stake, then the shadow of the house
would be half the height of the house. In
that case, you would have to measure the
shadow of the house, and then double it."
"Yes, sir," said Rollo.
م
"And if you were a mathematician," con-
tinued his father, "it would be of no conse-
quence how long the shadow was in reference
to the stake, because you could calculate.
You could write down the length of the
shadow of the stake, and the length of the
stake itself, and also the length of the shadow
of the house, and so make a calculation.
But as you are not a mathematician, it
would be better, if you undertake to measure
in this way, for you to wait until the shadow
is just equal to the height of the object, or
half as long, or twice as long; for then you
could calculate easily."
"Well, sir," said Rollo, "I'll wait till it's
just equal, and then I shall be sure.
"And now I wish Nathan would come
back. I don't see what has become of him,
I mean to go and find him."
Rollo accordingly left his father and meth

THE PROOF.
35
er and went in pursuit of Nathan. He found
hi in the kitchen, standing at a table with
a tumbler of water before him, which he
seemed just ready to take up and bring
along, only he was talking to Dorothy.
"There isn't, Dorothy," said Nathan, in a
very positive tone.
"There isn't what?" said Dorothy, whe
was busy with her work, and was not pay-
ing any particular attention to what Nathan
was saying.
"There isn't any sky.'
"Isn't there?" said Dorothy.
"No," replied Nathan. "There isn't any
sky at all. There are some clouds, and
some stars; but," continued he, shaking his
head very seriously, "there isn't any sky."
(C
'Ah," said Dorothy.
"No," said Nathan, "nor any dome.
all a
""
It's
Here Nathan hesitated, not
being able to recollect the word.
"All a what?" asked Dorothy.
"I don't remember what the word is,"
said Nathan. "It is something which father
is going to show me in this tumbler. I
don't remember what the word is, but I
know what it means."
""
36
THE SKY.
{
"What does it mean?" asked Dorothy
"It is something that means mistake."
"Come, Nathan," said Rollo; "we are a
vaiting for you."
"Yes," said Nathan, "I'm coming
QUESTIONS.
What illusion was it that Mr. Holiday was going te
show the children by means of the tumbler of water? How
did he show that the dome-like appearance of the sky was
an illusion? Did he maintain that the canopy of clouds
was perfectly flat? What did he say about the height of
the stars? What about the height of the clouds? How
did he say that the height of the clouds had been ascer
tained? Explain the process by which he first proposed to
Nathan to measure the height of a steeple by its shadow.
Was it absolutely necessary to wait untii the shadows were
equal to the objects which cast them? Did Rollo conclude
to try the experiment? What did he say that he intended
to attempt to measure ?


37
CHAPTER III.
APPARENT MAGNITUDE.
ONE summer afternoon, Miss Mary, who
for a time taught a school where Rollo used
to go, as is described particularly in the book
entitled "Rollo at School," invited Rollo and
his cousins Lucy and James to come and
take tea with her. They all went. In the
evening, after tea, they were going out to
take a walk. Miss Mary was not quite
ready. Lucy and James were sitting at the
table, looking at some picture-books which
Miss Mary had given them to amuse them-
selves with while they were waiting for her.
Rollo was looking out at the window, and
all at once the attention of Lucy and James
was taken off from their books by hearing
Rollo call out,
“O, come and see this great fire!"
They all went to the window. There
was, indeed, what appeared to be a great
blazing fire, away across a valley which they
D
4
38
THE SKY.
looked upon from the windows of the house.
There were two large trees, and the fire
appeared to be between the trees. Rollo
thought that it was a house on fire, and that
the two trees were before the house. The
fire filled up the whole space between the
trees.
"It must be a house," said Rollo, "and a
very large house too."
"I guess it is a meeting-house," said
James.
"I guess it is the moon," said Miss Mary.
"The moon!" repeated Rollo. "It is a
great deal too large for the moon. The
moon is not as big as that.'
""
"How big is the moon?" said Miss Mary.
"Why yes," said Rollo, "I know
--
the moon is actually as big as a house; but I
mean it does not look as big as that."
"How big does the moon look?" said
Miss Mary.
Why, about as big as a large plate," said
Rollo.
"O Rollo," said James, "it looks bigger
han a plate. It looks as big as a cart
wheel."
"It looks about as big as the top of a hat
JJ

APPARENT MAGNITUDE.
34
to me," said Lucy. "It looks different to
different persons, I've heard people say."
"That is a mistake," said Miss Mary
"It looks about the same to all people."
"But, Miss Mary," said Lucy, "Rollo
says it looks as big as a plate to him, and
James says it looks as big as a cart wheel to
him. I should think they would know."
66
"L
"They do know," said Miss Mary.
Why, one or the other of them must be
mistaken," said Lucy, "if it really looks the
same to them both."
"No," said Miss Mary, "I don't think
that either of them is mistaken."
66
Why, Miss Mary," said Lucy, "how
can that be?"
"It seems strange," replied Miss Mary, "I
know; but so it is. I have no doubt that
the moon looks as big as a cart wheel to
James, and as big as a plate to Rollo, and
yet it looks just as big to one as it does to
the other."
"O Miss Mary," said James, "a cart
wheel is a great deal bigger than a plate."
"Yes," said Miss Mary, "and yet what I
say is true, and I presume I can prove it to
your satisfaction."
40
THE SKY.
"You've got a pretty hard thing to prove
Miss Mary," said Rollo, "I think.'
""
"I am not certain that I can prove it to
your satisfaction; but I am certain that it is
true, at any rate.'
""
By the time that this conversation was
concluded, there was no longer any doubt
that the great light which the children had
seen was really the moon; for it had risen a
little, and its round form could be seen,
large and full.
"What a large moon!" said Rollo.
"How large does it appear to you to be
now?" said Miss Mary; "as large as a car?
wheel?"
;
"No," said Rollo; "but it looks larger
than usual. It looks as large as a very large
plate indeed."
"But you said, a few minutes ago, that it
looked as large as a house."
"Well, it did then," replied Rollo; "but it
has got up higher now, and I can see it better."
"Don't you see that it just fills the space
between two trees?" said Miss Mary.
The moon had in fact risen a little, but it
was still between the two trees, and it was
just large enough to occupy the space be

“WHAT A LARGE MOON," SAID ROLLO.-Page 40.
NIL
M
OF
C
*
*
*
•

APPARENT MAGNITUDE
41
tween them, just as it had done when it
began first to peep up above the horizon.
"Yes," said Rollo, "it does."
“And did it more than fill the space be
tween the trees when it was lower down
and you thought it was a house on fire?'
asked Miss Mary.
(6
No," said Rollo.
“Then doesn't it look just as big now as
it did then?"
No," said Rollo ;
"it looked as big as a
""
house then, and it does not now. It does
not, certainly, Miss Mary.
“But consider a moment, Rollo. Suppose
you could reach your hand out, and move
the moon back down to the horizon again,
and keep it between the two trees; don't you
see that you wouldn't change the size of it.
The trees are just as far apart at the bottom
as they are higher up."
"Yes," said Rollo; "I didn't think of
that."
"So that, although it looked as big as a
house before, and only as big as a plate now,
yet, after all, it looks just as big now as it
did then."
"I don't see how that can be," said Rollo.
4*
42
THE SKY.
Miss Mary.
"But yet you see that it must be," said
"For the measure of the
breadth of the moon now, is the distance
between the two trees; and the measure
when it was first rising was the same; and·
of course, its apparent size cannot have
altered."
Rollo was puzzled. In fact, all the chil-
dren were puzzled too. They saw that
Miss Mary's arguments were entirely unan-
swerable; but yet they could not under-
stand how a thing could look as big as a
house, and then afterwards only look as
big as a plate, without appearing to grow
smaller.
"Now, children," said Miss Mary, "I will
try to prove to you that the moon does not
look bigger than a wafer.'
19
"O Miss Mary!" exclaimed the children.
Miss Mary said nothing to their exclama-
tions, but she opened a little drawer in a
table which stood in a corner of the room,
and took out a pencil and a paper. She
gave them to Lucy, and asked her to put the
paper up to the window in such a place that
she should se、 the moon by the ride of the
edge of the paper.
APPARENT MAGNITUDE.
43
"There," said she, "I want you to draw a
itle circle on the paper, just as large as the
moon. By having the moon right by the
side of the paper, so that you can compare
your drawing with it, you can see. And
you, James and Rollo, must not see her do it.
You must go to another part of the room,
and, when Lucy has finished her drawing,
you shall try too."
So Rollo and James went to the table, and
began to look at the picture-books, standing
with their backs to Lucy, in order that they
might not see how big she made her moon.
Presently Lucy told Miss Mary that she had
made it.
"Very well," said Miss Mary. "Now,
hold up your paper upon the glass again, and
bring your drawing and the moon as close
together as you can, and compare one with
the other, and see which looks the biggest.
Perhaps you can slip your drawing directly
over the moon, and see whether it is big
enough to cover it exactly or not."
Lucy was very busy for a moment or two
comparing her circle with the circumference
of the moon, and then she said that hers was
a little too big.
44
THE SKY.
"Then make another, a little smaller," said
Miss Mary.
Lucy made another, and brought it to Miss
Mary. She put it in the drawer without
etting the other children see it. Then she
gave Rollo a piece of paper, and let him make
a drawing of the size of the moon, as it ap-
peared to him; and lastly James tried.
When the drawings were all ready, she
placed them upon the table side by side, and
let the children look at them all together.
"There," said Miss Mary, "there are your
representations of the apparent size of the
moon, and there is not one of them that is as
big as a wafer!"
The children did not know what to say in
reply to this reasoning.
"The explanation of the mystery is this,"
said Miss Mary. "Things appear of very
different size, according to the distance they
are from us. A ship, for instance, when it is
hear, appears very large; but, when it is.
away off in the horizon, it looks like a mere
speck. So a cart wheel looks large near us,
but at a distance, it looks very small."
Why, now, Miss Mary," said Lucy, “I
think a cart wheel always looks of the same.
size."

APPARENT MAGNITUDE.
45
"No," said Miss Mary, "you are deceive‹
in that. It is true that, when you see a cart
wheel at a distance, you know what it is, and
so you know about how big it must be; but
in its mere appearance it is small. When we
look out of the window, a wafer on the glass
would fill the eye as much as a large house
away off on the hills.
"So when James," continued Miss Mary,
"says that the moon looks to him as big as
a cart wheel, he does not mean a cart wheel
close to his eye. If we were to put a cart
wheel up to the window where you put the
papers to make your drawings, it would be
big enough to cover twenty moons. And
then, again, if the cart wheel was a mile off,
hoisted up into a tree where we could see it,
and the moon were to rise near it, we should
see that the moon would then appear much
larger than the wheel.
"Thus," continued Miss Mary, "you see
that, when any body says how large the moon
appears to be to him, it all depends upon
how far off he imagines the thing to be tha'
he compares with the moon.
And the way
that I took to make the moon appear smaller
han a wafer to you was, to make you draw
46
THE SKY.
a representation of it on paper which you
had to hold pretty near your eye. If I coula
have hung up a monstrous great sheet of pa-
per, away off by those two trees, and you
had arms long enough to reach there, you
would have had to make your drawing of
the moon as large as the whole space between
the trees. ""
"O Miss Mary!" said Rollo.
"Certainly," replied Miss Mary; "for you
remember that the moon itself filled up that
whole space, and of course, if the drawing
was made to look as large, that would have
to fill it up too.
"And now," continued Miss Mary, "I
want you to remember this general principle,
which we learn from all these things,
namely, that apparent distances, and the ap-
parent magnitude of objects in the sky, can-
not be measured by comparing them with
distances and objects about us on the earth.
If any body were to say that the moon ap-
peared to be a foot across, or a yard, or a mile
across, he would not give any definite infor-
mation at all. And it would be the same if
he should say that the distance from one star
to another, as it appears in the sky, is a mile,

APPARENT MAGNITUDE.
47
or a rod, or four yards. They have a very
different way of measuring distances and di-
mensions in the sky."
"How do they do it?" asked Lucy.
"I will tell you presently, when we go out
to take our walk. I am almost ready."
Miss Mary then took up the books which
the children had been looking at upon the
table, and put them away. She also was
going to put away the drawings which the
children had made of the size of the moon;
but Lucy wanted hers, she said, to carry home
and show to her mother. James and Rollo
then wanted to take theirs too. In a few
minutes after this, the room was all arranged,
and the children went out with Miss Mary to
take a walk.
QUESTIONS,
Where were the children when the conversation took
place, which is described in this chapter? Who were the
persons engaged in it? What incident introduced the
conversation on the apparent size of the moon? How
large did Lucy say that the moon appeared to her?
did Rollo say? ames? What was it that Miss Mary
Wha
48
THE SKY.
串
​*
raid on the subject, which perplexed the children very
much? How did she prove that the moon did not appear
bigger than a wafer to them? What circumstance does
the apparent magnitude of any object depend chiefly upon
Can we, then, estimate magnitudes and distances in the
skies by comparing them with obiects on the earth?

49
CHAPTER IV
DEGREES.
NEAR the house where Miss Mary lived
was a little hill with a path through the trees.
leading to the summit. Miss Mary said that
they would go up to the top of that hill, for
there they could see the stars and the sky
better; and she said that she was going to
tell them something about the stars and
the sky.
The view by the moonlight from the top
of this hill was very beautiful. One side of
the landscape at a distance was pretty level,
and the sky came down and met the ground
in a smooth line. On the other side there
were some mountains, and the moon tipped
their summits with a silvery light. There
were a number of floating clouds in the
sky; and the moon was sometimes wading
through them, and sometimes it shone out
clear. There were not a great many stars.
"Now," said Miss Mary, "I am going to
5
ან
THE SKY.
explain to you how they measure and de-
note distances in the sky; and you must
attend as carefully as if you were listening
to a lecture.
"The first thing to explain to you," said
Miss Mary, "is the horizon. Do you know
what the horizon is?'
""
"Yes," said Lucy; "the line where the
sky and the land meet."
"That is commonly called the horizon,'
said Miss Mary, "but that is not it exactly.
For instance, look out that way where the
mountains are. Does the horizon run along
on the tops of the mountains?
""
“No,” said Lucy, "I suppose not. I sup-
pose the horizon is where the land would
meet the sky if the mountains were taken
away."
"That is right,' said Miss Mary. "The
horizon is the line where the land would
meet the sky if the land was perfectly level.
We can see the exact horizon when we look
off upon the sea; but we never can see it
upon the land, because the land is never
precisely level.
"However," continued Miss Mary, "the
ine where the sky and land meet is pretty

DEGREES.
51
near the horizon, and it will answer to rep-
resent the horizon. Look at the horizon all
around; it is a great circle. If we begin
here," said Miss Mary, pointing out to the
horizon before her, "and then move round
and follow it," and so saying, Miss Mary
turned slowly, keeping her hand extended
towards the horizon, 66 we shall come round
through the whole circle, and back to the
place where we began. So the horizon is a
circle.
"6 Now, let me ask you one question," con-
tinued Miss Mary, "to see whether you un-
derstand what I have been saying. Suppose
we could see a star just peeping over the
tops of the mountains, out that way, would
it be above the horizon, or below the horizon,
or in the horizon?"
"Above the horizon," said all the children
"That is right," said Miss Mary.
"Now, look up in the sky, and find the
point that is exactly over your head."
The children all immediately began to
look up.
"It's right there," said James, pointing up
"there, by that bright star."
52
THE SKY.
·
i
"Is that exactly in the centre?" asked
Miss Mary.
..
"No, not exactly," said Lucy. The
centre is a little farther that way." So say-
ing, Lucy gestured with her hand to show
which way she meant.
""
"That is the zenith," said Miss Mary.
"The point in the sky that is exactly over
our heads in the centre, is called the zenith.'
"I can't see the zenith," said James.
"O dear me!" said Rollo, "how it makes
my neck ache to look at the zenith!"
The children all found that holding their
neads back in such a position was painful,
and so they desisted.
"I know you cannot see it," said Miss
Mary, in answer to James; "there is nothing
there that you can see."
"Then how do you know that there is
any zenith?" said he.
"Why, suppose we were in the house,
and I were to ask you to take a pin and
stick it down through the carpet into the
floor exactly in the middle of the room, and
you were to go and try to find where the
mid lle of the room was; should you expect

