Part 8

"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?"