Chapter IV: Part 4

"I dare say I do. There are persons much older than you are who have never attended at all to the doings of insects, who would be very much astonished by the history of the legionary ants; and probably would laugh at the whole account as an idle story; and yet it is all true, and those who have read and seen, know it to be true; and they know, too, that to deny it shows nothing but ignorance. However, I always let such persons alone. I can do them no good; for they are apt to be very conceited, and will not be convinced. And now for the legionary ant. This is a fighting ant, as well as the last I mentioned; and it actually steals the young of another kind, rears them, and puts all the work on them, so as to be idle itself. This curious fact was first found out by Mr. Huber; another gentleman, named Latreille, afterward saw the same thing; and now a great many naturalists know it, because they have sought for and seen it. The ant which it steals is of a dark ash colour; the legionary is of light colour. The dark-coloured ant is now called the negro ant, and is a very industrious, peaceable insect, without any sting. The legionary is a strong, brave ant, with a sting, but very lazy. I shall relate to you the account which Mr. Huber gives of the legionary. He was walking near the city of Geneva during an afternoon in the summer of 1804, when he saw quite an army of these legionary ants crossing the road; they passed through a thick hedge, entered a pasture, and kept on through the grass without separating; and Mr. Huber followed them until he saw them come near a nest of negro ants. Some of these negro ants seemed to be guarding the holes into their nest; but as soon as they saw the legionaries, they, with a great many more from the inside of the nest, attacked the thieves. The legionary ants, however, were too powerful for them, and after a short but severe fight they conquered the negroes, who ran into the lower part of their nests. The legionaries then mounted their ant-hill, some entered it by the holes already made, and others began with their teeth to break other holes, so that all the army might get into the hill. They went in and remained but a few minutes, when they came out, each one having in his mouth a young negro ant, and off they scampered, without any order among them, every one going his own way, until Mr. Huber lost sight of them. The next day he set out to go back and examine further, and on his way he found a large ant-hill full of legionaries, and saw an army start from it, which he followed. They made the attack as before, and each one came off with a young negro ant in his mouth, and on going back to their hill, from which Mr. Huber saw them start, he had an opportunity of seeing them return, and was very much surprised to find all around the nest of the legionaries a great many full-grown negro ants. At first he thought that perhaps they had gone there to fight the legionaries, but he soon saw that instead of fighting, the negro ants went out to meet the legionaries returning, and would caress them, and give them food, and finally take the young negro ants and carry them within the nest."

"But, Uncle Philip, why do the legionaries always take the young ones?"

"Because, boys, they know, I suppose, that the old ants would never be satisfied to remove from their homes; and therefore they take the young. These legionaries could work if they would, I think, but they depend upon the negro ants for house and home, and food too; and nothing can be more faithful and affectionate than these poor slaves are. To try them, Mr. Huber took thirty of the legionaries, and put them with some of the larvæ, or grubs of their own young, into a glass box with a thick coat of earth at the bottom of it, and he put honey also in the box, that they might not want food. At first the legionaries paid a little attention to their young; but they soon stopped; and they neither tried to make a house, nor took any food, so that in two days half of them died. Mr. Huber then put in _one_ negro ant, and this little creature set to work alone, made a chamber of the earth in the box, gathered the young together, fed the old, and put every thing into complete order.

"At another time Mr. Huber broke one of the ant-hills of these legionaries, to see how they would act, and in doing it, he, of course, altered their galleries and chambers. The legionaries seemed to be lost, and went wandering about, without knowing where to go; but the negro ants appeared to understand very well where they were: they could find such of the galleries as were not broken, and would take up the legionaries in their mouths and carry them into them. If the negro sometimes seemed for a short time to be lost, and not to know where it was, it laid down its master, ran round and examined until it knew, and then would come back, and pick up the legionary ant, and carry it off. In one case Mr. Huber saw that the entrance to a gallery was stopped up by a small lump of earth; the negro ant laid his master down, took away the piece of earth, and then carried him in."

"Why, these poor negro ants are sensible as well as faithful, Uncle Philip."

"Yes, boys, they are so; and I think it is likely that both kinds depend in some way upon each other, but we have not yet found all about it. I expect that in some things the legionary does for the negro ant what it could not do for itself. God has made them necessary to each other, and this is the reason they live together so kindly.

