_Uncle Philip and the Boys make a Voyage, and he tells them
of an Animal that makes itself into a Ship; and of an Insect that
builds a Boat, and floats about in a Canoe; and of another that
pumps Water, and wears a Mask; and of a Spider that builds a Raft,
and floats upon it._
"Well, boys, I have a most delightful plan for us to-day."
"What is it, what is it, Uncle Philip?"
"Why, I have a little voyage to make, and my boat is on the river just
above the mill. I have the men there to row it, and every thing is
ready."
"Oh! dear Uncle Philip, this is charming! we shall be so happy!
But--but--"
"But what, boys?"
"Why, Uncle Philip, we have not asked leave at home. Now our parents are
very happy to have us visit you, and say that they are very much obliged
to you for telling us so many things; but they have told us, too, never
to get into a boat without asking their permission first. Uncle Philip,
we are sure they will let us go, if they know that you are going; only
let us run home and ask them."
"My dear boys, I am very much pleased with your conduct; and, what
is far better, my children, God is pleased; for he has commanded you
to honour your father and mother: but you need not go home to ask
permission, for you may depend upon it I would not take one of you upon
the water without the consent of your parents: so I went yesterday,
while you were all at school, and have got permission from your friends
for every one of you to go--only I asked them to tell you nothing about
it."
"Oh dear, Uncle Philip, you are so very, very good: thank you, thank
you, a thousand times over."
"Once is enough, boys. There is but one Being who deserves a thousand
thanks, and he, in truth, deserves a great many more than a thousand;
but I fear that from a great many he is just the Being who gets the
fewest,--it is our Heavenly Father: but come on, boys, let us be going
to the boat. We shall soon reach her. Ah, yonder she is; I see her
through the trees."
"Oh, what a beauty she is, Uncle Philip, with her green sides and white
belt near the top. We shall have a charming voyage."
"Come, then; get in, my little sailors, and seat yourselves yonder in
the stern. Now we are all ready; shove off, men, and use your oars. I
will take care of the helm."
"Oh, Uncle Philip, how smoothly we go along! this is charming. Is this
the way a ship goes, Uncle Philip?"
"A ship floats, boys, just as the boat does; but she is not rowed with
oars; she has sails, and the wind blowing upon them sends her along."
"Uncle Philip, there are no ships among animals, are there?"
"Oh no; but there is a very curious little animal which lives in the
water, and manages to rig out something like a ship, and to sail."
"What is it, Uncle Philip? pray let us hear of it."
"It is called the nautilus, and I saw a great many of them in the
Mediterranean sea. The shell is nearly round, and six or eight inches
across, not much thicker than paper, and of a whitish colour: it
has, too, a keel or ridge upon each side. When it wishes to sail, it
stretches upwards two of its legs: these have a very thin skin at the
end, which the nautilus spreads out for sails, and the other legs hang
over on each side of the shell for oars or rudders. When the sea is
calm, a great many of them may be seen playing about; but as soon as a
storm arises, or they are disturbed, they take in their sails and sink
to the bottom. But, boys, the most curious boat that I know, made by one
of the dumb creatures, is the work of the little insect that played the
doctor the other day, and stuck his lancet into us. Do you remember what
insect that was?"
"Oh yes, very well, Uncle Philip, it was the gnat."
"True, boys, it was the gnat, which is an insect that spends the first
part of its life in the water, and the latter part in the air. The grub
of the gnat lives in water, and I will give you the whole history of
this curious insect. We will first speak of the eggs, for out of these
it is that the boat is made. In order to see this boat made, you must
go early in the morning, between five and six o'clock, to a bucket, or
pond of stagnant water, where gnats are to be found: if you go later
you will not see it. The gnat's eggs are shaped something like a pocket
powder-flask, and it is by putting a great many of these together that
she makes the boat. To do this, the mother gnat stands by her fore-legs
upon the side of the bucket, or on a leaf or stick in the pond, and her
body is on a level with the water, and rests upon it, except the last
ring of her tail, which she raises a little. She then crosses her two
hind-legs in the shape of the letter X, and begins to put her eggs in
that part of the X nearest to her body. So she brings her legs, crossed
in this way, near to her body, and puts an egg in the angle, covered
with a kind of glue, which will make the eggs stick together. On each
side of the first egg she puts another in this shape .*., and here is a
drawing of the insect at this part of her work.
[Illustration: A Gnat making her Boat of Eggs.]