DEGREES.
53
to see any mark or sign by which you would
know the middle of the room?"
"No," said James.
"And suppose Rollo should say there was
not any middle to the room, because you
could not see it, what should you tell him?";
"Why, there must be a middle some-
where," replied James, "even if I could not
find it exactly."
"What is the middle?" asked Miss Mary,
"Why, it is it is just half way from one
side to the other."
"Yes," said Miss Mary; "it is nothing
that you can see. It is only an imaginary
point, which you have to find by instru-
ments.'
""
"Yes," said James.
"It is just so with the zenith. There is
no mark in the sky at the place; but there
must be a point there, somewhere, which is
exactly over our heads, though we cannot
see it. By looking up, we can see pretty
nearly where it is; but we cannot find it pre-
cisely without instruments."
"Wha: kird of instruments?" asked
Lucy.
"I do not know," said Miss Mary; "but I
¿
5*
54
THE SKY.
!
J
L
2.
}
know that the astronomers have some kind
of instruments by which they find the zenith
when they wish.
"We cannot see precisely where either
the horizon or the zenith is," she continued,
"though we may know what they are; and
we can see pretty nearly where they are.
"The whole horizon," continued Miss
Mary, "is a circle; and half of the horizon
is half a circle. That is, if we begin at any
place in the horizon, and go round till we
come to the point exactly opposite to it, we
go over half a circle. Do you see that little
light out that way?" said Miss Mary,
pointing.
"Yes," said Lucy; "it is a star just com-
ing up.
""
"Perhaps so," replied Miss Mary, "o
perhaps it is a light burning in a house;
never mind which; for it will do, in either
case, to mark a place in the horizon. Now,
let us look opposite to it on the other side of
the horizon, and see if we can find any thing
for a mark there.”
The children all turned and looked. The
mountains were on the side of the horizon
opposite to the light. They selected one
:

DEGRE ES
55
which was higher than the rest, and which
seemed nore exactly opposite to the light
than the rest.
"Now," continued Miss Mary, "if we
begin at the star, and pass round in the hori-
zon,”—and so saying, Miss Mary pointed to
the star, and then moved slowly around, car-
rying her finger along the line of the horizon.
"until we come to the mountain, we
shall have gone over just half of a circle.
Do you understand that?
The children said that they did. In fact,
they thought that it was very easy to under-
stand.
"Now," continued Miss Mary, "if we be-
gin at the star, and, instead of going round in
the horizon, go over through the zenith, and
so down on the other side to the mountain,
that will be just half a circle too; because
the dome of the sky is shaped like just half
of a ball, and so it will be half of a circle
from any place in one side, over through the
top, down to the other side.
"Now answer me some questions," said
Miss Mary. "How large a part of a circle
will it be, from the light up through the
56
THE SKY.
zenith, and down on the other side to the
mountain ?"
"Half a circle," said all the children.
"And how large a part of a circle will it
be from the light up to the zenith?"
"Quarter of a circle," replied Lucy.
"Yes," said Miss Mary; "and how much
from the zenith down to the mountain ?"
"Quarter of a circle," said all the children.
"And so from the zenith down to the ho-
rizon, at any place, will be a quarter of a cir-
cle," said Miss Mary. "Now, they divide
such a quarter of a circle into ninety parts,
which they call degrees; and they measure
objects and distances in the heavens by the
degrees."
"How much is one degree?" asked Lucy.
"About twice as much as the breadth of
the sun," replied Miss Mary. "For the disk
of the sun is about half a degree in diameter.
If the sun were to come so much neares to
the earth as to look twice as large every way,
then the breadth of the sun would be a de-
gree."
"And the moon," said Lucy, looking out
at the same time towards the moon, "how
broad is the moon?"

DEGREES.
bi
"It is just about as big as the sun," said
James.
"Yes," said Miss Mary; "so that the di-
aineter of the moon is about half a degree.
In reality, he moon is a great deal smaller
than the sun; but then it is so much nearer,
that it occupies just about the same place in
the heavens. If there was a great balloon, as
big as a house, rising up before us, and very
near, it would perhaps be eight or ten de-
grees in apparent magnitude. But as it went
off to a greater distance, it would grow small-
er, until it filled only a space of half a degree
in the sky, when it would look about as large
as the sun. If it went off farther still, it
would look smaller and smaller, until it was
only a quarter of a degree in diameter. At
last, it would be just ready to vanish, and
then its diameter might perhaps be only a
minute."
"A minute?" said Lucy.
"Yes; a minute is only a very small part
of the circle of the sky."
"How small?" asked Lucy.
"O, very small indeed," said Miss Mary.
"It takes sixty minutes to make a degree.
+
58
THE SKY.
How many minutes would there be in the
diameter of the sun?"
The children did not answer.
"Why, you remember that I told you that
the diameter of the sun is about half a degree,
and, as a degree is sixty minutes, the diame-
ter of the sun would be thirty."
"And the moon too," said Rollo.
"Yes," replied Miss Mary, "the moon is
the same.
So that if you can imagine how
much one thirtieth part of the diameter of the
moon is, you will know how much a min-
ute is."
"I should think a bright star was about a
minute," said Lucy.
"Yes," said Miss Mary; "perhaps the ap-
pearance of a large bright star comes nearer to
it than any thing else we can compare it to;
or one of the horns of the moon, near the
tip, when the moon is new. Though a
minute is too small to be seen very distinctly
by the eye. They measure it with very nice
instruments. Can you remember how many
degrees it is from the zenith down to the ho
rizon?
""
"Ninety," said Lucy.

DEGREES.
59
"Yes," said Miss Mary. "Now, Lucy
point up to the zenith."
Lucy did so.
"And, Rollo, you may point to the ligh
in the horizon.'
So Rollo pointed to the light. Thus they
stood, James with his arm extended upward,
and his finger directed towards the point in
the sky which was directly over his head,
and Rollo with his arm extended horizontal-
ly, and his finger towards the light.
Now, Lucy," said Miss Mary, "I want
you to point to the place in the sky which
is exactly half way between the light in the
horizon and the zenith."
Lucy did so.
and then at the
She looked first at the light,
horizon, and, measuring the
distance with her eye, she divided it as
nearly as possible, and then pointed to the
middle.
"Now, from the light to the zenith is
ninety degrees," said Miss Mary; "and of
course from the light to the place where
Lucy is pointing is half of ninety degrees.
Half of ninety is forty-five; and, of course,
Lucy is pointing to the place in the sky
which is forty-five degrees above the horizon.
bl
THE SKY.
It is also forty-five degrees below the zenith.
Now, I want you to notice how grea, the
space is, so that you will know how much
forty-five degrees is."
The children looked at the place where
Lucy was pointing, and then from that place
down to the horizon, so as to see how much
forty-five degrees was. Then Miss Mary
told them that they might all put down their
hands.
(6
Now," said Miss Mary, "look all over
the sky, and see if you can find a cloud which
extends over as much as forty-five degrees of
the sky."
The children all looked, but they said that
there was no cloud large enough. There
were a few small white clouds floating near
the moon, but they were all much less than
forty-five degrees in extent.
"There is a cloud which the moon is just
going into," said Miss Mary.
"How large
is that cloud?"
The children hesitated. They did not
now exactly how to go to work to esti-
inate it.
"You can tell by comparing it with tid
moon."

DEGREES.
61
It is about twice as wide as the moon,"
aid Lucy.
"Then how wide is it in degrees?" asked
Miss Mary.
"Why, one degree," said Lucy, "if the
moon is half a degree."
Yes," said Miss Mary; "s that that
cloud shows you very nearly how much
one degree is. Now, how many degrees long
is it?"
Lucy thought it was three degrees long,
and James and Rollo, two degrees. Miss
Mary said that perhaps it was between two
and three. "And now, children," she con-
tinued, "you have studied enough for one
lesson, only there is one thing that you must
understand and remember; and that is, that
a degree is not any particular length in feet
or yards; it is only the apparent space in
the heavens which the object occupies.
The number of feet or yards included in a
degree depends altogether upon how far off
the thing is. A palloon a mile from us
might be half a degree in diameter, and so
be as large in degrees as the sun, which is a
million of times as big as the balloon; so
that half a degree on a balloon a mile from
{
6
62
THE SKY.
us, would not be more than forty or fifty
feet; but at the distance of the sun, it would
include many thousand miles."
Miss Mary and the children then went
lown the hill, and returned to the house.
On their way, Rollo told Miss Mary what his
father had told him about the dome-like ap-
pearance of the sky being an optical illusion.
"Yes," said Miss Mary, "it is, I have nc
doubt."
"And he told us about several other op-
tical illusions," said Rollo.
Lucy asked what they were, and so Rollo
told her. Miss Mary said that they were
very remarkable, but that she knew one
optical illusion which was a little more re-
markable. she thought, than all those.
"What is it?" said Lucy.
"The rainbow," said Miss Mary.
"The rainbow!" exclaimed the children
"Is the rainbow an optical illusion?”
.66
Yes," replied Miss Mary, "I believe
is. I believe there is no rainbow except in
people's eyes."
"O Miss Mary!" exclaimed the children
"And no two persons see a rainbow in
the same place," said Miss Mary.

DEGREES.
63
The children were very much surprised
at these statements, and thought that Miss
Mary must be mistaken. She said, however,
that she could not explain it to them then,
but that, if they would come and see her
some other day, she would tell them about
the rainbow. 66 'And, in the mean time,”
said she, "whenever you see any thing in
the sky, try to estimate its magnitude in de-
grees, and that will fix in your minds what
I have told you."
QUESTIONS.
Where did the children go, when they went out to hei
walk? What is the horizon? Could the children actually
see the horizon? What is the name of the point exactly
overhead? Could the children find the zenith exactly?
How large a part of a circle is it from the zenith down to
the horizon? How many degrees are there in a quarter cr
a circle? Is the apparent breadth of the sun more or less
than a degree? What did Miss Mary say about a balloon ›
What did Miss Mary mention, at last, as a most remarkable
optical illusion ?
.
•
64
CHAPTER V.
CLOUDS.
THE children thought no more of Miss
Mary's promise to explain what she had said
about the rainbow, for some weeks after
this. Perhaps they never
they never would have
thought of it again, if it had not happened
that they had an opportunity to see a rain-
bow, one afternoon, in company with Miss
Mary, under somewhat extraordinary circum-
stances. The occurrence was as follows:
One afternoon, when Lucy had come to
spend the day with Rollo, Rollo's father said
that Jonas might take Rollo, Lucy, and Na-
than, to ride in the carryall. They were
very much pleased with the plan. They
did not wait to have the carryall brought to
the door, but they went out to the yard in
front of the carryall-house, and got into it
while Jonas was harnessing the horse.
Rollo took his place on the front seat, say-
ing that he meant to ask Jonas to let him

CLOUDS.
65
drive part of the way. Lucy he ped Nathan
in behind, and then she got in herself.
When they had got in, they found that they
did not occupy nearly all of the space upon
the back seat. Nathan was quite small, and
Lucy was not very large, so that they both
together did not need much more than half
of the seat. Lucy therefore told Rollo that
there was room for somebody else to go, and,
after some discussion on the subject, they
concluded to stop at the front door, and ask
their father to let them go and invite Miss
Mary to take a ride with them..
Rollo's father consented very readily, es-
pecially after he had looked into the carryall
and saw how much room was left on the
back seat, when Lucy and Nathan sat close
together. When they arrived at Miss Ma-
ry's house, and gave her the invitation, she
seemed very much pleased, and she said
that she would be ready in a very few min-
utes. So they waited at the door until she
was ready, and then the whole party drove
away.
They had a very pleasant ride, and they
spent half an hour in climbing about some
rocks on the Suady side of a hill, gathering
6 *
56
THE SKY.
.
flowers. There was a little spring which
came out of a chasm in the rocks about half
way up the hill, and here Miss Mary and the
children sat down to eat their luncheon
Generally, on such expeditions, the children
took something to eat, and a little dipper to
dip up water with from the brooks and
springs, to drink. After their luncheon, they
clambered down the rocks, and got into the
carryall again to go home.
They undertook to go home by a new
way, which led through an unfrequented part
of the country. It was upon a road which
was not much travelled, and for nearly two
miles there was no house. Just before they
entered upon this unfrequented part of the
road, they saw in the western part of the sky,
which was directly before them, some large
and rounded clouds. The clouds were in
full view, for they were riding towards the
west.
"Jonas," said Rollo, "there is going to be
a thunder shower."
"I think it very probable," said Jonas.
"Those clouds look like a thuder shower."
"Yes," said Rolo, "only I don't hear
any thunder.

CLOUDS.
67
"The clouds don't rise very fast," said
Rollo.
"No," said Jonas; "I suppose they don't
rise at all."
"Yes, Jonas," said Rollo; "they are high-
er than they were a little while ago, and
presently they will be away up in the sky."
"How many degrees high are the tops of
them now?" said Miss Mary.
"Let me see," said Lucy; and she looked
earnestly forward over Rollo's shoulder.
Lucy judged that the highest tops of the
clouds were about a quarter part of the way
from the horizon to the zenith.
"That," said she, "would be a quarter of
ninety degrees. How much is a quarter of
ninety, Miss Mary?'
""
"Cannot you calculate it?" said Miss
Mary.
"Why, a quarter of eighty would be
twenty," said Lucy; "and I don't think the
clouds are quite a quarter of the way up,
and so we'll call them twenty degrees high."
"Yes," said Miss Mary, "I should think
that they were about twenty degrees high.
When they are half way up the sky, they
will be forty-five degrees high. I suppose
+
68
THE SKY.
2.
C..
there will not be much danger of rain until
they are more than forty-five degrees high."
"But, Jonas," aid Rollo, "you said that
they are not rising at all.”
"I thought they were not," said Jonas,
"but Miss Mary knows best.”
"But what made you think they were not
rising at all?” asked Rollo.
"Why, your father told us," said Jonas,
"that the surface of the clouds was not really
arched, but flat and level, and that the ap-
pearance of the dome was an illusion. Now,
if that is so, then the clouds that appear to
be rising in the west, must be really not ris-
ing, but only moving along towards us on a
flat."
"Yes," said Miss Mary, "that is right.
The clouds are, indeed, only moving along
towards us on a level, or at least on what is
very nearly a level. Their rising is only ap-
parent. Of course, when any thing is moving
along towards us, since it grows larger and
larger in appearance as it approaches, the top
of it must appear to rise."
"Then the clouds are not really rising?"
"No," said Miss Mary, "only approach
ing."
CLOUDS.
69
"Then," said Lucy, "what do you mean
by saying that now they are twenty degrees
high, and presently they will be forty-five
degrees high?”
Why, I mean that now they appear to be
twenty degrees high, and that by and by
they will appear to be forty-five degrees
high."
"But I don't see what good it does to
know that."
"Why, that is the nature of degrees," said
Miss Mary.
"Degrees and minutes are the
measures of appearances, not of realities."
"I did not know that," said Lucy.
·
"Yes," said Miss Mary. "The sun and
the moon, measured in degrees, are equal;
that is, they are both about half a degree in
diameter. But measured in reality, the sun
is a great many hundred thousand times the
largest. So that the half degree only meas-
ures the appearance.
"But remember," continued Miss Mary,
"I do not say that degrees never measure
any thing but appearances. Sometimes they
are employed to measure realities; but when
they are employed to measure distances and
magnitudes in the sky, it is apparent dis
70
THE SKY.
tances and magnitudes that they measure.
So, when we use degrees to measure the rising
of the clouds, it is only the apparent ising
that we measure."
"There, Jonas," said Rollo, "here comes
the last house."
Rollo pointed to a small house before them
down the valley. It was the last house be-
fore they came upon the two miles, which
were without any habitation.
"Yes," said Jonas, "and if I thought that
we should not have time to get through the
two miles before the shower, it would be
best to stop here; for the wind will blow
the rain directly into the carryall."
"Well, Jonas," said Miss Mary, "do you
hink that we can get through? "
"Yes, I think so," said Jonas; "the clouas
rise very slowly."
Clouds always appear to rise very slowly
at first, because, although they may be really
advancing with great speed, their motion
does not produce so great an effect upon
their apparent elevation, as the same progress
would when they were nearer. While the
conversation above described had been taking
place, the clouds had come on towards the
CLOUDS.
7.
children many miles; and, besides, the party
in the carryall were going rapidly towards
the clouds. But still the clouds were so far
off that no great effect was yet produced
upon their apparent elevation. Lucy thought
that now the upper edge of the clouds might,
perhaps, be thirty degrees above the horizon,
"I think we shall have time to get home,"
said Jonas. "You had better give me the
reins, now, Rollo, and let me drive, for I can
drive faster."
Jonas's estimate of the distance which
they had to go, compared with the time
which would probably elapse before the
shower would come on, was very correct;
and the party would doubtless have had
time to reach home before the shower, had
not an unexpected cause of delay intervened.
After passing the house which Rollo had
referred to, they ascended a hill, and then,
turning round a corner, they entered a wood,
and drove on nearly a mile, when they saw
a large, loaded wagon in the road before them,
which seemed to be tipped down upon one
side, as if it was in some difficulty. There
was a man apparently at work about it, bu-
72
THE SKY.
가
​the children could not see what he was
doing.
"What is the matter there?" said Miss
Mary, looking out as well as she could be-
tween Rollo and Jonas.
"A man has got broken down, some how
or other," said Jonas.
"And he fills up all the road, so that we
can't get by," said Lucy.
"I think there's room enough to get by,"
said Jonas.
"But won't he want you to stop and help
him?" said Miss Mary.
"Perhaps he will," replied Jonas; "but,
if I do, the shower may come on, and so
you may get wet."
"But we can't go on, and leave the poor
man there in trouble, even if we shoud get
wet," said Miss Mary. However, we will
see when we get to him."
AC
It was as Miss Mary had anticipated
The man wanted help very much. His
wagon was very heavily loaded with large
boxes and barrels. It was drawn by a
team of four horses. One of the hind
wheels had come off, and this had let the
CLOUDS.
75
corner of the wagon, which had been sup
ported by that wheel, down to the ground.
It would be impossible for one person to put
the wheel on again alone; for it would re-
quire one to hold up the corner of the
wagon, and another to put the wheel on.
The man said that, if Jonas would stop and
help him a few minutes, they could remedy
the difficulty; but, if Jonas went on, perhaps
no other person would come along that
night, for it was a very unfrequented road.
Still the man said that he should be very
sorry to detain them, and so cause the lady
and the children to get wet.
"Never mind that," said Miss Mary; "we
shall not get wet much.'
""
Just then a low, rumbling sound of thun-
der passed along the western sky.
"There! it begins to thunder already,"
said Lucy.
"Never mind," said Miss Mary. "They
will get the wheel on very soon, I presume."
So Jonas got out, and began to assist the
man. It took more time than they had ex-
pected; for, as the wagon was, of course, al-
together too heavy for Jonas to lift it by a
direct exertion of his strength, they had to
2
ir
1
76
THE SKY.
get a pry, and also some short logs to block
ap under the axletree as fast as they got it
raised. The man cut the pry, and the logs
for the blocks, out of the woods; and, as soon
as they got the pry under, Jonas and Rollo
bore on upon the outer end of it, so as to
raise the axletree from the ground. The
man put one of his logs under it, and then
they placed the pry again, so as to get a new
hold, and thus raise it a little farther. By
this means, they gradually got it up so that
the man put the wheel on. Then he and
Jonas threw the pry and the blocks out of
the road, and all were ready to move on.
In the mean time, the cloud had risen so
that now the upper edge was quite forty-five
degrees above the horizon, and it was rising
still higher very rapidly. The wind began
to blow too; and there was a constant thun-
dering all around that part of the sky.
QUESTIONS.
How came Miss Mary to take a ride with the childre.
How were they all seated in the carryall? What appear-
ances in the sky attracted their attention as they were
coming home? How high was the upper edge of the
CLOUDS.
77
clouds when they were first observed? Repeat the con
versation in regard to the apparent rising of the clouds.
How did Jonas reason, to show that the clouds were not
really rising? Was his reasoning correct? What calcu
lation did Lucy make when she observed that the upper
edge of the clouds was about one quarter of the way from
the horizon to the zenith? What circumstance delayed
them on their way home? How did Jonas and the wagoner
manage to raise the axletree?
17*
A