"But I think it is time now to leave the ants, and go back to our business of seeking for something like man's inventions and tools among the lower animals. Perhaps hereafter I may tell you more about ants; but at present I must bid you good morning."

"Good morning, Uncle Philip."

CONVERSATION XIII.

_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.

"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.

"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.

"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.

"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."

"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."

"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."

"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."

CONVERSATION XIV.

_Uncle Philip tells the Boys about an Insect with Tweezers,
and another with Pincers; and shows them how a Fly's Foot is made,
so as to stick to the Wall._

"How do you do, Uncle Philip, this morning?"

"Very well, boys, I thank you. You are all well, I suppose, or I should not see you here."

"Yes, we are all well, thank you, Uncle Philip. But one of us would be very glad to have your help."

"Why, what is the matter?"

"Charles Walker has run a splinter into his hand, and he wishes you to get it out for him."

"Oh, certainly, I will do that, if I can. Let me see: but stay--I must first put on my spectacles. Ah, now I see it; I can get it out, but I must take my tweezers to it. There, it is out."

"Uncle Philip, those tweezers are very useful. If you had not had them, you could not have taken hold of the splinter with your fingers; and what would you have done then?"

"Tried to cut it out with the point of my penknife; but the tweezers are better for such work; and that reminds me, boys, to tell you that there are insects with tweezers."

"Why, what tool is it that you cannot find among them, Uncle Philip? It really seems as if you found almost every kind among the lower animals."

"Oh, no--no, boys. There are a great many which I cannot find; but there are several, too, which, as you know, we have discovered."

"And, Uncle Philip, we suppose that men learned to make their tools and work at many of their trades from these dumb creatures."

"Stay, boys--I never said that, because I think that it is not true. We know that in some things men did not learn from the insects, though they might have done so. There is paper, for instance. How could men learn to make it from the wasps, when it was a thins: in common use a long time before Mr. Reaumur, of whom I told you, found out how the wasp made it? So, too, with a great many tools; men invented them, and afterward, perhaps, it was found out that insects had instruments like them: and at other times the insects did show men how to make some things. I will tell you of one which I think of just now. The city of London, in England, is on the river Thames. Some time since a plan was adopted to make what is called a tunnel under the river. This tunnel is a road dug out of the earth, under the bottom of the river, across it; and of course to keep the water from pressing in the earth as fast as it was hollowed out, it was propped up by walls built on each side, with a very strong arch at the top. The work has now stopped; but about half of it was made. In building this arched road under the water, the workmen used what they called a shield, to keep the water from coming through upon them: and the gentleman who invented it, says that he first thought of it, from examining a little animal named Taret, which will bore holes in large pieces of timber under the water. This little animal has upon its head a kind of shield, by which it keeps off the force of the water, and works without being disturbed. So here was a case in which the insect taught the man."

"Uncle Philip, that gentleman was a sensible man, in the first place to watch the Taret and examine its head, and in the next place not to be too proud to learn from it. I expect he was a naturalist; was he, Uncle Philip?"

"I do not know, boys; but I should think his discovery of the shield would make him an attentive observer, if he was not so before."

"Now, Uncle Philip, will you tell us of the tweezers?"

"Very willingly, boys. This instrument or tool belongs to the moths which you see flying about at times. The tails are covered with a down, which grows in the form of a thick brush or tuft, and has a shining silky gloss, different in colour from the short hair upon the rest of the body. The moth pulls off this hair to cover its eggs, and the tweezers are used for that purpose. Here is a picture of the moths."

"Uncle Philip, you said that the moth pulled this hair off to cover its eggs; are they easily frozen?"

"Not very easily, boys; but you are mistaken in thinking that the moth covers these eggs to keep off the cold; for as she lays them in July and August, and covers them at that time, it cannot be to keep off the cold."

"What is it for, then, Uncle Philip?"

"To keep off the summer heat, boys."

"Why, Uncle Philip! who ever heard of covering a thing up in hair or wool to keep off heat?"