"She then goes on adding eggs, which are all put in the water with their
ends downwards, until she has got her boat half-finished; she then
uncrosses her legs, and just keeps one on each side of the boat as she
goes on, until she has completed it."
"And how many eggs, Uncle Philip, will she put together in this way?"
"From two hundred and fifty to three hundred and fifty, and when all are
laid they make quite a good boat, sharp, and raised at both ends, and
floating on the water. Then the mother gnat leaves it. Here is a picture
of one of these boats.
[Illustration]
"Now I will tell you of what becomes of the young ones in these eggs.
They come out of the lower part of the egg, and commonly swim, with
their heads downward, near to the top of the water."
"With their heads downward, Uncle Philip! what is that for?"
"Why, they have a tube at the end of their bodies, near the tail,
through which they breathe; and that part must, you know, be at the top
to get air. Besides this, its tail and its breathing tube both end in a
sort of funnel, made up of hairs placed somewhat in the form of a star,
and covered with oil, so as to keep off water, and these buoy or float
it up. When it wishes to sink, it just folds up its funnels, and shuts
up in them a little bubble of air, which it breathes under the water;
and when it wishes to rise, it opens its funnels, and they float it to
the top again. Here is a drawing which will show it to you.
[Illustration: Larva of the common Gnat floating in water, greatly
magnified. _aa_, the body and head of the larva; _b_, the respiratory
apparatus, situated in the tail; _c_, the larva, not magnified.]
"They are hatched in a few days, and then the boat of empty eggs floats
about until it is destroyed by the weather. And to show you how good a
boat it is, I will tell you what a gentleman did to prove it. Mr. Kirby,
who is very fond of natural history, and has written a great deal about
insects, says that he put half a dozen of these gnat-boats in a tumbler
half full of water, and then poured upon them a stream from the mouth of
a quart bottle, held up a foot above them, and he could not sink them.
More than that, the water would not stay in them. If you push one to the
bottom with your finger, it will come up to the top directly, and you
cannot see any water in it."
"Why, this is a noble boat, Uncle Philip, that will never sink."
"True, boys; but listen, and you will find that before it can use its
wings the gnat has to sail in another boat still, much more dangerous
than this is. After it is hatched, it has to pass through several shapes
before it gets to be such an insect as you see. Here is a picture which
will show you its different shapes.
[Illustration]
"The first is the same which you saw in the last picture, only in this
drawing the head is uppermost. But its last change, when it becomes
an insect with wings, is the most curious part of the whole. When it
is about to get its wings, and become a perfect gnat, it raises its
shoulders just above the top of the water, and its skin cracks, so that
the head of the gnat immediately comes through. The shoulders come next,
and make the crack larger; but it has yet all its body to get out, and
its legs and wings are as yet all shut up in its case. Now is the time
of danger for the gnat. It raises itself nearly straight out of the
crack, and by wriggling works its body along: and if a particle of water
should get upon the case, or touch its wings, it would be overset, and
must perish. Thousands and thousands die in this way. It is so very
light, too, that the wind will drive it about, and whirl it round and
round upon the top of the water; and when it is almost out, the insect
is tossed about in a canoe or boat of the very weakest sort, while its
body is a mast, which appears much too large for so small a boat. At
last it gets far enough out of the case to stretch its fore-legs, and
put them down upon the water (which will bear a gnat's weight), and then
it is safe; it spreads its wings, and soon leaves the little boat which
was so dangerous. Here is a picture of the gnat getting out of its case."
[Illustration]
"Well, Uncle Philip, all this is very strange; we never knew before that
the gnat was a sailor."
"I suppose that you did not, boys. But as we are talking of boats, pray
can you think of any way of making a boat move through water without
oars, or paddles, or sails, or something to pull it along?"
"No indeed.--Oh yes, Uncle Philip, by steam."
"Ah, I mentioned paddles, boys, and a steamboat is forced along by them."
"No; Uncle Philip, we do not know."
"Well, I will tell you then of another way in which I have no doubt a
boat might be made to move. If there were any contrivance by which a
large quantity of water could be kept in the boat, and if this water
were forced out of tubes or holes at one end very violently, it would
push against the water in which the boat was floating, and force her
along. Some years ago a plan was thought of to make a steam engine throw
the water out of the stern of the boat, and thus to force her along; and
before that, Dr. Franklin tried some schemes for the same purpose, but
they never succeeded. Now there is an insect which adopts precisely this
plan, and perhaps some of those who thought of it got the notion from
the insect."