78
CHAPTER VI.
THE MOVING RAINBOW.
MISS MARY proposed that Rollo should get
in behind with her and the other children,
and, if it should begin to rain before they
could get home, he would be in less danger
of getting wet. Rollo said that he did not
care if he did get wet; and he wanted to
remain where he was, with Jonas; but Miss
Mary said that she wished very much that
he would come behind; and he accordingly
yielded. Jonas also put the curtains all
down, and buttoned them snug. He said
that, unless the wind should blow very hard,
he thought that they would not get wet
behind, but he had no doubt but that the
shower would come on before they could
get home.
"And suppose the wind should blow very
hard," said Rollo; "what shall we do then?”
Why, then," said Jonas, "I suppose the
best thing I can do will be to back against it."
((

THE MJVING RAINBOW.
Lucy did not know what Jonas meant by
backing against it; and she was just going
to ask him, when suddenly a pretty loud
clap of thunder burst from the cloud at a
higher elevation than any which she had
heard before. She thought that it must
have come from a part of the cloud as much
as sixty degrees from the horizon, for it
seemed to be about two thirds of the way
from the horizon to the zenith; and Lucy
recollected that the whole number of degrees
between the horizon and the zenith was
ninety, and, of course, two thirds of the ele-
vation would be represented by sixty.
thunder frightened her a little, and the fright
and the calculation of the altitude, which
almost spontaneously passed through her
mind, made her forget to ask Jonas what he
meant by backing against the wind and rain.
The
However, she soon had occasion to learn
without asking; for, as they were ascending a
hill where the road was bounded on the side
by trees, so that it was somewhat sheltered
it began to rain a little. The foremost edge
of the cloud was now so near the zenith
that Miss Mary and the children, who sat in
the back part of the carryall, could not see it
•
:
י
-
;
80
THE SKY.
at all. The whole of that part of the sky
which was visible from where they sat, was
covered with one great expanse of dark
cloud. They could see occasional flashes
of lightning beaming over the whole of it;
and now and then a zigzag chain of glisten-
ing light darted along from one side to the
other. As they ascended the hill towards
the summit, the wind began to blow some-
what fresher, and large drops of rain began
to fall; and, when they reached the top, a
very sublime spectacle was awaiting them
upon the other side.
The roads were filled
with clouds of dust rising and driving on
towards them with great speed. The tops
of the trees were bending and roaring under
the tempest, and the streams of rain were
very visible a short distance before them,
falling from the clouds. In short, it was
very manifest that there was a great tempest
of dust, wind, and rain, close at hand, and
coming upon them in all fury.
At the top of the hill where they first ob-
tained a view of this scene, the road hap-
pened, very fortunately, to be broad and
level. Jonas, without saying a word, took a
wide sweep, ard turned round and before

THE MOVING RAINBOW.
81
the children had time to recover from their
surprise, or to ask him where he was going,
his horse was trotting fast down the hill.
"Why, Jonas," said Lucy, "what are you
going to do?"
"I am only going down the hill a little
way," said Jonas, "where we shall be shel-
tered a little; and there we shall have to stop
till the shower blows over. With the back
of the carryall to the wind, we shall not get
wet."
In a few minutes Jonas stopped. The
spot where he stopped was a little level place
in the road, below the first pitch in descend-
ing the hill. He had hardly reined up his
horse before the tempest came upon them in
all its fury. The wind roared among the
trees, and whistled by the sides of the carry-
all, and then a great puff of dust, leaves, and
sticks, came sweeping by them, and sailed
away down the hill, filling up the whole
roadway, and cutting off the whole view
of the country below. Then came the
rain, driving against the sides and back of
the carryall, and showering upon the leaves -
of the forest. The dusty road was first
spotted with the drops; a moment after-
82
THE SKY.
1
wards, it was drenched with water; and
little streams soon filled the ruts and lines
of depression, and ran swiftly down the hill.
There were several bright flashes of light-
ning, and the thunder rolled all over the
heavens. But, notwithstanding all this tem-
pest coming behind them, before them, in
the east, was a broad belt of clear blue
sky; for the cloud had only advanced about
thirty degrees beyond the zenith, so that
from its foremost edge, down to the east-
ern horizon, towards which, since Jonas.
had turned the carryall round, their faces
had been directed, there was a space of
about sixty degrees which looked clear and
serene.
The first onset of the tempest was the most
violent, and it soon abated in some degree;
but it did not abate a great deal. It settled
into a steady rain, accompanied by wind,
which Jonas knew would have driven the
rain into every part of the carryall, if they
had attempted to face it. It did not, however,
wet them at all, as they were. Jonas drew
up a leather boot, which was attached to the
dasher in front of the carryall, over his knees,
so that he was protected from what little rain

THE MOVING RAINBOW.
83
fell upon that part of the vehicle which was
not covered by the top.
The horse, however,
had no shelter, and the rain ran down his
sides, and poured off from every descending
point of his harness in streams.
They remained in this situation for nearly
three quarters of an hour; and then, when
Jonas put his head out at one side of the
carryall to look back, in order to see what
the appearance of the sky was in the west,
behind them, he said that it was breaking
away, and that fair weather was coming
again. A part of the cloud, however, was
still over their heads, so that it continued to
rain; and in the east, where the sky had been
clear and serene when they first turned round,
there was now a broad expanse of dark cloud
extending down to the horizon. When the
shower was coming on, the west was dark,
and the east was clear. Now, the condition
of the sky was reversed; the east was black
and gloomy, and the west was clear.
In fact, the brightness which now beamed
from the western sky was beginning to sur-
pass altogether that which had appeared un
the east; for the sun was in that quarter of
the heavens, and the children, though they
84
THE SKY.
!
-
were seated in the back part of the carryall
where they could not see the western sky
were still animated and cheered by seeing
the trees on each side of the road brighten
up as the sky brightened behind them;
and at last there suddenly burst forth a flood
of sunlight, gilding the whole forest, and
lightening up the distant hills.
The rain had now nearly ceased, and Jonas
thought that they might try to go home.
He accordingly turned the horse round, and
they drove up the hill. When they came
upon the broad, flat place at the top, where he
had turned at first, the rain began to drive
into the carryall again, and Miss Mary said
that, as they had waited so long, and kept
themselves dry, it was not wise to get wet
now, just to save a few minutes; and so she
proposed to Jonas to turn again, at least to
one side, and so wait a few minutes longer.
Jonas accordingly turned the horse to one
side of the road, and then backed the carryall
to the other; and, as the rain still came in,
he concluded to move entirely round, so as to
face the east again; though he said that it
would not be necessary to go down the hill,
As he turned the horse towards the east, so as

THE MOVING RAINBOW.
85
"
to bring the eastern sky again into view, th:
delight and surprise of the children were sud
denly awakened at the spectacle of a mag-
nificent rainbow, which shone out with the
greatest brilliancy from the dark mass of
clouds.
"O, what a beautiful rainbow!" said all
the children.
"Yes," said Miss Mary; "that is because
the sun shines bright, and there are a great
many drops of rain.”
"And you promised, Miss Mary," said
Lucy, "to tell us something about the rain-
bow."
"Yes," said Rollo; "you told us that it
was an optical illusion."
"I am not certain," said Miss Ma y, "that I
ought to call it an optical illusion, or not; but
there are certainly several illusions about it."
"What?" asked Rollo.
Why, in the first place, it is not nearly as
far off as we imagine. Children generally
think it is a great way off against the sky, or
where they suppose the sky to be; but the
colors come really from the drops which ara
nearest to us, and falling from the clouds too.'
"How do you know?" said Lacy.
8
86
THE SKY.
"Why, we know in this way, replied
Miss Mary." Whenever there is any rain
falling between us and the hills off at a little
distance from us, we see the rainbow con-
tinued down this side of the hills. Some-
times the lower ends of the rainbow coine
before trees or houses, so that we can see
the trees or the houses through the colors."
"Yes," said Lucy;
66 we can now."
The children all looked at the lower ex-
tremities of the rainbow before them.
They
were both continued down below the hori-
zon; and one of them was extended so low
that several objects in the landscape could be
seen through it.
"See," said Lucy, pointing to the place,
'that end of the rainbow comes down this
ide of that great gate. I can see the gate
through it.”
-
"Yes," said Miss Mary;
"that proves
that the colors which we see, come from
rops of rain falling between us and the
gate, which is not very far from us, — much
nearer than most persons imagine the rain-
bow to be. So that is one illusion. But
there is another greater than that. We are
all looking pretty nearly in the same direc

BAKERIA DREW
I CAN SEE THE GATE THROUGH THE RAINBOW.-Page 86,
"

N
ป
о
M
THE MOVING RAINBOW.
87
tion, and we think that we are looking at
the same rainbow; but it is in fact four
different rainbows that we are looking at."
"O Miss Mary," said the children, "four
rainbows!"
"Yes," said Miss Mary. "The rainbow
which each one of us sees, is a little different
from the one which the others see. I can
prove it if Jonas will drive on a little until
he gets to the other side of the road."
Jonas immediately made the horse move
along. It happened that the grass at the
side was level with the roadway here, so
that the horse went on until he came to the
stone wall, and then he stopped. The chil-
dren all the time watched the rainbow.
They found that the ends of the curve of
colors moved with them. The extremities
which had appeared to come down over the
gate slowly moved off from it in the same
direction with that in which the carryall
moved, so that now they saw a tree through
the rainbow instead of a gate. The horse
had gone towards the north in crossing the
road, and the tree stood at the north of the
gate, so that the rainbow had moved in the
same direction with the carryall.
F
4
88
THE SKY.
7
+
:
!
1
"Now," continued Miss Mary, "suppose
Rollo were to go back where we were at
first, and Lucy remain here, you perceive
that Rollo's rainbow would come down over
the gate, while the one which Lucy would
see would come down over the tree; so that
the rainbow which Lucy would see would
be a little to the north of the one which
Rollo would see. ""
"Yes; but, Miss Mary," said Lucy, “we
were all together when you said that we saw
four different rainbows."
..
Your eyes were not all together."
Pretty nearly," said Lucy.
"Then your four rainbows would be
pretty near together, but they would not be
the same. Every body, wherever he stands,
sees a rainbow exactly opposite to himself
from the sun; that is, the centre of the curve
of the rainbow is exactly opposite to his eye.
Now, no two persons' eyes can be in exactly
the same place, and of course the opposites
cannot be exactly the same; so that every
person's rainbow is different from every other
person's."
"O Miss Mary!" said Rollo. "Then there
must be ten thousand rainbows in the sky."

THE MOVING RAINBOW.
89
"L
No," said Miss Mary; "there are no
rainbows at all."
"O Miss Mary!" exclaimed the children.
They thought that this assertion was abso-
lutely incredible. As for Jonas, he did not
say any thing, but he was convinced that
all which Miss Mary had already explained
must be true; and so he had no doubt that
she would be able to establish this last asser-
tion. However, by this time the rain had
almost entirely ceased; and so he backed the
horse into the road again, and then turned on
the way towards home.
QUESTIONS.
What precaution was adopted to prevent Rollo from get
ting wet? Describe the appearances which they observed
when they ascended the hill just before the shower came
on. What did Jonas do in this emergency? Describe
the appearances when the shower came on.
How long
did they have to remain in this situation? What caused
them to stop at the top of the hill the second time? What
was the first illusion which Miss Mary mentioned in re
spect to the rainbow? How did she prove that different
persons see different rainbows? What e: traordinary state
ment did she make at last?
8*
4.
k.
90
CHAPTER VII.
THE DEW-DROP.
THEY rode a short distance in silence, ad
miring the freshness and beauty which the
whole landscape exhibited after the shower.
After a pause of some moments, Rolle
said,
"I'm sure I don't understand how we can
see so many rainbows in the sky, and yet
there be none there.”
"It does appear rather paradoxical, I con-
fess," said Miss Mary.
"Paradoxical!" repeated Lucy.
does that mean?"
(6
"What
'Any thing that is apparently contradic-
tory or impossible is said to be paradoxical,"
replied Miss Mary,
"I think that this is really impossible,"
said Lucy.
'I suppose it must seem so to you," re
plied Miss Mary; "and I don't suppose that I
shall be able to satisfy your minds about it,

THE DEV DROP
91
+
but what I said is true, notwithstanding
At least I have no doubt of it myself."
((
Why, how can we possibly see so many
rainbows in the sky," said Rollo, "unless
there are some there?'
"There is nothing in the sky, or rather in
the air, but the drops of rain," replied Miss
Mary. "Every drop of rain reflects the
rays of the sun in such a manner as to pro-
duce a number of colors. When we stand
in a certain position, we see these colors.
If there was only one drop of rain in the
sky, and the sun was shining on it, it wou'd
produce colors. But then the rays of colors.
would not all go off from the drop together.
The red rays would go off in one direction,
and the orange rays in another, and the
yellow rays in another, and the violet in
another, and so on with them all.
"So you perceive," continued Miss Mary,
we could not see all these colors from one
drop at the same time. If we were to hold
our eye where the violet rays come, then
the drop would look of a violet color. If we
then move our eyes to the place where the
blue rays come, then the drop would look
blue; and so with all the other colors. By
92
THE SKY.
moving our eye along, we should make the
colors change. This is so not only with
drops of rain, but with any drop of water. I
suppose you have often seen it in dew-drops."
"Yes," said Rollo; "Nathan found one.
the other morning in the garden. Don't
you remember, Nathan?"
The incident to which Rollo referred was
this: One morning, several days before this
ride, Nathan went out to play upon the plat-
form behind the house. The grass was wet
with the morning dew, and so he did not go
out into the yard, but remained upon the
platform, building fences for a farm with
little sticks. Presently he concluded that
he would have a stone wall around one of
the fields upon his farm, and he wanted
Rollo to bring him some little stones. Rollc
told him that he thought that he could get
the stones himself; but Nathan said that he
could not go off the platform, because the
ground was so wet that he should wet his
shoes.
Then Rollo told him that, if he stepped
down from the platform to the walk, where
there was no grass, he would not wet his
shoes, and that he might get little gravel

THE DEW-DROP.
91
stones from the walk and build his wall with
them Rollo was himself cutting wood with
his little axe in the shed, and so he did not
want to come and play with Nathan.
Rollo cut wood for about a quarter of ar
hour, and then he began to be tired; and so
he came back to see what had become of
Nathan.
He found him standing at some distance
from the platform, on the edge of the gravel-
walk, looking over very intently at some-
thing down among the grass.
"Nathan," said Rollo.
"What?" said Nathan.
"What are you looking at?
99
"Come here, Rollo," said Nathan.
Rollo ran across the platform to the gravel-
walk, and thence along the walk to where
Nathan was.
"What is it, Nathan?" said he, looking
down at the same time to the place to which
Nathan's eyes were directed.
"I saw a beautiful thing down here in
the grass," said Nathan; "and now I can't
find it."
"What kind of a thing was it?" said
Rollo.
$
94
THE SKY.
:
1
J.
:
"O, it was a very beautiful thing in
deed."
"What did it look like?" asked Rollo.
"I don't know," said Nathan, "only
was very beautiful. I guess it was a dia.
mond."
"Where was it?" said Rollo.
"There,
Nathan pointed to the place.
Rollo," said he, "it was right there among
the grass. If you would step over there, and
just push the grass away a little, you could
find it; only you must give it to me."
Rollo took a long stick, and poked about
among the grass for some minutes, but with.
out any success. He thought that Nathan
must be mistaken; but Nathan was very
positive that he saw it, and that it was a
very beautiful thing indeed; and, while they
were wondering what it could be, and what
could have become of it, they heard their
mother's voice at the window, saying,
"Children, don't go upon the wet grass."
"No, mother," said Nathan, looking down
at his feet to see that they were kept within
the limits of the walk, and were not upon
the grass at all. "No, mother, we are not
on the grass."

