Rollo's Museum
g, as his father was sitting by the fire, with a book in his ha
busy now,-think
aid his
are not, I want to read you so
his lap, and Nathan opened his littl
the water, and w
ground, I could
t funny?"
nny," said
ad wings,"
said hi
en I cou
culties which prevent boys from flying. One is, they have no
d use them; I am pretty strong.
"but I do not think that you would be stron
I am stronger than
th than a bird, but not more in proportion to your s
mean by that?
r, and you are not as much stronger than he is, as you are larger. If you are a hundred times as heavy as he, you are not a hundred times as strong. That's what I mean by saying that you are absolutely
pole just above it; could you pull yourself up, from one pole to the other, by your hands alone, without touching your feet?-Or a ladder," continued his father,-"it will be better to supp
st commenced the conversation with Nathan, but who had been listening for a few minutes past to
I can. I have done
ould you go?"
er, the rounds are too far up. I can't reach up very well. I
nds of the ladder; only the air is not fixed, like the ladder, but constantly gives way under his wing; and so, to make the case the same, you must suppose that the ladder is not firm, but i
at their father was saying, but they both admitted
this is very hard. They must either have very large wings, and prodigious strength to use them, so as to pull upon the air with
the strokes; and those of humming-birds, which are smaller
he began to imitate the flapping of the wings of a bi
e same motions. "That is as fast as cr
hereas you only move hands and arms. If you had great wings, as lo
ould they be
haps as big as the to
s big as that. The crow's wings are not longer than hi
rger than it really is. I presume his wings, when they are spread, are twice or three times as long as his body. If you had wings in proportion, it woul
mselves up by the air," said Nathan. "I di
omething real,"
ithout moving their wi
ather, "and so ha
!" repea
one fly?" s
ou never see a stone fly through
Rollo, "when so
one in motion, it will continue in motion for so
w birds," said Nathan; and he
go on, as long as the impulse they have given them lasts. This shows what prodigious strength they have in their wings. They can not only strike the air hard and frequently enough to raise themselves u
d seen the swallows sailing swiftly round and round in the
ay of a boy's flying, is not the want of wings, but the want
t?" said
n the air, if there was the necessary power to work them. The great difficulty in almost all cases in mechanics is, in getting the power; there is very little difficulty in appl
rong enough to paddle themselves along
pon it. But air cannot support them; and, of course, a great part of the effort which they would make, would be required to
water is sometimes in rapid motion.
miles an hour, would be very hard to row against. But the air is seldom in a state of less motion than that. It is very often moving at the rate of f
h," said Rollo, "to float in
n it was calm," replied his fathe
ght enough to float i
I don't think of any vis
by visible subst
here are some other kinds of air, which are lighter than
louds. They float, and th
vier than air. And yet they seem to float. If they are large, like rain drops, they fall quickly to the ground. If they are small, like mist, they fall slowly. That I should expect. If they are finer still, like vapor or fog, I should think that they woul
rom the top of the c
ises; and the hot air from the top of the chimney carries the vapor up with it, no doubt. After it rises a little way, and becomes cool, it ceases to ascend, but floats away horizont
r a little time, they wou
e gradually dissolved, and disappear, and thus never reach the earth. I should think they would descend
ill float in the
descend, unless you put it out in the open air, where there are currents to carry it up. It descends very slowly, but still it descends. It is heavier tha
ther?" s
the earth, and float upwards, till they got up where the air
Rollo, "we sh
rm a perpetual cloud over our heads, to keep out the sun, and to make the world dark and gloomy. There seems to have been no
air, they sink in it, like stones or iron in water. Only those that are very
by expanded, fat
ittle different way. A feather is expanded, that is, it is spread out in fine filaments, which extend, in every direction, into the air,
anded in a soap b
descend slowly. Water is expanded, too, in clouds; for, in that case, it is divided into millions of small particles, by which it is spread out over a great deal of air, and ca
it?" sa
r the car, which the man is in. Then, if the balloon bursts, or any other accident happens to it, and the man begins to fall, the parachute opens and spreads, and
ollo, as they were playing in the yard,
there is one
said Nathan; "a
, what is the same thi
t the same?"
only a large umbrella; and father has got a large umbrella in the
t got any ballo
r for that,"
ing to get up into t
hed, and jump off that, and h
about the parachute. After describing to him the construction of it, and its use by men who go up in
igh place, and jump off, and hold the parachute over my
James, "I don't
ngs down a great deal of air with it, and this makes it come very slowly.
towards him, thinking tha
ned to make the first experiment from the low side of the shed. He could climb up, by means of a fence at the corner. James advised him, however, to try it first from the end
e but that he could jump off the house with it; and, at any rate, he could jump off the shed, he knew. He accordin
, as he had to put out both his hands, to save himself, when he reached the ground. As it was, he came down
yourself, Roll
d Rollo,
the umbrella di
bbing his elbows, "it didn't, and
st as hard as you
t broke his back; I don't believe
ttle. But it was not large enough to enable him to descend in safety. When his father said that a parachute was in fact only a large umbrella, he mean
STI
n more important than that of wings? Did Nathan think that a boy was stronger than a bird? Is a boy absolutely stronger than a bird? Is he relatively stronger? What is the meaning of relatively str
the earth's surface were light enough? What are clouds composed of? What difficulty did Rollo's father point o
to co