"What insect is it, Uncle Philip?"
"It is the grub of the dragon-fly. If you catch one of these grubs and
put it into a saucer of water with some of the dead leaves or sticks
it had for a covering, you will see these leaves or sticks floating
towards the tail of the grub, and afterward driven off again. This is
because the insect is pumping in water, and then throwing it out. If you
take one of them out of the water, and hold it with its head down, and
let a drop of water fall upon its tail, it instantly sucks it in, and
you can see it grow larger; and when it throws it out again it becomes
smaller."
"But, Uncle Philip, how can you see it suck the water in?"
"Very easily, boys. When it is in the water, if you will colour some
other water with indigo, or ink, or any thing else, and then hold a
glass tube just over the tail of the insect, and very carefully put some
of the coloured water into the tube, you will soon see the grub spirt
out a stream of it to the distance of several inches: or if you will put
the insect in a saucer of coloured water, and then suddenly move it, and
put it into one of clean water, you will see it spirt out the coloured
stream plainer still."
"Why, Uncle Philip, it must have a pump inside of it."
"It has, boys, something very like one. This stream of water is forced
out to help the insect along; for though it has six feet, it uses
them very little except for catching food. It drives the water out so
strongly against the still water behind it, that it sends it forward,
with a dart, very rapidly. Here are two pictures; one shows the pump
open, and the other shows it shut."
[Illustration]
"Uncle Philip, is there any thing else curious about this insect?"
"There is, boys, something well worth attention; did you ever see a
mask?"
"Do you mean, Uncle Philip, a face made of pasteboard, very frightful
commonly, which you can wear over your own face?"
"That is a mask, boys; but so is any thing which is made to wear over
the face, and hide it. Now this little insect has a mask, not made
like a man's face, but which completely hides its mouth, and it is
exceedingly curious."
"How is it made, Uncle Philip?"
"Why, boys, I am not sure that I can tell you, so that you will
understand me; but I will try. Suppose your under-lip was horn, instead
of being flesh; and suppose it hung straight down until it reached the
bottom of your chin, so as to cover the whole of it, and that at the
bottom there was a large three-sided plate which was hollowed out, and
fastened by a joint or hinge to the bottom of your long lip, so that it
could turn up on the hinge and cover your face as high up as your nose,
and hide your long lip and your mouth and part of your cheeks: suppose,
too, that at the upper end of this long face-cover there were two other
pieces, so broad that they would cover all your nose and your temples,
and could open sidewise like jaws, and show your nose and mouth, so that
when they were opened they would appear like the blinders to a horse's
bridle; and then suppose that these jaws, upon their inner edges, were
cut into a great many sharp teeth, which fitted into each other, and you
will have some notion of this curious mask. Do you think you understand
me?"
"Why, pretty well, Uncle Philip, we think."
"Well, boys, here are some pictures, and with their help I hope what I
have been saying will be plain enough. In one picture the mask is shut;
and in the other, one of the jaws, like a blinder to a bridle, is open.
While the insect is at rest, it keeps the mask over its face; when it
wishes to use it, it unfolds it, and catches its food, and holds it to
its mouth. A gentleman once saw one of them holding and eating a large
tadpole."
[Illustration: Mask of the Dragon-fly, shut and open.]
"Uncle Philip, this mask is any thing but handsome."
"Very true; but you know we agreed when we were talking about the bats
to look at animals even if they were not handsome. And there is your
poor little ugly insect that you thought it right to kill, the spider;
did you know that the spider was a sailor, too?"
"No, indeed, Uncle Philip! Pray tell us of it, will you?"
"Yes; but wait a little, until we bring the boat's head right, for we
are near the landing-place. So--now, boys, I am ready. There is a very
large spider, about which not much is yet known, which actually builds
a _raft_, for the purpose of getting its food more easily. You may see
it sailing about upon the water, on a ball of weeds about three inches
across, which is held together probably by small silk cords spun from
itself; and the moment it sees an insect drowning, it leaves the raft,
gets the insect, and then returns to eat it at leisure. If you frighten
it, or it thinks danger is near, in an instant it is under the raft out
of sight."
"Ah, this is a cunning spider, Uncle Philip."
"Not half so cunning, boys, as the one we talked of which built a door
to its house. But here we are at land. Jump ashore, my lads, and give my
respects to your fathers and mothers, when you get home."
"We will. Good day, Uncle Philip."
"Good day, boys. I shall be glad to see you next Saturday."