THE DEW-DROP.
95
"What are you doing?" said their
mother.
"Why, mother," said Rollo, "Nathan saw
something beautiful, in the grass here, and
we can't find it. I wish that you would
come out and find it for us."
So Rollo's mother came out upon the plat-
form, and walked along the gravel-walk to
the place where the children were standing.
"What did it look like, Nathan?" said she.
"It looked very bright," said Nathan.
"What shape was it?" asked his mother
66 1
"I don't know," replied Nathan.
could not see the shape very well."
"What color was it, then?" said his
mother.
"Why, it was blue," said Nathan — " or
else red. I believe it was a little red."
Nathan's mother looked about the yard a
minute, and presently she drew Nathan up
close to her, until she got his eye very near
to where her eye was, and then pointed to a
place in the grass several yards from where
they were standing, and said, -
'Look exactly there, where I am pointing,
and see if you canrot. see another one, just
like it."
i
i
96
THE SKY.
Nathan looked very intently in the direc
tion to which his mother pointed, and ther
he exclaimed,
“O, yes, there is another! Go and get it
Rollo."
"It is only a dew-drop," said his mother.
"A dew-drop," said Rollo.
"Yes," replied his mother, "a dew-drop,
reflecting the rays of the sun, so that, when
you hold your eye in a particular position,
you see the bright colors in it.
But if you
move your eye a little way, the colors all
disappear."
(6
of
Why do they?" said Rollo.
"Because," said his mother, "the rays
colors only come off from the dew-drop in
one direction; and, if you move your eye out
of the range in which they come, you lose
them, of course.'
"J
So Rollo's mother let Rollo and Nathan
try the experiment of moving their heads one
way and the other, and they found that the
colors disappeared. She explained to them
also the reason why Nathan could not find
his first dew-drop. When he stood on the
platform, she said, his eye happened to be in
the range of the red or blue rays coming
THE DEW-DROP.
97
from the drop; but, in advancing along the
wak, his eye got out of the range again, sc
that he lost all the brilliant colors; and, if he
had seen the drop at all, he would only have
scen it as a common drop of water.
Rollo and Nathan were very much inter-
ested in this explanation; and, after their
mother had gone in again, they amused them-
selves, for some time, in finding such drops in
various parts of the yard, and in making the
colors appear and disappear at pleasure by
moving their heads into and out of the range
of the colored rays.
Now, when Miss Mary alluded to the dew-
drops, in her conversation with the children
in the carryall, Rollo and Nathan immediately
recollected the circumstance above described
and they told Lucy and Miss Mary the whole
story. Miss Mary said it illustrated exactly
what she meant. "Every one of the drops.
of rain in the sky," said she, "is like a dew-
drop. It reflects the colors, only you do not
see the colors unless your eye is in exactly
the right position. That is the case with all
the drops in the air which the sun shines
apon. The drops in the red part of the
rainbow, are really no more red than those in
י
M
J
,
H
►
99
THE SKY.
..
:
4
:
:
the dark cloud beyond the rainbow, only
they happen to be in such a place that the
red-colored rays that are reflected from them
come to our eye. If we move along a little,
we get out of the red rays of these drops, and
get the eyes into the red rays of some other
drops; so that you see there are no real
curves of colors in the sky, but all the drops,
all over the surface of the clouds, reflect many
colors, and some of these colors come to our
eyes, and some do not."
"But I don't see what makes the shape of
a curve, then, in the rainbow," said Lucy.
"That is very difficult to understand," said
Miss Mary.
"I wish you would try to explain it to us "
said Lucy.
"Well, I will try," replied Miss Mary,
"but I don't expect to succeed. First, I
must tell you what the centre of the rain-
bow is. A rainbow is not generally so
large as half a circle; but suppose it was
continued in the same curve till it was made
a complete circle, then the centre of the
circle would be the centre of he rainbow
Do you understand that?"
THE DEW-DR( P.
99
The children said they did understand
that.
"Now, the centre of the rainbow," con-
tinued Miss Mary, "is always exactly oppo
site to our eyes from the sun. That is, if
we imagine a line to be drawn from the sun
in the west, straight to where our eye is
placed, and then to be continued on to the
east, it would pass through the centre of the
rainbow. Of course, if the sun is above the
horizon ten degrees, the centre of the rain-
bow will be just as far below the horizon.'
"That is, ten degrees," said Rollo.
"Yes," said Miss Mary; "and that woull
make the rainbow rather low; for the middle
of it would be below the horizon.
"And if the sun is only five degrees above
the horizon, then the centre of the rainbow
"yould be where?" asked Miss Mary.
"Five degrees below," said Rollo and
Lucy.
"And that would make the rainbow high-
er," said Miss Mary. "Now, if the sun was
exactly at the horizon in the west, then the
rainbow would be exactly at the horizon in
the east, and that would make the rainbow
higher still; for, if the centre of it was in
100
THE SKY.
•
the horizon, half of the rainbow circle wou'd
be above the horizon, which would carry the
upper part of the curve very high in the sky.
So you see the lower the sun is, the higher
the rainbow is.
"Now," continued Miss Mary, "suppose
there should be a rainbow early in the after-
would it be a high rainbow, or a low
noon,
one?"
"A low one," said the children.
"And if there was a rainbow just at sunset,
would it be a high or a low one ? 27
"A high one," said the children.
“And in the middle of the day there can-
not be a rainbow," said Miss Mary, "because
then the sun is over our heads; and the cen-
tre of the rainbow would be under our feet,
where there could be no clouds or drops of
rain to reflect the colors."
Just at this time, the party arrived at the
place where the road turned off to the house
where Miss Mary lived; and in a few min-
ntes more, they were at her door. They
wanted very much for her to explain to
them why there was such an appearance of
curves, when the whole sky was covered
with drops which all alike reflected the

i
..
THE DEW-DROP.
101
co.ors; but she said that she should not then
have time to do it.
"It is better to wait," said she. "I shail
see you all again one of these days. You
understand pretty well what I have explained.
Now, you have only got to remember that;
and also remember what the point is that you
do not understand, so as to have the line.
distinct between what you do know, and
what you do not know. You do know that
every drop which the sun shines upon, as it
falls through the air, reflects the 'colors in
certain directions, and that, if we put our
heads in the right place, we shall see the
colors. But you do not understand why it
is, that, of all the drops in the sky, we only
see the colors of those that happen to be in
the curve of the rainbow.
"Why," said Miss Mary, after she had
finished these remarks, "here's Nathan, scund
asleep."
It was true. Nathan, who was altogether
too young to understand such abstruse dis-
cussions, had laid his head back against Miss
Mary's arm, and had gone to sleep. He was
not, however, to blame for inattention. Ha
tried to understand what Miss Mary said,
1.
:
9*
102
THE SKY.
but he could not. The philosophy of he
rainbow was a subject beyond his years. Sc
he had lost himself, and sunk down inte
slumber soon after Rollo had finished the
account of their hunt for the dew-drops in
the grass.
QUESTIONS.
Relate the story of Nathan and the dew-drop. Why
was it that the dew-drop looked sometimes red and some-
times blue? How did Miss Mary say that thus incident
illustrated what she had been saying? What did Miss
Mary mean by the centre of the rainbow? Where is the
centre of the rainbow in respect to the sun? Will a rain-
bow just before sunset be a high or a low rainbow? How
will it be when the rainbow appears in the middle of the
afternoon? Can there be a rainbow at noon?. Why not?

103
CHAPTER VIII
POLES OF REVOLUTION.
ONE evening, late in the autumn, Rollo
went out with Jonas to the barn, to ascertain
what was the cause of a noise that Jonas
had heard. He was afraid that one of the
horses might be in some difficulty. The
stars were very bright that night, and, on the
way to the barn, Rollo began to look at a
long range of what appeared to be thin
clouds, which extended across the whole
heavens. Jonas told him that it was not
clouds, but stars.
"Stars!" exclaimed Rollo.
"Yes," said Jonas, "so thick together,
and so small, that they make the appear-
ance of a cloud." Jonas said that the whole
was called the galaxy.
Rollo remained in the yard while Jonas
went into the barn. After being absent a
few minutes, Jonas returned, and found Rol-
lo still looking at the galaxy,
104
THE SKY,
'What a strange thing!" said Rollo.
Yes," said Jonas, "but I think that the
strangest thing in the sky, is something
which is nothing at all."
"What do you mean by that?" said
Rollo.
"Why, I think the strangest thing in the
sky is the pole; and the pole is nothing
at all."
"Where is it?" said Rollo.
"There," said Jonas; and so saying, he
pointed to a part of the sky nearly over one
corner of the barn.
"I don't see any thing there but stars,'
said Rollo.
""
"No," said Jonas; "I told you the pole
was nothing."
"Isn't it any thing at all?" asked Rollo.
"No," replied Jonas, "nothing but a
place."
"Then I suppose something remarkable
happens there; don't there?" said Rollo.
"No," said Jonas; "there is no place in
the sky where it is so unlikely that anv
thing will happen, as there."
"A'n't there any stars there?" said Rollo.
No." said Jonas, "not exactly there, and
POLES OF REVOLUTION.
100
no stars ever go there.
The stars, ia rising.
and setting, go pretty nearly over all the rest
of the sky, but they never go there."
"How big is the pole?" said Rollo.
"It hasn't any bigness at all," said Jonas.
"Couldn't you see it through the tele-
scope?" asked Rollo.
No," said Jonas.
"Not through that monstrous great tele-
scope that Mr. Herschel made?'
""
"No," said Jonas; "because there is
nothing there to see."
"Then I don't see what good it does to
have any pole," said Rollo.
Jonas laughed; and he and Rollo both
went into the house.
Rollo went into the parlor, where he
found his father sitting at a table. He had
been reading aloud to Rollo's mother, who
was sitting at her work. He was just shut-
ting up his book when Rollo came in. Rol-
lo related to his father and mother what Jo-
nas had said about the pole. His father said
that it was all true, though he did not see
how Jonas knew any thing about it.
"I suppose," said Rollo, "that he read it
out of some book."
D
106
THE SKY.
At any rate," replied Rollo's father
"Jonas is correct; there is something very
curious about a pole of revolution in all
cases, though, as he says, in itself it is noth-
ing at all."
2
"A pole of revolution?" repeated Rollo.
"Yes," replied his father; the pole in
the heavens is a pole of revolution."
"But what do you mean, father, by a pole
of revolution?"
"Let me see," replied his father.
"Isn't
there any way for me to illustrate it to you?
-If I could think of something which I could
make revolve
66
"7
Well, father, haven't you got a half a
dollar in your pocket? If you have, you
can make that whirl on a plate."
"That would not do very well," said his
father.
"Then, father," said Rollo, "we might
take an apple, and tie a string around the
stem; and then we can twist the string, and
so make the apple whirl."
"That would not do very well either,"
replied his father; "for then the pole of revs-
lution would come in the stem."
"I don't know what that means," said
Rollo.

POLES OF REVOLUTION.
107
'You will see by and by,"
f her. "I will take a book.
an I see if I can make that whirl.
bok with printing on the cover."
replied his
I will try
Get me a
He
So Rollo went to the book-closet to look
for a book with printing on the cover.
found an Arithmetic, which had been bought
for him to study. The back of the book
was of some sort of leather, and the sides of
the cover were of paper, with printing upon
them. On one side, was the title of the
book, and on the other, a multiplication
table, and some other tables.
Mr. Holiday then took two pieces of twine,
each about a yard long, and laid them down
upon the table in such a manner that they
crossed each other at right angles in the
middle of the table, the four ends ex-
tending out towards the four sides of the
table. He then laid the book down upon
the twines at the place of crossing. He
then gathered up the four ends of the twine
over the book, and, of course, he could lift
the book up from the table. Then he ad-
justed the ends in such a manner that the
book rested in a perfectly horizontal pozi-
tion.
108
THE SKY.
"Now," said Mr. Holiday, "I must twist
the string.
""
He accordingly let the book down upon
the table again, so that it might be supported
by the table, and kept at rest while he
twisted the string formed by the four strands
of twine. When he had it sufficiently
twisted, he gently lifted the book from the
table by the string, and held it so that Rollc
could see it. It began to whirl round swift-
ly, in proportion as its weight caused the
untwisting of the string.
"Now," said Mr. Holiday to Rollo, "you
see that, as this book revolves, the outside
parts must necessarily move the swiftest."
"Yes, sir," said Rollo.
"Because," continued Mr. Holiday, "the
farther off any part of the book is from the
centre, the farther it has to go round at every
revolution; and of course it must move the
faster."
"Yes, sir," said Rollo.
"So that those letters," continued his
father, "which are near the top and bot-
tom of the cover, move swiftly in large cir-
eles."
"Yes, sir," said Rollo; "and those that are
T
POLES OF REVOLUTION.
11.
nearest the centre of the book go round in
small circles."
""
"Those that are nearest the centre of the
motion," said his father.
"It may or it may
not be exactly the centre of the book.
"There is the centre of the motion,'
continued his father, pointing to a place
upon the upper side of the book.
Rollo observed that from the outer parts
of the book, in towards the place to which
his father pointed, the circles grew smaller and
smaller, and exactly at the place were several
letters which appeared very plain. It is true
they turned round and round upon themselves,
but they did not sweep round in great circles,
like the letters farther off; and there was
one letter one that seemed to be very
near the centre of motion which Rollo
could read almost as well as if the book had
been at rest. It was an O. His father said
that the centre of motion was very near
that O.
'Now," said his father, after Rollo had
looked at it a few minutes, "you can under-
stand what a pole of revolution is. That
centre of motion which you are looking for
Um
.12
THE SKY.
is a pole.
There is another pole on the
under side of the book."
"Let me see, sir," said Rollo.
So his father lifted the book as high as he
could, so as to let Rollo look upon the under
side. Rollo said that there was just such a
centre of motion on the under side.
"Yes," said his father, "and that is the
other pole. The line running right through
the book from one pole to the other, is the
axis.
"Now," continued his father, "I can shift
the poles of revolution by slipping the strings
a little, so as to make the parts of the book
revolve about a different centre; so that
you see the axis and the poles are, in them-
selves, nothing, as Jonas said.
"Now, it makes no difference," continued
his father, "whether the book revolves
swiftly or slowly, in respect to the poles.
You can see where the centre of motion is,
when it revolves swiftly; but there would
be such a centre just as really, if it revolved
slowly. If the book only went round once
in an hour, there would still be two poles of
revolution; and so if it only went round