"I have heard of it, and seen it too, boys. It may seem strange, but it is true, that down and wool, and such things, are nearly as good to protect an animal from very great outward heat as they are to keep off very severe cold. When I was at Naples, in Italy, it was summer;--the climate is a very warm one.--The country people were in the habit of bringing snow into the city from Mount Vesuvius, and every morning I could see them coming in with their snow, which they sell to the rich to use for cooling things: and they kept it from melting with straw and wool. And in our own country, especially at the south, it is very common when a large lump of ice is brought to the house to be used through the day in midsummer, to wrap it up in a thick blanket until it is wanted.

"But I have not yet told you of the tweezers. The moth has no jaws, like bees and wasps, so that it cannot pull off these hairs as the bee would; but, as I told you, it performs the work with its tweezers, which are placed in its tail, and are like the points of a pair of sugar-tongs. The insects, too, will use them very rapidly, and pull off a little of the down, spread the egg upon it, and then cover it with more down, and smooth it very neatly. Here are pictures of these tweezers."

"This is a curious instrument for the insect to have, Uncle Philip."

"True, boys, but a very useful one. I will tell you, however, of another strange thing concerning moths with their tweezers; I mean the way in which they will sometimes place their eggs. The kind of moth that does this work is not exactly known, but naturalists think that the eggs are moth's eggs, because they are covered with the down, exactly like those which are known to be moth's eggs. These eggs are twisted round a branch, like the thread of a screw, or like the curled end of a corkscrew put over a small stick. Here is a picture of some of these eggs."

"Ah, this is wonderful work indeed for a moth, Uncle Philip."

"As you seem to like this, boys, I will just mention to you that there is another moth, called the lackey-moth, which winds its eggs also around a branch. They are hard, however, and not covered with any down, and are put on in the strongest possible way. If men wish to make an arch of stone, you know that the stones will be more narrow at the bottom than at the top, so that the bottom of the arch may make a small circle, and the top a larger one: thus--

Now the moth goes on this principle. Its eggs are shaped like the bowl of a wine-glass, and the smaller end is put next to the branch. They are all glued together, too, with a kind of gum, which will not dissolve or melt in water; so that the rain cannot injure them. Here is a picture of these eggs.

"There is another insect, boys, which has something like tweezers; though I think they resemble pincers most."

"What is it, Uncle Philip?"

"The boys call it father long-legs, and I dare say you have often seen it. It is the crane-fly, and its pincers are used for putting its egg in the hole it has made for it."

"Where does it put its eggs, Uncle Philip?"

"In the earth, boys; and to enable the insect to do this, the female has the pincers I spoke of: they are made of something like horn, and are sharp at the point. With these she first bores a hole in the ground, and then puts the egg in. The egg is like a grain of gunpowder, and she puts herself in a very curious posture to bore the hole. Here, boys, you may see a picture of the pincers as they appear through a microscope, for they are not near as large as the picture. And here is a drawing of one boring."

"What good pincers those are, Uncle Philip: but will you tell us one thing which we wish to know? Talking about the crane-fly has put me in mind of it: the other day we were sitting together in school, and the wall over our heads was covered with common flies; and when we came out, we were talking about the way in which the fly stuck to the wall without falling down; and as we could not tell what kept him up, we agreed to ask you about it."

"I will tell you, boys, very willingly. I do not wonder that you were unable to tell how the fly stuck to the wall; for you never tried to find out, and therefore could only guess at it."

"And that is not a good way to find out any thing, Uncle Philip?"

"No, boys; though some persons much older than you are, did nothing but guess about this very thing, and guessed very far from the truth too. Some thought that the fly had a sponge in its foot, and squeezed a sort of glue out of it which made it stick fast; others said that the glass or wall was so rough that the fly's feet would catch hold of the little points upon it; but both were wrong."

"How does it hold on, Uncle Philip?"

"Did you ever see what the boys call a sucker, made of a piece of soft sole leather? That will show you how the fly's foot sticks fast. This leather is cut round, and has a string through the centre; the boys wet it, and then put it upon a board or something smooth, and stamp on it, and try to raise it up from the board by the string; and it requires some strength to pull it up: sometimes they put it on a small smooth stone, and then lift up the stone by it. The reason why the leather sticks so fast is because the air is pressing on it upon the outside, and there is very little or no air between it and the board, to press the other way."

