"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."