POLES OF REVOLUTION.
113
once in a day; only, in that case, it would
be much more difficult to find it. When
any thing is whirling round fast, we can see
by the little circular lines, which grow
smaller and smaller towards the centre,
where the centre is. In a top, if it revolves
in a true and steady manner, one pole is at
the point which the top spins upon, and the
other is just in the middle of the peg. So
in an apple, when it revolves by a string.
around the stem, the pole of revolution,
on the upper side, is generally just on one
side of the stem."
(C
Why not in the middle of the stem?"
said Rollo.
"Why, the apple," replied his father,
"usually hangs a little over to one side, be-
cause the string must necessarily be tied in a
knot on one side; so that you will gener-
ally see the end of the stem revolving itself
in a little circle; and the pole is just in the
centre of that circle.'
""
"I mean to look," said Rollo,
time I have an apple to roast.'
""
"the next
"And so," continued his father, "when
ever you throw your ball through the air,
you make it revoive as it passes along. So
10*
114
THE SKY.
a ball has its axis of rotation, and its two
poles."
"Of rotation?" said Rollo.
"Yes, or revolution. Rotation means the
same as revolution. Sometimes they call it
the axis of rotation, and sometimes the axis
of revolution. Every thing that revolves
must revolve around an axis of rotation;
even a half dollar whirling on its edge upon
a plate.”
"Let us try, father," said Rollo; "and let
me see if I can find it.”
"You can see where the upper pole is,"
replied his father. "The lower pole will be
where the half dollar rests upon the plate;
and the upper pole will be in the upper part
of the edge. The axis will run down through
the middle of the silver from one pole to the
other."
*
Rollo wanted to go and get a plate, but
his father said that he could whirl the coin
upon the table just as well. Rollo could
never whirl money himself, that way, upon
the table, because he could not keep it from
running off at the edge. But a plate, being
higher at the edges, kept it in. He found,
however, that his father could whirl it upon
POLES OF REVOLUTION.
113
the table without difficulty; and Rollo could
see very distinctly that the upper pole of its
rotation was within the edge of the coin.
"Now," said Mr. Holiday, after Rollo had
amused himself for some time looking at the
curious appearances exhibited by the piece
of money, "the whole sky is all the time re-
volving. It moves slowly, the sun, moon,
and stars, all together. The various parts
come up successively in the east, pass over,
and go down in the west. It takes twenty-
four hours for one revolution. If the revolu-
tions were very quick, for instance, a hundred
in a minute, the stars would shoot round so
swiftly that they would make bright circles
in the sky, just as the letters of ink, on the
book, made dark circles; and then, by going
out and looking, we should see at once where
one of the poles of the revolution was; for
we should see the stars go round and round
that pole, in circles smaller and smaller, the
nearer they were to it.
"But," continued Mr. Holiday, "the stars
move so slowly that we cannot see at once
where the centre of motion is; by watching
them a long time, however, we can find out.
The astronomers have found out where the
#
ه میکنید
116
THE SKY.
!
centres of motion are.
One of them is up ir
our sky, where we can see it; the other is
down out of sight, so that we cannot see it,
in this part of the world. The pole which
we can see from this part of the earth, is
called the north pole.
So now you know
what the pole is, which Jonas meant. It is
nothing in itself. It is only a centre of the
motions of other things."
"A'n't there any stars there?" asked Rollo.
"No," said his father. "There is one star
very near, which of course goes round the
pole in a very small circle, like the stem of
the apple whirling."
""
"What is the name of that star? asked
Rollo.
"Cynosura," replied his father.
"Cynosura," repeated Rollo.
"Yes," said his father; "but then people
generally call it the North Star, because it is
so near the northern pole."
QUESTIONS.
What were the circumstances which led Roli and Jonas
to talk about the pole?
Jonas made first about it?
What was the remark which
What questions did Rollo ask
POLES OF REVOLUTION.
117
about the pole? What were Jonas's answers? By what
name did Rollo's father call the pole? How did he propose
to illustrate it? What things did Rollo propose to use?
What plan did Rollo's father at last adopt? Describe how
he contrived to make the book revolve. What appear.
ances did he point out to Rollo while the book was revolv-
ing? Did Rollo see where the pole was? How did he
know where it was? How many poles were there?
How
Where was the other one? What is the axis? What did
Mr. Holiday say about shifting the place of the poles and
the axis? What other word means the same as revolution ?
What did Mr. Holiday say at last about the pole in the
heavens ?

E
118
CHAPTER IX.
RESPONSIBILITY.
SOME days after the conversation related in
the last chapter, Nathan was playing in the
green lane behind his father's house, and he
found Rollo seated upon the grass by the side
of his little wheelbarrow, very intently ex-
amining something about the wheel.
"Rollo," said Nathan, "what are you
doing?
Rollo did not answer.
"Rollo," repeated Nathan, calling louder
than before, "what are you looking at?"
The fact was, that Rollo had observed that
the wheel of his wheelbarrow was a revolv◄
ing body, and he was endeavoring to find
the poles of its revolution. He was so in-
tent upon his observations that he paid no
attention to Nathan's calls. So Nathan ran
to see what he was doing.
Rollo contrived to lean the wheelbarrow
over a little to one side, so as to free the

ROLLO FOUND SEATED BY HIS WHEELBARROW.-Page 118
RESPONSIBILITI
119
wheel from the grass, and then he could
whirl it quite swiftly by taking hold of one
of the spokes. Nathan stood by, with his
hands behind him, looking on very intently.
"What are you trying to do, Rollo?"
said he.
(
Why, I want to find the poles," said
Rollo.
"I don't understand what you mean,"
said Nathan.
"No," said Rollo ; " you are not big enough
to understand."
Here Rollo whirled the wheel of the
wheelbarrow again.
"How swift it whirls round!" said Nathan.
"I believe the pole is right in there," said
Rollo, pointing to the end of the iron gudgeon
on which the axle of the wheel revolved.
The wooden bar which passes through the
centre of the wheel, is called the axle, or the
axletree. In the ends of this axle are small
irons on which the axle turns. These irons
are called gudgeons. There are two sockets,
generally made of iron, in the ends of the
two sides of the wheelbarrow, in which the
gudgeons play. These sockets are cal.ed
the boxes. Almost all wheels that are con
120
THE SKY.
structed like the wheel of a wheelbarrow
revolve by means of gudgeons and boxes.
Nathan looked very intently into the end
of the iron gudgeon.
"I don't see," said Nathan.
"Never mind,” said Rollo. "I'm going
to wheel my wheelbarrow along now."
"No," said Nathan; "let me whirl the
wheel a little first."
"Well," said Rollo, "I'll walk towards
home, and you may wheel my wheelbarrow
along, when you have done."
"Well," said Nathan.
So Nathan sat down upon the grass, and
began to whirl the wheel, and Rollo saun-
tered along towards home.
About half an hour after this, when it was
nearly dark, Rollo and Nathan came together
into the shed where Jonas was at work split-
ting a little wood. As they came in at the
door, Rollo was saying to Nathan, "We'll
leave it to Jonas, Nathan."
"Jonas," said Rollo, when they had got
pretty near to him.
"Stand back a little," said Jonas, 'out of
the way of my axe."
"Jonas,' repeated Rollo, "mustn't Nathan

RESPONSIBILITY.
121
go and get my wheelbarrow? I lent it to
him, and so he promised that he would wheel
it in for me."
"No," interrupted Nathan, "I
""
"Stop," said Jonas to Nathan; "don't in-
terrupt Rollo. Let him tell his story through
from beginning to end; then I'll hear you "
"That's all," said Rollo, "only he won't
bring it in."
"Well, now, Nathan," said Jonas, "give
your account of it.”
—
"Why, Jonas," said Nathan, --"you
see, why, I didn't promise him at all.
I only wanted to whirl the wheel a little, and
then I wanted him to wheel it in. Besides,
I was afraid that I could not catch him.”
These statements were quite insufficient to
give Jonas any thing like a clear and correct
account of the case. However, by question-
ing the boys more fully, he at last understood
the transaction. It seems that Nathan had
continued to play with the wheel until he
found that Rollo had gone so far towards
home that he was afraid of being left alone,
and so he left the wheelbarrow, and ran after
him. Rollo, who was then just climbing
upon the gate, insisted that he should go
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11
122
THE SKY.
1
back after the wheelbarrow, and wheel it
along with him. But Nathan would not
So they had both returned to the house
without it. After a time, Rollo, feeling
uneasy at the prospect of leaving his wheel-
barrow out all night, and not being able to
persuade Nathan to go for it, had concluded
to report the case to Jonas.
"Nathan's defence is," said Jonas, "that
he did not absolutely promise to wheel the
wheelbarrow back. But I don't think the
defence is valid."
"Valid?" said Nathan; "what is valid?"
"Why, good," replied Jonas. "It is not a
sufficient defence. You did not promise in
words; but you took the wheelbarrow on
the understanding that you were to wheel it
home."
No," said Nathan, "I didn't take it at
all. It was lying right there on the ground."
"You took possession of it, I mean," said
Jonas. "You took it under your charge."
"Yes," said Nathan.
'Suppose," continued Jonas, "I were to
go to a shoemaker's shop, and ask him to
make me a pair of shoes; and suppose he
should measure me, and make the shoes, and,
RESPONSIBILITY
124
2
when they were done, I should come and
take them away. Then, afterwards, supposa
he should come and ask me to pay for them.
Ought I to pay him, or not?”
"To pay him," said Nathan.
"And suppose I should tell him that I did
not promise to pay him, and that therefore I
would not."
"Then," said Nathan,
after a moment's
pause, during which he seemed to be consid-
ering what it was best to do in such an
emergency, "then I should think he had
better take the shoes, and carry them home
again."
"But shouldn't you think I ought to pay
him?" asked Jonas.
"Yes," replied Nathan.
"Certainly," said Jonas, "because the
promise was understood. So, when Rollo
left the wheelbarrow with you, it was under-
stood that you were to wheel it along when
you had done spinning the wheel about.
Therefore you ought to have done it."
"There," said Rollo, "I told him so, Jonas;
but he said that I ought to wheel the wheer
barrow home."
124
THE SKY
*
Very well," said Jonas; "he was righ
in that."
"Right!" exclaimed Rollo.
"Yes," said Jonas; "you ought to have
wheeled up the wheelbarrow, most cer-
tainly."
"I?" said Rollo.
"Yes," said Jonas, "certainly."
"Why, Jonas," replied Rollo, "you just
said that Nathan ought to."
"Yes, but he wouldn't," said Jonas.
"Well," said Rollo.
·
"Well," repeated Jonas.
"Why, if it was Nathan's duty to wheel
it up, I don't see how it could be mine,"
said Rollo.
"The duty devolved upon you, when he
refused to do it.”
"Devolved," said Rollo.
"Yes," replied Jonas.
"It very often
happens that, when a duty belongs to one
person alone, if he refuses to perform it, it
then passes over to another person, who
from that time is under obligation to perform
it. This is a case of that kind.
It was
originally Nathan's duty to wheel up the
RESPONSIBILITY.
124
wheelbarrow; but, in the event of his refus
ing to perform it, the obligation devolved
upon you.
"For example," said Jonas, "there were
two boys, named James and John. Their
father sent them one day to carry a basket
with something in it to another house, about
half a mile from where they lived. The
basket was pretty heavy, and so he said that
James must carry it half of the way, and
John the other half. They went along till
they got a little more than half way, and
then James wanted John to carry it; but
he wouldn't. He kept running about by
the sides of the road, chasing butterflies."
"O, what a boy!" said Nathan.
"Now, it wouldn't be right, in such a case
as that," continued Jonas, "for James to put
the basket down, and leave it, saying that
he had carried it his part of the way, and
that was enough. If John wouldn't carry it
at all, then the duty would devolve upon
him. He cught not to leave his father's
property exposed there in the road. He
ought to carry it safely himself, and then
report the case to his father, when he got
home. So when you, Rollo, found that
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126
THE SKY.
Nathan would not bring the wheelbarrow
nome, you ought not to have left it there.
The duty of bringing it home devolved
upon you when he failed to perform it. So
you both did wrong, and I think that you
ought both to go together, and get the
wheelbarrow now."
The boys were silent. They did not
know what to say in reply to Jonas's argu-
ments; but they did not want to go for the
wheelbarrow.
"And if you don't go," said Jonas
Here Jonas paused.
"Well," said Rollo," what then.
""
"Why, then the duty of bringing in the
wheelbarrow will devolve upon me, and I
shall have to go."
"Why?" said Rollo.
"Because," said Jonas, "it is my duty to
see that none of the property is injured, or
exposed to injury. And so, whenever you
fail to take care of what belongs to you, I
nust take care of it."
"Let us all go together," said Rollo.
"No," said Jonas.
"Why, you say it is your duty, as wel
as curs
21
..
•

RESPONSIBILITY.
127
"(
'No," said Jonas; "I did not say it was
my duty as well as yours; but it will be my
duty when you refuse to do it. It isn't a
joint obligation that I hold with you, but
an obligation which will come wholly
upon me, when you cast it off from your-
selves. So that I have nothing to do until
you refuse to go. Then I have the whole
to do. The first thing is, therefore, for you
to say whether you will go or not. I have
no duty at all in the case until you refuse."
Rollo and Nathan stood silent, both look-
ing very grave. At length Nathan said, in a
timid voice,-
Rollo, I rather think we had better go."
Rollo did not reply.
"If you conclude to go, I can offer to go
with you; but then, in that case, I should go
only as a volunteer. It would not be in the
fulfilment of any obligation. On the other
hand, if you say you are not going, and I
conclude to go, and then you go with me,
you will go as volunteers; you will not be
fulfilling your duty by going in that way to
accompany me, after having refused to go
yourselves."
"Well, Jonas," said Rollo, "do you think
Sp
128
THE SKY.
you should go with us as volunteer, if we
should decide to go?"
"I can't tell you any thing about it,” re-
plied Jonas. "You must decide for your
selves, independently of that."
Finally Rollo and Nathan concluded tc
go; and then Jonas said that he would go
with them as a volunteer. On their way
there took place a conversation in respect
to the stars, which is recorded in the next
chapter.
QUESTIONS.
What was Rollo's object in examining his wheel, as re-
lated at the commencement of this chapter? How did he
place his wheelbarrow so as to be able to turn the wheel
easily? What is the axle? What is a gudgeon? What
request did Nathan make when Rollo was ready to leave
the wheelbarrow? Did Rollo accede to this request?
With what understanding? What dispute arose out of
this case? How did Rollo state the case to Jonas? What
did Nathan say in his defence? What was Jonas's decis-
ion? Did he consider Nathan as really engaged to bring
home the wheelbarrow? What was his supposition about
the shoemaker, to illustrate it? What did he afterwards
say about Roilo's duty? Repeat the story that he told to
illustrate this. What was the final result of the dispute