"Why, Uncle Philip, is the air heavy?"

"Oh yes, boys, when there is so much of it as there is above the earth, it presses down very heavily. Now the fly's foot is like the sucker; when he puts it down he has a contrivance to drive out the air from under it, so that there will be little or none between it and the wall; and then the outer air presses upon it, and holds it fast."

"But, Uncle Philip, how does he get it up again?"

"Why, boys, by another contrivance, he can let air in under his foot again, and then he can easily move it; for we do not feel the weight of air when it presses upon both sides of us. The reason why you stand up straight is because the air is pressing all around you; if it were on one side of you only, it would press you down on the other side. Here is a picture of the fly's foot, as it appears through the microscope. You will see it has three suckers with the edges all like saws; these are to make it stick the closer. This picture, boys, is sixty-four hundred times as large as the fly's foot is."

"But, Uncle Philip, there is one thing yet hard to understand."

"What is it?"

"Why, the fly walks on the wall over our heads; now the air cannot press down upon his feet there."

"Very true, boys: it cannot press _down_, but it can and does press _up_ against his feet; for the air presses up and down and sidewise all alike."

"Ah, now it is plain enough, and we are much obliged to you, Uncle Philip, for telling us what we wished to know."

"You are quite welcome, my dear boys, to all that I can teach you: if it makes you to be wiser and better men when you grow up, I shall be very thankful to God that I have been able to do you any good."

"Good morning, Uncle Philip."

"Good day, boys; I shall expect to see you all in church to-morrow."

"We shall be there, Uncle Philip."

CONVERSATION XV.

_Uncle Philip tells the Boys how Hats are made; and then talks
to them about Animals that can make Felt like the Hatter._

"Boys, do you remember my telling you of a remarkable bird, called the tailor-bird, which sews very neatly?"

"Oh yes, Uncle Philip; it is not easy to forget such an excellent little workman; but why do you ask--have you any thing more to tell us about that bird?"

"No, boys, not any thing of that bird; but I was thinking last night of the work done by several other kinds of birds, some of them quite as good workmen as our little tailor; and I thought that, perhaps, you might like to hear of them."

"We would, Uncle Philip, be very happy to hear of them, if you will have the kindness to tell us about them. But what kind of work is it they do?"

"Various kinds, boys. There are some which make what is called _felt_, just as the hat-maker does; and some are weavers, others basket-makers; some build platforms to live on; and I assure you some birds' nests are as curious as any of the things of which I have yet told you."

"Pray let us hear of them, Uncle Philip."

"Very well, you shall. I will begin with birds that make felt like the hatter. Do you know how a hat is made?"

"Not exactly, Uncle Philip; but we know what it is made of."

"What is it, boys?"

"Of sheep's wool, and the hair of other animals: is it not?"

"Yes, commonly of these things; and to understand what I am going to tell you, I think it will be necessary first to say something about the hatter's trade. The business of the man who makes a hat is to mix up wool or hair in such a way that it will stick together and make felt; or something like a piece of thick, strong cloth. To do this, he does not weave the hairs together, for they are of different kinds, and of different lengths, and it would be endless work to weave every one in; besides the cloth or felt would not be thick enough when it was done."

"How do they stick together then, Uncle Philip?"

"Why, boys, their sticking together is owing to something in the hairs themselves. I will show you. Pull a hair out of your head; now hold it just between the ends of your two fore-fingers, and rub the fingers gently against each other."

"Why, Uncle Philip! see, the hair is moving towards my body."

"Very true; and if you will turn it with the other end towards you, and rub your fingers as before, you will see it move from your body."

"This is very strange, Uncle Philip: the hair is smooth; how can my fingers make it move so?"

"No, that is a mistake, boys, the hair is not smooth. If some kinds of coarse hair are seen through the microscope, each one will seem to be, not one hair, but ten or twelve smaller ones, which are joined at the root, and form a hollow tube, like a straw; and sometimes it will have joints just like some kinds of grass or straw. In some sorts of finer hair you cannot see this even with the microscope; but you can feel it, as you did just now when you moved your fingers. These joints overlap one another, just as if you should take several pieces of straw and stick them into each other. I will show you some pictures of hairs as seen through the microscope, and then these joints will be plain enough."