129
CHAPTER X
THE GREAT BEAR.
"JONAS," said Nathan, as they walked
along towards the great gate which led to
the pasture, where the wheelbarrow had
been left, "what was it that the boys had in
that basket that they were carrying?"
"What basket?" asked Jonas..
"The basket that James and John had to
carry, that you told us about just now."
"O, that is of no consequence," said Jonas.
"You may imagine any thing you please in
the basket."
"But I want to know what was really in
it," said Nathan.
“Jonas," said Rollo," do you know where
the pole is?"
"What pole?" asked Jonas.
"Why, the pole in the sky.
There is a
pole in the sky; and all the stars go round
t. Don't you remember you told me about
74
•
THE SKY.
130
it? and father told me some more.
a star named Cynosura close by it."
There's
"I don't know any star named Cynosura,"
replied Jonas; "but there is the North Star.
That is very near the pole.'
So saying, Jonas pointed to a star about
half way between the zenith and the horizon.
Rollo and Nathan both looked at it very in-
tently.
"Is the pole pretty near that star?" asked
Rollo.
"Yes," replied Jonas.
"Is it above it, or below it?"
"I don't know," replied Jonas.
"Couldn't you find out by some of your
books?"
"Yes," said Jonas, "perhaps I could find
out in my Astronomy. But I can't tell by
looking in the sky, the stars go so slow. It
takes the stars a whole day to go round once.
If they only went quick, we could see very
easily. If the stars about the pole whirled
round swiftly, then we could see where the
centre of the motion is. That North Star
would go round in a little circle, and the
other stars, which are farther off from the
pole. would go round in a larger circle."
THE GREAT BEAR.
131
Jonas then showed Rollo what he called
the seven Pointers. They were seven stars
arranged in a form which presented a resem-
blance to the outline of a dipper; and Jonas
said that they were sometimes called the
Dipper. Two of these stars, namely, the two
which formed the side of the Dipper, opposite
to the handle of the Dipper, pointed, as Jonas
said, very nearly to the North Star; that is,
a line drawn through them, and continued
towards the north, would pass very near to
the North Star.
"That is the reason that they are called
Pointers," said Jonas.
"But only two of them point towards the
North Star," replied Rollo, "and you said
that all the seven were Pointers."
"Yes," said Jonas; "we should not know
the two Pointers from any other stars in the
sky about as far apart from each other, if it
were not for the other five which make up
the Dipper; so that all seven of them help us
to find the North Star."
The Dipper, at the time that Jonas pointed
it out to Rollo, was pretty near the horizon;
and it was below the North Star, so that, at
this time, the two Pointers pointed rpwards
132
THE SKY,
But Jonas explained to Rollo that the Dipper
revolved continually about the pole, so that
it was sometimes off upon one side of the
pole, and sometimes upon the other; and
sometimes, he said, it was up in the middle of
the sky. In fact, upon a little reflection, Rol-
lo perceived that, if the constellation really
revolved about the pole, the Dipper must ne-
cessarily assume all these various positions in
every revolution.
"The Dipper goes round," said Jonas,
"once every twenty-four hours.
If we come
shall find it
out here to-morrow evening, we
pretty nearly where it is now; but, in the
mean time, it will have been all around the
pole, and so will have got back to its place
again. If we were to come out to-morrow
morning very early, before daybreak, we
should find that it had gone nearly half·
round; and then, of course, it would be up
high in the sky."
"I mean to get up and see," said Rollo.
Just as Rollo was expressing this deter-
mination, he happened to look towards the
house, and he saw his father coming. His
father had wondered where he and Nathan
were, and had come out to look for them.
THE GREAT BEAR.
133
"
Father," said Rollo when his father had
come pretty near, "Jonas has been telling us
about the stars. There's a constellation,
father," he continued, pointing to the stars
of which they had been speaking. "Do you
know what that constellation is?"
"Part of Ursa Major," replied his father.
"Ursa Major?" repeated Rollo.
"Yes," replied his father.
"Jonas calls it the Dipper," said Rollo.
"Very likely," replied his father.
"There
are a great many things which have more
than one name. That constellation has two.
The farmers call it the Dipper, and the
astronomers Ursa Major. That means, the
Great Bear."
"I don't see that it looks like a bear," said
Nathan.
"No," said his father, "there is not any
resemblance excepting in the tail. The
handle of the Dipper is the tail of the Bear;
and that row of stars looks a little like a tail."
"What do they call it the Great Bear for,
sir?" asked Nathan.
"Because," said his father, "it is very large
The Dipper only covers a very small part of
him. His head is away off that way."
12
134
THE SKY.
So Rollo's father pointed to the part of the
sky where the head of the Great Bear was
situated; and Nathan perceived that it was
really very large.
"Besides," continued his father, "there
is another Bear in the sky called the Little
Bear, and this is called the Great Bear to
distinguish him."
"Show us the Little Bear, father;" said
Rollo.
"The Little Bear is close to the pole,"
said his father; and so saying, he pointed to
the pole. "There is a little Dipper in the
Little Bear, only the stars which make it
are fainter. The handle of the Dipper runs
in towards the pole. The North Star is the
last star in the handle of the Dipper, and the
.ast in the tai of the Little Bear."
The children were very much interested
in looking at the two Dippers and the two
Bears; and at length, after some further con-
versation, Mr. Holiday walked along towards
the house, leaving Jonas and the boys to
follow.
Rollo said that he meant to have a ride,
and began to climb into the wheelbarrow
intending that Jonas should wheel him.
THE GREAT BEAR.
135
Stop," said Jonas; "get out a minute,
while I put a cushion in."
So Rollo got out of the wheelbarrow
again, and Jonas began to gather some tall
brakes which grew near the path, and to
strew them in the bottom of the wheel-
barrow, so as to keep Rollo's clothes from
being soiled by the wheelbarrow. Then
Rollo and Nathan got in, and Jonas began to
wheel them along towards the house.
The boys sat in the wheelbarrow, with
their faces towards Jonas; and pretty soon
they wanted him to tell them a story.
"Well," said Jonas, "I will. Once there
was a boy, and he had a room where he used
to study. He had a fire in his room, because
it was winter. His father charged him that,
whenever he went out of his room, he should
take the fire down off the andirons; for he
said that, when a stick of wood was left
burning upon the andirons, there was great
danger that it would burn in two, and the
ends fall down, and some coals roll out, and
set the room on fire."
"Yes," said Rollo: "my father told me a
story of a room that get on fire in a tavern,
once, in that way."
136
THE SKY.
"What was the story, Rollo?" said Na
than. "Tell it to me."
"No," replied Rollo; "I want to hear the
rest of Jonas's story now."
"Well," said Jonas, proceeding with his
story, "the boy usually neglected to take
his fire off the andirons, notwithstanding
his father's injunctions; and his father was
afraid that, some time or other, his fire
would fall down, and the house get burned
up."
"I would not have let him have any fire,"
said Rollo, "if I had been his father."
"One day," continued Jonas, without
taking notice of Rollo's remark, "his father
went into his room, and he found a stick
lying across the andirons, nearly burned off.
So he took the tongs, and broke it in two
gently, and laid the ends over in the corners,
as if the stick had burned off, and fallen
Then he took two or three coals, and
laid them out on the hearth near the floor,
and one large coal he put out upon the floor,
about six inches from the edge of the hearth;
and then he went away."
over.
"Why, Jonas," said Rollo; "tha would
set the house on fire."
THE GREAT BEAR.
137
"After he had waited some mitutes,'
continued Jonas, "until he thought it was
time for the fire to begin to blaze up, he
called to the boy, who was out in the yard,
and asked him to go into his room, and bring
him out his dictionary. So the boy went in,
and presently came running out, and said his
room was on fire. So his father ran in, and
poured some water on the place, out of a
pitcher, and put it out. The boy was very
much frightened. He thought that the stick
1ad fallen down of itself, and that he had
almost burned his father's house up."
Here Jonas put down the wheelbarrow;
for he had got to the great gate, and of course
he had to stop to open it. When he had
opened the gate, he wheeled the boys
through, and then stopped to shut it.
"That was a good plan," said Nathan.
"No," said Jonas, "I don't think it was a
good plan."
"Why not?" said Nathan.
"Why, it wasn't honest," replied Jonas.
"Children ought always to be honest with
their parents; and parents ought to be honest
with their children."
!
:
F
i
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138
THE SKY.
QUESTIONS.
Had Jonas spoken to Rollo about the pole before this
On what occasion? What two names has the bright sta.
which is near the pole? What did Jonas call the stars by
which he found the Pole Star? How many of them are
there? In what form are they arranged? What is the
astronomical name of the constellation? Does the Great
Bear include more or less than the seven Pointers? Is it
a large or a small constellation? What other constellation
did Mr. Holiday show them? Relate the story which
Jonas told the boys in coming home. What was Jonas's
reflection on this story?

139
CHAPTER XI
ORION.
MR. HOLIDAY's business often led him
away from home for a distance of twenty or
thirty miles, and on such occasions he often
took Rollo and Jonas with him. Jonas went
to drive, and to take care of the horse, and
Mr. Holiday used to allow Rollo to go, be-
cause he always enjoyed such excursions very
much; and, besides, he generally derived in-
struction, as well as amusement, from them.
One morning, in the early part of the
winter, Mr. Holiday said, at the breakfast-
table, that he was going away that day to
come back the next; and Rollo immediately
proposed to go with him.
"Very well," said his father. "I have no
objection. You may tell Jonas to have the
horse and sleigh ready at ten o'clock; and
ell him to put in the front seat."
The sleigh in which Mr. Holiday used to
make his journeys, when the ground was
140
THE SKY.
i
covered with snow, had two seats. The
back seat was fixed, but the front one was
movable, so that it could be taken out and
put in at pleasure. When only two persons.
were going to ride, Jonas usually took out
the front seat, and put it away in the chaise-
house. But when more than two were to
ride, then he would put it in.
When Jonas drove Mr. Holiday on his
excursions, he always rode upon the front
seat, for it was not only nearer the horse,
but it was also higher; so that for a double
reason it was the most convenient seat for a
driver to occupy. Rollo, however, when he
rode with his father and Jonas, sometimes
rode on the front seat with Jonas, and some-
times on the back seat with his father.
When it was pleasant, and the cold wind did
not blow much in his face, he sat upon the
front seat, where he could see better. But
if he became cold, he usually sat in behind
with his father, where it was much more
easy to keep warm.
The day on which Rollo took the ide
which is to be described in this chapter, it
was very pleasant. The sun shone and the
air was still, and as the direction of their
ORION.
141
ourney was towards the south and west,
the rays of the sun shone upon them fully,
for many hours. They reached the place
of their destination about the time the sun
went down. It was a pleasant little village.
Jonas went to take care of the horses at the
stable, while Rollo and his father went into
the house. Mr. Holiday ordered supper, and
then went out into the village to find the
man with whom he was going to do his
business. In the mean time, Rollo waited
in the little parlor where the tea-table was
to be set. There were some books on a
table in the room, and he sat down before
the fire, and began to read the books.
In about half an hour, his father came in,
and Rollo asked him if he had finished his
business.
"I do
"Why, partly," replied his father.
not know but that I shall have to go on ten
miles farther, this evening. If I do, should
you prefer to go too, or to wait here by this
comfortable fire?"
"I should rather go, a great deal,” said
Rollo.
"It will be pretty cold," said his father
142
THE SKY.
"Never mind," replied Rolla. "I sha'n't
mind the cold."
"We had the sun's rays upon us this
afternoon," said his father, "which kept us
warm. But you will find it very different
this evening. Besides, we have got to go
across a large pond, where it will be bleak,
if there is any wind."
The argument of the pond, instead of
operating to induce Rollo to remain where
he was, only increased his desire to go; for
he thought that it would be very pleasant to
ride over a pond, in a winter's night, by
starlight.
Mr. Holiday was willing that Rollo should
decide the question for himself. In fact, he
thought that he would not be very cold if
he should go with them, for they had four
buffalo skins in the sleigh, which were very
warm; and he knew, therefore, that Rollo
could be well protected from the cold.
Accordingly the plan was so arranged, and
after tea Jonas brought the horse and sleigh
up to the door. When Rollo first canie out,
he thought it was not very cold. He had
become well warmed in the little parlor,
ORION.
143
and he was much wrapped up with clo
thing.
He had on thick boots and a warm great-
coat, lined and wadded.
He wore a fur cap
upon his head, which covered his ears, and a
fur tippet about his neck.
It was, however, really very cold, although
Rollo did not begin to feel it much at first.
But, though cold, it was a pleasant evening.
There was very little wind, and there were
no clouds.
"O father," said Rollo, looking up; "look
at the sky; see how full of stars it is.”
The sky was indeed very full of stars.
The galaxy, or the milky way, as it is
sometimes called, was very bright. Rollo
looked at the stars a moment, and then he
got into the sleigh. His father advised him
to take a seat with him, behind; but Rollo
said that he wanted to sit with Jonas, and
see the pond, when they came to it.
"I am afraid you will be cold," said his
father.
"No, sir," said Rollo; "I don't think it
is cold."
So Rollo took his place, by the side of Jo-
pas, on the front seat. and they rode along
144
THE SKY.
After going at a brisk pace for a few miles
they came to the top of a hill, where the
pond first appeared in sight. It looked like
a great level field covered with snow. They
could see a dark line winding along in a
gently-serpentine direction across the surface
of it. Jonas said that this was the road
which they were to take in crossing the
pond.
The horse went rapidly down the hill,
and before long they were upon the pond.
There was not much wind, but a light
breeze blew keenly towards Rollo's face, and
made his nose and his cheeks cold. So hẻ
said he meant to turn round, and face towards
his father.
His father proposed to him to come and
sit upon
the back seat; but he said he should
be warm upon the front seat, if he only
turned round. So he put his feet over the
seat, and enveloped them in the buffalo skins
which were down in front of the back seat,
and the buffalo which had been before him
he drew up over his shoulders, so that now
he had a very good place indeed. He could
see, all around him, the shores of the pond
with the lights in the farm-houses on the
ORION.
147
land, and all the constellations which were
spread out before him in that quarter of the
heavens, towards which he was looking.
"O father," said Rollo, "I see three stars
I wish I knew the names of
Could you look round and see,
all in a row.
them,
father?"
66
Why, not very well," said his father.
"I cannot look round, I am so muffled
up."
Rollo, being seated on the front seat, with
his back to the horse, of course was looking
at that part of the sky which was behind
the sleigh, so that his father could not see
the constellations in that quarter of the
heavens.
"Let me see," said his father; "we must
be going nearly west, so that that part of
the sky is the eastern part. Orion must be
rising about this time. Perhaps the stars
which you see are the stars in the belt of
Orion."
"In the belt of Orion?" repeated Rollo
"Yes," said his father.
"The most
beautiful constellation in the sky is Orion;
and early in the winter it rises in the even-
ing. Orion was a hunter, and he has a
148
THE SKY.
belt and in his belt are three beautiful
stars, al' in a row.”
"Well, father," said Rollo, "tell me some
other stars that ought to be near, if it is
really the belt of Orion that I see, and then
I will tell you if they are there."
"Very well," said his father. "If they
are the three stars in the belt of Orion, they
lie in a line one above the other, not one by
the side of the other. I mean by that, that,
if there was a line drawn through them, and
continued each way, it would be a line run-
ning up and down in the sky, not a line ex-
tending from one side to the other."
"Yes, sir," said Rollo; "this row of stars
is in a line up and down."
"And off on each side of the little row of
stars are two other bright stars, one on each
side."
"How far off, sir?" said Rollo.
"About twice as far, I should think, as
the length of the little row of stars."
""
'Yes, sir," said Rollo; "I see one of them.
Yes, I see them both. One is off on one
side, and the other is on the other side."
"Yes; then I have no doubt it is Orion
that you see. One of the stars that you
orion.
149
last found is in his foot, and the other is in
his shoulder."
"I wish I could see his shape," said Roilo,
all drawn out in the sky."
"It would be very convenient, I have no
doubt," replied his father. "Pretty near the
lowest of the three stars in the row, there is
a faint cluster of stars, towards the south."
"Yes, sir," said Rollo; "I see them."
"They are in Orion's sword," said his
father.
"I see them," said Rollo.
"Now, look at all the stars in the constel-
lation again, and notice how they lie in re-
spect to each other, so that you will know
the constellation when you see it again.
""
"Yes, sir," said Rollo; "I mean to look.
for it every evening; only I shall forget where
to look."
"You must look in the east, at this time
of the year, and at this time of the evening.
In the spring of the year, Orion is in the
west in the evening. Orion rises in the
east, and passes over just like the sun, every
day, and sets in the west. Only in the
autumn, and early in the winter, he rises in
the evening, and sets in the morning; and
13*
150
THE SKY.
m spring, and early in the summer, he rises
towards the morning, and sets in the evening.
If it were April now, we should see Orion
in the west, at this time of the evening,
just going down.
During this conversation, Jonas looked
round several times to see Orion. He told
Mr. Holiday that there was a very bright
star down near the horizon, and pretty
nearly in a line with the little row of stars
in Orion's belt.
"Yes," said Mr. Holiday; "that is Sirius,
-the brightest star in the sky. Do you
see it, Rollo ?”
"Yes, sir," said Rollo, pointing; "there
it is.'
""
"There is one more star for you to find,"
said Mr. Holiday, "and that will do for your
icsson to-night.'
""
"What is the name of it, sir?" asked
Rollo.
"Aldebaran," replied his father.
"Alde.
baran is opposite to Sirius, almost in a line
with the little row, only above, and about as
far above as Sirius is below.”
Rollo and Jonas locked for Aldebaran
but they were not sure that they found it

ORION.
151
So Mr. Holiday turned part.y round, and
showed them Aldebaran. Aldebaran was
quite high in the sky, and Sirius was quite.
low, and the little row of stars in Orion's
belt was between the two, and pointed on
the one side to the one, and on the other
side to the other. Thus it was that Rollo
came to know Aldebaran, and Sirius, and the
bright constellation of Orion.
QUESTIONS.
What were the circumstances of the ride described in this
chapter? At what season of the year was it? Did they
intend to ride in the evening, when they left home? How
came they to ride in the evening? How were the party
seated when they set out in the evening? What change
did Rollo make in his position when they came upon the
pond? What is the name of the constellation which at-
tracted Rollo's attention? Towards what quarter of the
heavens was he looking? How many stars did he notice
particularly at first? In what part of the figure of Orion
are these three stars situated? What are the names of the
other two stars which Rollo learned? How is Sirius situ-
ated in respect to the three stars in Orion's belt? How is
Aldebaran situated? Where are these stars in the evening
in spring?
י
4
J
152
CHAPTER XII.
SIRIUS.
ROLLO was very much interested in the
information which his father gave him al ou
the constellation of Orion, and the stars in
its vicinity. Jonas was much interested too.
He took great pains to fix the names and the
relative position of the stars in his mind.
He was more careful to do this than Rollo
was; for he was aware that, if he should.
forget any thing which Mr. Holiday had
said, it might be very long before he should
have a suitable opportunity to ask him to
repeat it. Accordingly, for several evenings
after this, he went out and looked at these
stars, repeating to himself their names, and
noticing particularly their respective situa-
tion, so as to impress the knowledge which
he had acquired as firmly as possible upon
his memory. Rollo, however, thought little
more about it all winter.
Towards the close of the winte, how
SIRIUS.
153
ever, a circumstance occurred which brought
the subject up to his mind again. It was in
February, near the close of the month.
There had been a rain storm which had
melted the snow very much. The streams
had been swollen so as to overflow their
banks, and large pools of water were formed
in all the low places in the fields. Down
upon the meadows, too, in front of his fa-
ther's house, there were large ponds of water
formed by the overflow of the brook which
ran through it.
After the rain, the wind blew cold from
the north-west for two days, and this was
succeeded by a hard frost, which continued
for several days and nights, until all these
pools and ponds were frozen over. Rollo
wanted to go down upon the meadows, and
skate. His father said that he might go.
So he took his hand-sled, and put Nathan
upon it, giving Nathan his skates to hold;
and thus he proceeded down towards the
ice, drawing Nathan over the icy surface of
the ground.
The sled was what boys call a framed
sled; so that it was quite light, though it
was pretty large. It had a wooden tongue
154
THE SKY.
Instead of a rope, to draw it by. A tongue
is better than a rope, because you can push
the sled by a tongue, as well as pull it; and,
besides, by means of a tongue the sled can
be turned round more easily.
Rollo asked his father if he might make a
fire upon the ice that afternoon. He thought
of this after he had started with Nathan; so
he went to the parlor window, and knocked,
and asked the question.
"No," said his father; "you must not
make a fire. But if you will collect a heap
of sticks and logs, for fuel, we will all go
down this evening, and set it on fire.”
Rollo liked this plan very much. So he
went back to Nathan, and told him. Nathan
asked Rollo if he thought that his father
would let him go down and see the fire.
"Yes," said Rollo, "if you'll help me
'make the pile of wood.'
"Well," said Nathan, "I will.”
So Rollo and Nathan went down to the
meadows together.
When they reached the ice. Rollo put on
his skates, and Nathan took his seat upon the
sled, ready for Rollo to give him a ride
'There were four stakes set into the sides of
SIRIUS.
15A
the sled, two on each side. Nathan sa. with
his back towards the forward part of the
sled, because Rollo was going to push him.
and not draw him; and of course he must
sit with his back to Rollo in order to face
the way that he was going.
When Rollo was ready, he took up the
tongue, and began to skate slowly along
pushing the sled before him.
The sled glided smoothly over the ice;
and Nathan had a fine ride, until at length
they came to the place where Rollo said it
would be well for them to make their fire.
The pond at this place was at the margin of
the meadow, where it was bounded by high
land covered with forest-trees. The snow
had been nearly melted away from this hill
side, and Rollo saw that there were a great
many sticks and half-decayed branches lying
about upon the ground.
"Now, Nathan," said Rollo, "here is
plenty of wood for our fire, only I can't ge
and get it, because I have got my skates on.
You must go up under the trees, and throw
the sticks down to the edge of the ice, and
I will put them upon my sled, and so draw
I
156
THE SKY.
them off to the place where we are going to
have the fire."
Nathan approved of this arrangement, and
the boys worked industriously more than
two hours, until at last they had made quite
a large heap of fuel. They piled it up upon
the ice near the middle of the pond. Na-
than said he thought that it would make a
magnificent fire.
After they had collected all this fuel, Rol-
lo gave Nathan some more rides upon his
sled, and then they went home. It was not
quite tea-time, and so the boys went out to
find Jonas, to tell him about the fire, and to
ask him if he would go down with them in
the evening, and see it burn.
"Yes," said Jonas, "and we will look for
the stars in Orion. I have not looked for
them these two or three months."
"
'No," said Rollo; "it won't do any good.
I don't believe we can find them. They
must be all scattered about before this time."
"Why, no," said Jonas; "they don't get
scattered about. The stars always keep
together, just in the same places."
"No," said Rollo; "father said they
moved about the sky"
SIRIUS,
157
"Yes,' replied Jonas, "they move over
the sky but they all move together, and
keep as far apart from each other at one time
as at another, all the way. . They don't
move about among each other at all.”
"Don't they?" said Rollo.
"No," replied Jonas; "certainly not.
Those three stars in Orion's belt have been
in just such a row always; and they never
move out of it; and Sirius has been just so
far from them, off at one side."
"Then perhaps we can find them to-
night," said Rollo.
"Yes," replied Jonas; "I have no doubt
we can. Only they will not be in the east.
Your father said that they were in the west
in the evenings in spring, and it is pretty
nearly spring now."
"We'll look in the west, then," said
Rolo.
"Or overhead," replied Jonas; "perhaps
they have not got farther than overhead
yet."
Jolas was right in his expectation of find-
ing the constellation of Orion, and the bright
stars near it. For, when they went down
that evening, they saw the stars forming that
i4
158
THE SKY.
constellation, and also Sirius and Aldebaran
in precisely the same relative situation in
respect to each other which they had occu
pied earlier in the winter, though the
whole group was now in a different part of
the sky.
There was, however, one bright star be-
tween Sirius and Orion which Rollo did not
recollect seeing there before.
"No," said his father, "it was not there
before. It has come among these constella-
tions. It is one of the wandering stars.'
"2
"Wandering stars," repeated Rollo.
"Yes," said his father. "Almost all the
stars keep exactly the same places in respect
to each other. They all rise and set, it is
true; but then they go together, and each
keeps its own fixed place among the rest.
But there are a few that go wandering about
among the rest, sometimes here, and some-
times there."
"How many are there, sir?" asked Rollo.
"There are only four that are very bright."
"What are their names?" asked Rollo.
"Venus, Mars, Jupiter, and Saturn," re-
plied his father.
"Which is this one coming into Orion?'

SIRIUS.
159
"I don't know," said his father.
haps it is Jupiter."
"I wish I knew," said Rollo.
'Per
Nathan was impatient to go and set their
heap on fire, and so the whole party walked
along. Rollo's father and mother were both
with them; and, when they got to the ice,
Rollo put on his skates, and skated along to
he place, pushing Nathan before him on the
sled, as he had. done in the afternoon. His
father and mother walked along upon the
hard snow at the margin of the ice, until they
zame opposite to the heap of fuel, and then
they walked carefully over the ice to it.
The heap burned well, and it made a
beautiful fire, which illuminated the whole
held of ice, and gleamed on the forests and
hills around.
After a short time, Rollo's father and
mother concluded to go home, and they told
Rollo and Nathan that they might remain
there with Jonas for about half an hour.
"How can I tell when it is half an hour?”
said Rollo.
"," said his father, "you can guess pretty
no you can tell by Sirius. See,
as we stand here, you observe that it appears
Hear
160
THE SKY.
¿
?
a little way above the top of that tree over
on the bank."
"Yes, sir," said Rollo.
"Well, now you may wait until Sirius
gets down into the tree.'
1.9
"Well, sir," said Nathan.
"Only," continued his father, "you must
be careful to stand in exactly the same place
as now, when you make your observation."
"Yes, sir, I will," said Rollo.
So his father and mother walked slowly
away. After they had gone a short distance,
Rollo called out, in a loud voice,-
"Father!"
"What," said his father, looking round.
"Will you just tell me the name of that
little cluster of stars out there a little way
beyond Aldebaran?"
"Yes," said his father; "the Pleiades."
QUESTIONS.
Describe the manner in which the sheets of ice were
formed, as stated in this chapter. Describe the sled which
Rolo took with him to the ice.
upon it, when taking his ride?
How was Nathan placed
In what manner did they
arrange their work in getting the wood? What conversa
-
YOU WAIT UNTIL SIRIUS GETS INTO THE TREE.-Page 160,
.
י


SIRIUS.
161
tion did Rollo hold with Jonas about the stars? Lid Rolle
expect to be able to find and recognize Orion? Why not?
What did Jonas say? Did they find Orion? In what
quarter of the heavens was it? What other stars did they
find? What did Rollo's father say about wandering stars?
What are the names of the four brightest? What is the
name of the cluster which Rollo asked his father about
wher he was going away? Where is it situated?
14*
:
162
CHAPTER XIII.
PARALLAX.
ONCE upon a time, Rollo and his father
were travelling in a steamboat by night, when
an opportunity occurred to teach Rollo some-
thing about the distance of the stars, and the
mode by which the astronomers determine
the distance.
The route which Rollo and his father
were taking, was one which was performed
partly by steamboat, and partly by railroad;
and it was so arranged that they were to
reach the port where the passengers were to
be transferred from the boat to the cars, at a
little after midnight. They were then to
continue their journey on the railroad, and
reach their place of destination in the morning.
About half an hour before it was time ior
the boat to arrive at the port, a waiter walked
through the cabin of the steamboat, between
the rows of berths and cots, which were filled
with passengers sleep, ringing, as he walked,

PARALLAX:
163
a huge bell, wnich was intended to wake the
passengers up. Rollo was sleeping in a berth
directly over his father's. He lifted up his
head, looked around eagerly, and, as soon as
he recollected where he was, he looked down
into his father's birth, and said, --
"Father, what is that bell for? Is it for
fire?"
66
No," said his father; "only to wake
us up."
"O!" said Rollo, in a tone of voice
which expressed that he felt relieved. Rollo
would not seriously have supposed that the
bell was for fire, if he had been fully awake;
but, being suddenly aroused by such a loud
sound, in such a strange place, it is not sur-
prising that he was a little alarmed.
When Rollo found that the bell was for
them to get up, he was in great haste to obey
it. His father was much more deliberate in
his motions, and at length Rollo told his
father, that he thought they had better be
quick, or the steamboat would get to the land,
and the cars would go off and leave them.
"No," said his father; "they generally
give us time enough."
Just then, Rollo heard a little bell ring
164
THE SKY.
that sounded as if it was up on deck. It
was a bell in the engine-room, but it was
rung by a man in the wheel-house. The
wheel-house is a small room or closet, with
windows in front, built on the deck, in the
forward part of the boat, where the helms-
. man stands to steer. The windows in the
front of the wheel-house are for him to look
out, and see where he is going. In pleasant
weather, he has these windows open; but
when it rains or snows, or when the wind
blows heavily, he keeps these windows shut,
and so looks through the glass.
There is a large wheel in this place, which
is the reason why they call it the wheel-house.
The wheel has handles to it, all around, for
the man to take hold of, to turn the wheel
one way or the other. There is an axle to
the wheel, and a rope passes once or twice
round the axle. The two ends of the rope are
carried along the whole length of the vessel
to the stern, where the rudder is. The ropes
pass on the under side of the promenade deck
on little pulleys. The ends of the rope are
fastened to the rudder, one on one side, and
one on the other. Thus the man who stands
m the wheek ouse can look out forward
:
PARALLAX.
168
through the windows, and see which way
the steamboat ought to go; and then he can
turn the wheel one way or the other, and so
steer the boat just as he pleases.
'There is also in the wheel-house a little
beli-pull, with a wire leading from it to the
engine-room. The end of the wire in the
engine-room is connected with a bell, so
that the helmsman, while he is steering the
steamboat in the wheel-house, can make the
little bell ring in the engine-room, whenever
he wants the engineer to stop the engine.
Now, it happened that, while Rollo and his
father were preparing to come up from their
cabin, the helmsman saw a sloop before them,
which was sailing almost exactly across their
course. So he pulled the bell, to make the
engineer stop the engine, until the sloop
should have time to get by
Rollo understood this; at least he under-
stood that there must be some difficulty in
the way of going forward, for he had very
often stood by the wheel-house to see the
helmsman steer; and he had watched him,
when there was any difficulty in the way,
and had seen how he made the signal to the
engineer. He wanted his father to make
166
THE SKY.
haste, and go up, and see what the difficul
ty was.
"You may go up whenever you are
ready," said his father, "and I will come up
by and by."
So Rollo went up the cabin stairs, and
came out upon the main deck. Here, how-
ever, he could not see very well; so he went
around to the little staircase which led up to
the promenade deck. Before he got up, the
bell was rung again, and the engine put in
motion, so that by the time that he reached
a place where he could see, the boat was go-
ing on as rapidly as ever, and the sloop was
but just visible, as she was rapidly receding
into the distance, off on one side of the boat.
There were two or three stools under an
awning, near the place where Rollo was
standing, and he sat down upon one of them.
In a short time, his father came up, and took
his seat at his side.
"How long will it be now, father, before
we shall get in?" asked Rollo.
"I should think it would be twenty min
utes," replied his father.
"And what shall we do all that tim
said Rollo..
PARALLAX.
167
"O, we can sit here and look at the stars
I can see several different kinds of stars; at
.east, what we might call stars."
"How many?" asked Rollo.
"Why, in the first place," said his father,
"there is Sirius.”
So saying, his father pointed to a bright
star which was before them, about thirty
degrees above the horizon.
"Is that Sirius?" said Rollo.
(6
Yes," replied his father.
Then he pointed to another star, which
looked very much like Sirius, only it was
not quite so bright, and he said that that
must be a planet.
"How do you know that it is a planet?"
asked Rollo.
"Because," replied his father, "I know
there isn't any star which belongs there."
"Is not a planet a star?" asked Rollo.
Why, we may call it a star, just as we
may call those little sparkles in the water
stars," replied his father.
"What little sparkles?" said Rollo.
"Come with me,” replied his father, "and
I will show you."
So Rollo went with his father to the side
168
THE SKY.
of the boat, and they looked over together.
'T'he water came foaming along the side from
under the paddle-wheels, and in the midst of
it, Rollo perceived, every now and then, a
bright spark which sailed along a moment,
and then became suddenly extinguished.
"There," said his father, "we might call
those sparkles stars.
For instance, a man
might say that he looked over the bows of
the boat, and saw the water full of little
stars."
"But, father," said Rollo, "the water is not
full; there is only now and then one."
66 I
presume we should see more of them
at the bows," said his father.
·
"Well," replied Rollo, "let us go and
look."
So Rollo and his father walked along to-
gether to the forward part of the boat, on the
promenade deck. The promenade deck is
the upper deck. Rollo stopped a moment,
when they reached the wheel-house, to look
in at the man who was steering.
It was
almost dark in the wheel-house.
two small boxes which had compasses in
them, for the man to steer by, when there
was no land in sight. There was a light in
There were

FARALLAX.
169
each of these ooxes, which was placed in
such a manner, as to shine upon the com-
pass, so that the helmsman could see which
way the needle pointed; but it did not shine
much into the wheel-house itself.
"I should want a great deal more light
than that," said Rollo, "if I was going to
steer."
"I suppose that the helmsman would like
to have more light, if he could," said his
father.
"Well, he might have more," rejoined
Rollo. "He might have a good bright lamp
hung up in his wheel-house."
"That would not do any good," said his
father, "for that would only illuminate the
things that are in the wheel-house; and what
he wants to see, are the things out over the
water, such as the vessels coming and go-
ing, and the land. If he could have a light
which would shine upon them, it would do
very well; but to have a bright light hung
up in the wheel-house, would only tend to
dazzle his eyes."
"Yes," said Rollo: "I did nɔt thnk of
that "
15
·
THE SKY.
170
•
"They always keep the wheel-house dark,
for the eye is more sensitive in the dark,'
said his father. "They have a small light
to shine upon the compass-card, and that
is all."
The promenade deck did not extend any
farther forward than the wheel-house; so that,
while Rollo and his father had been holding
the preceding conversation, they stood at the
end of it, near a railing which passed across
in a line with the forward part of the wheel-
house. At length Rollo said,
Come, father, let us go and see the
sparks."
There was a steep ladder which led down
from the forward part of the promenade deck
to the forecastle. Rollo and his father de-
scended this ladder. As soon as they reached
the deck below they walked forward to the
bows, where they climbed up, upon the bul-
warks, and looked down to the water.
The boat was moving swiftly along, so as
to plough up the water with great force, and
Rollo saw, to his great delight, that the
dashing waves were, to use his fathers ex-
pression, full of stars. They looked like