"These are strange-looking hairs, Uncle Philip."

"Yes, they are curious; but now you may see why, when hairs are worked together, they may be made to stick to each other. These rough parts catch into each other, and hook themselves; and the more you press them or move them, the more closely you work them into one solid mass, which you cannot easily pull to pieces. Besides, you must remember that the hairs will work only one way, as you found out just now when your finger ends caught upon the little joints and moved them along. Now, suppose that a very large heap of hairs, or wool, or fur, after it is made ready, should be put upon a table, and covered with a linen cloth, and pressed down in different directions. Each hair would begin to move in the direction of its root, just as it did between your fingers, and so all would be joined together at last into one solid piece."

"We understand you, Uncle Philip."

"Then you understand, boys, the way in which a hat is made. These hairs are all worked together by the hands of the hat-maker, and to make them work more easily (for curled hair, such as wool, does not move easily) the hatter uses hot water, and dips his hat in it while he is working it. After it is done, it is died, and then put upon a wooden block to give it shape, and is ironed smooth."

"And this is the way, then, Uncle Philip, to make hats: it is curious, is it not?"

"Yes, boys; but plain enough when you come to examine into it. And the best stuff for the hatters is such hair as has most joints ready to catch into each other: the rabbit's hair is very good, and for that reason."

"And is it possible, Uncle Philip, that any bird can do such work as this?"

"Not only possible, boys, but true. There are several birds very expert at making felt, and their nest appears like a piece of hatter's felt, or double-milled woollen cloth. I do not mean to say that it is as close and solid as the hat or cloth; it would feel in your fingers looser than either, still it is quite close; and when you examine it, you will find it put together in the same way; it is all carded into one mass, and not woven together thread by thread, or hair by hair."

"And are there many birds able to do such work, Uncle Philip?"

"I told you, boys, that there were several. The chief article which they use is wool, but with this many other things will be found mixed--sometimes, upon the outside, fine moss--sometimes pieces of a spider's web rolled up into a little bundle--sometimes, when cotton can be had, they will use small bunches of cotton-wool; but sheep's wool they must have, and by means of that, they contrive to make, with the other things I have mentioned, a felt wonderfully smooth."

"Is it smooth on the outside, Uncle Philip?"

"Sometimes quite so; but always as smooth on the inside, when it is first made, as if it had been felted together by the hat-maker. There is another thing curious enough in some of these nests. The hatter, you know, binds the rim of his hat to make it stronger; and some of these felt-making birds will make their nests stronger by a binding all around them of dry grass stems, and sometimes of slender roots, and they take care to cover these grass stems, or roots, with their felt-work of moss and wool. But there is something else not less strange, I think, than the binding. It is this: they will build their nests in the fork of a shrub or tree; and to keep them from falling, they will work bands of this felt round all the branches which touch the nest, both below and at the sides. And those parts of the nest which touch the large branches are always thinner than the other parts, which have no support; in those parts the nest is nothing but a thin wall of felt, fixed around to fit the shape of the branch, and that is enough to make that part of the nest warm and soft. Here is a picture of one of these felt-nests, fastened in the way of which I have been telling you."

"This, boys, is the nest of the chaffinch. The goldfinch makes a nest of the same kind, only rather neater and smoother than that of the chaffinch; for it takes pains to show nothing but the wool, and covers up all the other materials which it uses."

"Uncle Philip, do these birds all use the same things to make their nests?"

"All use wool, boys; but the truth is, that birds will commonly take for their nests that article which they can get most easily, if it will suit. A gentleman, named Bolton, tried this with some goldfinches. He saw a pair of these birds beginning to build in his garden; they had laid the foundation of their nest with moss, and grass, and such things, as they commonly use: he scattered some wool about in different parts of the garden; the birds took the wool: afterward he scattered cotton; they took the cotton: on the next day he gave them some very fine down; they took that, and finished the nest with it, and a very handsome nest it was."

"How long were they in making it, Uncle Philip?"