PARALLAX.
171
sparks of fire, which came flying out on each
side of the cut-water, and glided swiftly along
the bows.
"What makes them ?" said Rollo.
66
"I don't know," replied his father.
Why, father!" said Rollo; "don't you
know?
"No," replied his father. "I have heard it
said that they are produced by some kind of
animalculæ in the water."
"What are animalculæ ?" asked Rollo.
"The word animalculæ means small anı-
mals," replied his father.
"Some people
say that these little stars are some kind of
animalculæ ; but if they are, I don't under-
stand why they don't shine, except when
the water is agitated. You see that where
the water is dashed away each side of the
bows, and where it comes out from under the
paddle-wheels, we see those stars; but they
do not shine where the water is still.'
""
After looking at these stars in the water
for some time, Rollo and his father went
back to their seats under the awning. Here
Rollo's attention was soon attracted by the
sight of a star, as he supposed, which was
**
172
THE SKY
very near the horizon. He pointed t out to
his father.
"Yes," replied his father, "I saw it be
fore we went away. It looks precisely like
Sirius, or that planet; but it is really a very
different thing."
"What is it, sir?" said Rollo.
"It is a lighthouse, I presume," replied his
father.
"What makes you think it is a light-
house?" asked Rollo.
"I judge from the distance that it is from.
us," replied his father. "It cannot be but a
few miles off."
"How do you know? I could not tell
any thing about how far off it is, by the looks
of it. It looks to me exactly like Sirius."
"I cannot tell by the looks of it," said his
father. "I do not see any difference myself
between the appearance of the light and
that of Sirius, unless one is a little brighter
than the other."
"Then how can you tell how far off it
is?" asked Rollo.
66
By its parallax,” replied his father.
"Its parallax," repeated Rollo. "What is
't's parallax?
PARALLAX.
173
"Something too difficult for you ?. un-
derstand,” replied his father.
"Can't I understand any thing about it a
all?" said Rollo.
"Why, yes," rejoined his father. "I don't
know but that I can explain something to
you about parallax; but it will not be much "
"Well, sir," said Rollo, "explain as much
as you can.'
""
"When we went away from here to go
and see the stars in the water, at the bows
of the boat," said his father, "I observed that
that light was off in this direction."
So saying, Rollo's father pointed to a part
of the horizon farther forward than where
the light then was, and he explained to Rollo
that, since they had left their places to go to
the bows, the light had glided along the
horizon from that point to the place where it
then was.
66
"Now, all this time," continued his father,
we have been going along ourselves in a
straight line."
"How do you know, sir?" asked Rollo.
"Because," replied his father, "Sirius ap-
pears in the same direction from us, that it
did before we went away; and that shows
་
15*
THE SKY.
1
that we have not altered our course.
But
the light has moved along the horizon several
degrees; so that it appears, now, in a very
different direction from what it did before,
And yet it has not moved itself; it only
changes its direction because we move."
"How do you know," asked Rollo, "that
it does not move itself?"
(6
Why, I don't know what movable ligh
there could be there."
"There might be a man," replied Rollo
"carrying a lantern along the shore."
"But the light of a lantern could not be
seen so far," rejoined his father.
Perhaps it is not very far," said Rollo.
"We may be pretty nigh the shore."
"But we have sailed two or three miles,
at least," replied his father, "since I first
saw the light. Now, if we were so near the
shore as to be able to see the light of a lan-
tern, we should have got by it entirely before
this time, and have left it far behind us.
But, though we have sailed two or three
miles, the light has only advanced along the
horizon a little way; and so I judge that it
must be five or six miles off. And if it is
five or six miles off, it must be some large
PARALLAX.
175
ight; and I cannot think of any thing which
t is likely to be, except a lighthouse."
"I rather think it is a lighthouse myself,'
said Rollo.
66
'If we watch it," said his father, we
shall see that it moves slowly along, as we
advance on our way. Pretty soon, it will be
exactly opposite to us. Then presently it
will begin to pass along behind us, and finally
will get far astern. That changing of its
direction in consequence of our moving
along, while it is really at rest itself, is its
· parallar. Now, the way to determine how
far off any object is, when you cannot
measure directly, is by observing its parallax;
because the nearer to us the object is, the
greater will be its parallax.”
"I don't understand that exactly," said
Rollo.
"Why, the nearer it is," replied his father,
"the more rapidly it will appear to move
along when we are passing it. For instance,
if there was a man out on the water here,
with a lamp in his hand, only a quarter of a
mile from where we are, as soon as the lamp
came into view, we should see it appearing
to glide along very swiftly; and in a very
→
176
THE SKY.
:
few minutes, it would have passed out of
.sight astern."
"I wish there was one," said Rollo.
"So do I," replied his father; "but that
Cannot be. We cannot really witness that
experiment, but you can see that it must be
so, from the very nature of the case. So
you see that, if any object is at rest, at a dis-
tance from us, we can judge how far off it is,
by observing how fast it seems to move,
while we are going by it."
Rollo's father was mistaken in saying that
they could not have the opportunity to wit-
ness such a phenomenon as he had de-
scribed, for, just at the moment when he had
finished his explanation, a light suddenly
came into view, a short distance before them.
on the same side of the boat where they
were sitting, and it came gliding swiftly
along, so that it was almost opposite to them
before Rollo could recover from his surprise.
Why, father, what is that?" said he.
"I don't know," said his father.
some light very near, for it has a great paral-
lax; but I don't know what it can be. You
may go forward, Rollo, and see if you can
find zomebody to ask what it is."
"It is
PARALLAX.
177
Rollo came back in a few minutes, and
said that there was a man standing near the
wheel-house, who told him that it was a light
upon a vessel at anchor. The man told him,
he said. that all the vessels had to carry lights,
so that the steamboats might know where
they were, and not run against them.
By this time, the lighthouse had got con-
siderably astern, but it was yet distinctly in
view, while the light upon the vessel had
almost disappeared, as the steamboat had got
completely beyond it.
"Now, you understand something about
parallax," said Rollo's father. "The lan-
tern hung up on the vessel is nearest to us.
Next comes the light upon the lighthouse;
next the planet; and Sirius is farthest off
of all; and they all appear to change their
direction from us, more or less rapidly, ac-
cording to their distance. The vessel's lan-
tern, a few minutes ago, was directly before
us, and now it is almost directly behind. It
has changed its direction nearly a hundred
and eighty degrees in a few minutes. The
lighthouse has been moving slowly along,
and has not changed its direction more than
forty or fifty degrees, perhaps, all the time
178
THE SKY.
•
•
that we have been looking at it. The
planet is farther off still, and we cannot see
that it has changed its direction at all;
though it has changed its place a very littie;
and finally Sirius, which is most remote of
all, even if we were to observe it with the
very nicest instruments, would not scem to
have moved in the least degree."
29
"Yes, father, I understand," said Rollo.
"We can observe the parallax, very easily,'
said Rollo's father, "in the case of these
lights, and other things so near; but we can-
not perceive the parallax of the heavenly
bodies, without instruments and nice obser-
vations. The astronomers have such instru-
ments, and they note how much the heavenly
bodies change their direction from us, when
they are observed from different places, and
from that they can calculate the exact dis-
tance."
'I don't see how they can calculate the
exact distance," said Rollo.
"No," said his father, "I do not suppose
you can. You can only understand a very
little about such a subject. I only wanted to
give you some general idea of the way they
measure the distances of the heavenly bodies
PARALLAX.
179
It will be of some use to you sometimes, in
enabling you to form some judgment of the
distance of objects you see when you are
riding or sailing. Sailors can judge of the
distance of a mountain, when they are sailing
along the coast, by observing how fast it
seems to move along the horizon.'
Just at this moment, Rollo, who happened
to be looking at the lighthouse, observed
that it was beginning to move very swiftly
around towards the stern of the boat.
"Why, father," said he, "the lighthouse
is moving away very fast now."
"Yes," said his father; "I see it is chang-
ing very fast; but that cannot be parallax.
It must be because the boat is turning out of
its course. I presume we are turning to go
into the harbor.”
So Rollo and his father rose from their
seats, and walked forward, in order to be
able to see more distinctly what was going
on. They advanced along the promenade
deck towards the wheel-house, and took their
stand by the side of the wheel-house, near
the ladder which led down to the main deck
below.
4
180
THE SKY.
:
'.
!
•
There was a railing before them to keep
them from falling off.
The
They could see, before them, the dim form
of the land, with the outlines of the buildings
of a town relieved against the sky, and on
the water between them and the town, they
saw quite a number of lights which belonged
to vessels lying in the harbor. One vessel
was so near that they could see the dark
form of her hull floating on the water.
other lights were at different distances.
Rollo was very much interested in observing
the different degrees of rapidity with which
they appeared to move, as the steamboat
glided by them. He found that he could tell
very easily which were near, and which were
remote, by observing their apparent motion.
"Father," said Rollo, after watching these
lights a little while, "I can tell which
lights are nearer than the others, by their
moving quicker; but I cannot tell how far
off any of them are."
"No," replied his father; "I know you
cannot. It requires some nice measurements
and observations to do that."
"But I thought you said, father," rejoined
PARALLAX.
181
Rollo, "that they could tell how far off the
stars are, without measuring, by the par
allax."
"Yes," said his father; "that is, without
measuring the distance to the stars; but they
have to measure some other distances. For
example, if we were going to ascertain how
far off we were from that lighthouse half
an hour ago, it would be necessary to have
taken an observation of its direction from us
exactly, with an instrument. Then, after a
time, when we should have sailed a certain
distance, we should have to observe the direc
tion again, very carefully; and we must als>
note down very exactly the distance we had
sailed. Then we could make the calculation."
"How should we do it?" asked Rollo.
"O, you cannot understand that yet," said
his father. "In order to know how to make
such a calculation, it is necessary to under-
stand trigonometry."
"Is trigonometry hard?” asked Rollo.
66
No,” replied his father, "not if the pupil
is old enough to study it.'
Just at this moment, Rollo heard a little
snap in the wheel-house, and immediately
afterwards the bell rung in the engine-room
16
182
THE SKY.
1
..
and the engine stopped. He looked up, and
saw that the steamboat was just coming
up to the wharf. There were a great many
persons coming and going upon the decks of
the boat, and he could see a few persons also
upon the wharf. There was a lantern on
the wharf, upon a post, but it did not give
much light.
There was a man standing upon the fore-
castle, below Rollo and his father, who had
a coil of rope in his hands, which he was
preparing to throw on shore. He made, first,
a large coil with his rope, which he then
divided into two parts, holding one part in each
hand. A moment afterwards, he threw the
two coils, first the one in his right hand, and
then, immediately following it, the one in
his left. The end of the rope went away
over upon the wharf; and the man who was
standing there immediately seized it, and
began drawing it in.
"Come, father," said Rollo; "it is time for
us to go."
"Yes," replied his father; "I think it is."
So our two travellers walked back to the
part of the boat where there was a staircase
leading down to the main deck. They went

PARALLAX.
183
down the staircase, and came upon that part
of the deck which was in front of the en-
trance to the ladies' cabin. Here there were
a great many passengers collected, waiting
for the moment when they were to go on
shore. The little bell in the engine-room
was rung repeatedly, and the engine was
sometimes stopped, and sometimes set in
motion, until finally the boat was brought
up to the wharf, and secured there.
"Please to stand off the plank, gentlemen,
said one of the hands, who stood near the
place where they were to go off from the
deck of the steamboat to the wharf.
Rollo looked down, and saw upon the deck
of the boat a very wide plank. In fact, it
was formed of two planks fastened together,
side by side, so as to be wide enough for
two or three persons to walk over together.
It was made to be placed across from the
steamboat to the wharf, for the passengers to
walk over, when they wished to go ashore,
or to come on board the boat.
The gentlemen who had been standing
upon this plank stepped off from it when the
order was given, and then four men took
hold of it, one at each corner, and lifted it
184
THE SKY
up. It was so heavy that it required four
men to lift it easily. The men then threw
the plank forward in such a manner that it
fell with one end resting upon the wharf
and the other end on the deck of the boat.
Thus it formed a sort of bridge from the
boat to the land. The passengers immedi-
ately began to pour over the bridge in a
strong current, men, women, and children,
all crowding forward together; and thus
they all soon passed safely to land.
They found the train of cars all ready for
them, and the locomotive hissing upon the
track. The company crowded into the cars,
all anxious to get a good seat.
"Well, Rollo," said his father, when they
were at last fairly seated in the car,
66 'here
we are safe in the car; and I suppose you
are glad."
"Why, yes, sir," said Rollo; "but I am
not very glad, for I like to look at the lights
in the vessels."
16
Perhaps you can make observations of
the same kind on the shore," said his father.
"We may see some lights in the houses as
we pass along."
PARALLAX,
185
"I'll look," said Rollo, "and then I can
tell how far off the houses are."
CC
'Yes," said his father; "only now we are
going much faster than we were in the boat,
and that will make the parallax of any light
greater than it would be as seen from the
So you must make some allowance
for that."
poat.
"How much, sır?" asked Rollo.
"O, it is impossible to say how much,"
replied his father, "since I don't know how
much faster we go."
However, Rollo was prevented from mak-
ing any observations on parallax, while go-
ing along in the cars, for at first there were
no lights to be seen. It was so early in the
morning that nobody had got up; and by
the time the morning was so far advanced
that lights began to appear at the farm-house
windows, Rollo was fast asleep in the car,
with his head reclined against his father's
shoulder.
QUESTIONS.
Where were Rollo and his father when the conversation
occurred which is described in this chapter?
name of the star which they saw in the sky?
What is the
What other
16*
186
THE SKY.
heavenly body did they see near it, which resembled it in
appearance? What remarkable appearance did they ob
serve in the water? Where did they go, in order to have
a better opportunity to observe this appearance? What is
the name used by astronomers to denote the difference of
direction in which an object appears when seen from dif
ferent places? How did Rollo's father know that the light
which they saw in the horizon must be several miles off
What difference was there in the appearances presented by
the light on board the vessel? Why did the light on board
the vessel appear to move more rapidly? How did Rollo
judge of the comparative distances of the vessels anchored
in the harbor ? What is the meaning of the word asimal
muka &
-
•
187
CHAPTER XIV.
THE AURORA BOREALIS
ONE day, Rollo went out with his father
and Nathan to gather raspberries. They
went into the woods. It was at a consider-
able distance from the house where they
lived, that they expected to find the rasp
berries; and, when they reached the place,
the berries were not very thick, and so they
kept going on farther and farther, until at last
they got more than a mile and a half from
home.
Instead of coming home through the
woods, after they had done gathering their
raspberries, they concluded to go across a field,
and so come out into a road which would
lead them home. Rollo's father said that it
would not be much nearer, but that it would
be easier walking along a road.
After they had walked about half a mile,
they began to be pretty tired, and they had
still a mile farther to go. So Ro.lo asked
188
THE SKY.
his father to tell them a story, to beguile the
tediousness of the way. He said he could
not tell them a story very well, but he wouid
give them some information about the sky
if he could think of any thing which he haɑ
not explained to them before.
"Well, sir," said Rollo, "that will do al
most as well.”
"There are several distinct luminous ap
pearances, produced in the sky by means of
the atmosphere," said his father.
"What do you mean by luminous appear
ances?" asked Nathan.
66
Appearances of light," replied his father
"There is the twilight, the dawn, the Au
rora Borealis, and the halo. I will explain
them to you in order.
"The twilight is the reflection of the
sun's light in the atmosphere after the sun
himself has gone down. The rays shine up
into the atmosphere, over our heads, and in
the western part of the sky, and there they
are reflected so as to make it light. If there
are any clouds in the west, the sun's rays
shine upon them, and make them appear of
brilliant colors. This twilight is very usefu
to us; for, without it, it would become
THE AURORA BOREALIS.
.89
....
suddenly dark as soon as the sun went down,
It would be very inconvenient for people to
be left suddenly in the dark, every evening,
just at sunset.'
"Yes, sir," said Nathan, "I think it would.”
"The second luminous appearance pro-
duced in the atmosphere," continued his
father, "is the dawn. The dawn appears in
the east. It is caused by the rays of the
sun shining upon the atmosphere in the east
before the sun himself rises. If there are
any clouds in the eastern part of the sky,
they appear in bright colors, but not so
bright generally as the clouds in the west
at sunset.
(6
Why are they not so bright?" asked
Rollo.
"I don't know why," replied his father.
"I will ask some philosopher the next time
I see one. This light in the east is the
dawn; it indicates the approach of day. In
ancient times, it was called the Aurora.
"There is another Aurora, which appears
in the north; but it is not followed by day.
It is called the Aurora of the north.”
"The Aurora Borealis?" said Rollo.
"Yes" replied his father.
"Borealis

THE SKY.
190
means of the north, or northern. It is the
northern dawn, but it is not followed by
day. If we should get lost in the woods, and
have to spend the night there, and if we could
find a place where we could see the sky,
we should watch it very anxiously for signs
of the morning. At last, perhaps we should
see a faint blush of light spreading along the
horizon, and we should think it was the
dawn, and that the morning was soon to
come. But presently we should find the
light fading away again, and soon see it
disappear, showing that it was only a north-
ern dawn,—a cold, false light, shining from
icebergs and frozen seas, instead of the har-
binger of morning."
"Does the Aurora Borealis come from the
icebergs?" asked Rollo.
"It comes from the north, the region of
icebergs,” said his father; "but I do not
know what it is caused by. The twilight
and the dawn are caused by the rays of the
sun shining upon the atmosphere; but there
is no sun in the north to produce this kind
of dawning.
""
"Does any body know what makes it?"
asked Rollo.

HE AURORA BOREALIS.
191
"There
"I believe not," said his father.
have been a great many explanations offered,
but they are none of them satisfactory."
"What
Rollo.
are the explanations?" asked
"I don't understand them well enough
myself to attempt to explain them to you,"
replied his father. "So I will tell you about
halos. A halo is a luminous appearance
upon the clouds, or upon the vapors of the
atmosphere, around the sun or the moon.
Sometimes the halo is a bright circle. Some-
times there are bright spots at the quarters of
the circle. Sometimes it is in the form of
rays diverging from the sun in all directions.'
"I never saw a halo," said Nathan.
"I have," replied Rollo; "and I'll show
you one some day.”
Just at this time, Rollo observed that his
father was looking very intently at some
object at a distance before him on the road
It was a wagon coming.
Rollo observed that the horse looked very
much like his father's horse.
"1
"I wish it was our horse and wagon,'
said Rollo, "and then we could have a ride
home."

.92
THE SKY.
"It is," said Nathan; "I am certain it is
Jonas is in it, driving."
"Is it, father?" asked Rollo
"It may be,” replied his father.
..Jonas
was going to mill this afternoon, and this is
the road to mill."
It proved to be really Jonas. When he
came up, Rollo's father said he might turn
back, and carry them home. They accord-
ingly put their baskets of berries into the
wagon, and Jonas gave them a ride home;
after which Rollo and Nathan went with
him to mill.
QUESTIONS.
What is the meaning of the phrase luminous appearance ?
How many kinds of luminous appearances did Rollo's father
mention? What is the cause of the twilight? Of what
advantage is it to mankind? What
What is the cause of the
dawn? By what other name is it sometimes called?
What is the meaning of Aurora Borealis ?
What is a
ralo F
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