"Three days. The canary-bird, boys, which you sometimes see in cages, when free, builds a nest of the same kind. But the most curious felt-makers among the birds, are in Africa. There is the Cape-tit, a bird in the southern part of Africa, which builds a very strange nest: it is shaped like a bottle of India-rubber, as thick as a coarse worsted stocking, and made of cotton, and down, and other things felted together. On one side of the nest there is something like a pocket, and here is a picture of it."

"Uncle Philip, what is that pocket for?"

"Why, boys, some have supposed that it was for the male bird to sit on and keep watch, while the female was inside of the nest sitting on the eggs; but I think this is a mistake. And some have said, that when the female leaves the nest, and the male wishes to go too, he sits in this pocket, and beats against the side of the nest with his wing until he has made the edges of the top meet, and thus shuts up the mouth of the nest, and keeps off insects and other animals that would eat the young ones; but I do not believe this story."

"Then what do you think the pocket is for. Uncle Philip?"

"I think, boys, that it is nothing but a perch, or place for the bird to sit on before going into the nest. If the bird had no such place for stopping, it might be troubled to get into its nest. The mouth is small, and the bird could not enter it with its wings spread; and if it should alight on the edge of the nest constantly, it would injure it, for it is but slightly made. And I will tell you another reason why I think this is the use of the pocket. There is another bird in South Africa, called the pinc-pinc, which is the same species of bird as the Cape-tit; and this bird we know uses its little nest built upon the side of the other merely as a resting-place before going into the nest."

"Uncle Philip, does the pinc-pinc build its nest like a bottle, as the Cape-tit does?"

"No, boys, not so smooth, but felted in the same way. The nest is made mostly of the down of plants, and is either snowy white or brownish, according to the colour of the down. On the outside it is a clumsy-looking thing, but fastened, like the nest of the chaffinch, very firmly to the branches near it, so that you cannot take it away without breaking it to pieces. But rough as the outside is, you would be astonished, if you were to look at the inside, and see how a bird, and a small one too, with nothing but its wings, and tail, and feet, and bill for tools, could ever have worked the down of plants together, so as to make of it a piece of fine cloth. It has a narrow neck, something like a chimney, at the top of it. This is the entrance; and at the lower end of it there is a lump, which appears something like a small nest stuck on to the larger one; sometimes there will be three or four of these small-looking nests, and sometimes when there is a branch near the mouth of the nest which makes a good resting-place, there will be none. Here is a picture, boys, of the outside of one of these nests.

These birds are easily watched; and a French gentleman, who has written the best account of the birds of Africa,[11] says that he has found at least a hundred of these nests, and watched the birds for a whole morning together, and never saw one sitting on the small nest as a watch-bird; but has seen both the male and female arrive at the nest together, perch upon the nearest branch, hop from this upon the edge of the little nest, and then putting their heads into the hole, dart into the large nest. And now, boys, what do you think about the use of these little pockets?"

"Oh, Uncle Philip, we think that what you tell us is always right, because you know a great deal more than we do."

"But, boys, you do not understand me. I may be mistaken, though I do know more than you. I have been telling you my reasons for thinking these little pockets are nothing but perches. Do you think the reasons are good ones?"

"Why, yes, Uncle Philip, we do. The French gentleman who watched the birds so much would have seen some of them using the pockets for a place to keep watch in, if they were made for that."

"Right, boys. What I wish to teach you is to think for yourselves. Whenever any one gives you a reason for a thing, just ask yourselves, 'Is this a good reason?'"

"But, Uncle Philip, how did it happen that the other people who saw these birds should have said that these pockets were for the male bird to sit in and watch?"

"I suppose, boys, that they really thought so; but then they had not noticed the birds enough to find out the truth. It requires a great deal of time and patience to find out the truth about animals: and this is the reason why so many mistakes have been printed about them. It is a pity that such mistakes have been made; for really there is enough that is very curious about them, without men's making stories to appear strange. But I think that there will be fewer mistakes made in future."

"Why so, Uncle Philip?"

"Because, boys, men are taking more pains to see for themselves. There are more naturalists now than there were formerly; and I hope there will be more still, especially in our own large and beautiful country, where there have not yet been many. I hope that natural history will be studied in all our schools before a great while. But let us go back to our African birds.