"Uncle Philip, we saw a very strange thing just now; as we were coming, we saw a great many bees flying by us, and each one was carrying a little stone."

"That was strange, indeed. Did you find out any thing about them?"

"We asked a man who was near what they did it for, and he said that they carried the stones to prevent the wind, which is blowing pretty fresh, from tossing them about too much."

"That is a very silly story, boys, though it is a very old one: for I have seen them carrying what you call stones when it was quite calm, and there was no wind to blow them away. The man was very ignorant, or he would have told you another story, which would have been both strange and true."

"Will you have the goodness, Uncle Philip, to tell us what it meant?"

"Very willingly, boys. What you saw I presume were bees. You remember that I told you there were several kinds of bees; and this one is called the mason-bee. This kind builds his nest of mortar, and was therefore called the mason-bee by Mr. Reaumur first, I believe."

"Where does it get the mortar, Uncle Philip?"

"It makes it, boys. This kind of bee may be seen flying about, picking up sand, grain by grain, putting it into a heap, gluing them together with a sort of gum out of her own mouth, and building with them a foundation for her house. This little workman commonly builds against the side of a wall between two bricks where the mortar has fallen out; and if you should see one of the nests, it appears exactly like a lump of dry mud which has been thrown wet upon the wall out of a cart-rut: but when you examine it closely, you may see a great many small stones in it, more than is common in mud: a hundred people, though, might pass by it, and never think it was any thing more than a lump of dirt, which had been thrown upon the wall when it was wet, and had afterward dried there. Here is a picture of one of these nests.

You see there is a small hole in it; this leads to a cell inside about an inch deep, and shaped exactly like a lady's thimble; the inside of this cell is polished smooth, and appears like a wall of plaster, except that it has little yellow stains upon it. Here is the bee that makes it.

In making this mortar to build with, the bee will sometimes add earth that is soft to its grains of sand, and when the lump is about the size of a small shot, it takes it up and flies away with it, to work it into the wall."

"Does it always use sand, Uncle Philip?"

"Not always: sometimes it takes wet clay, and will dig into a bank of clay baked hard by the sun on the outside, so as to get that which is wet.

"Mr. Rennie, a gentleman in England who is very fond of watching insects, and has found out a great many curious things about them, has given an account of some of these bees which he noticed at work. Every one was carrying out of a hole in the clay-bank a small lump of clay; and on catching one of them, he found that this lump was wetter than the clay in the hole, so that the bee had moistened it, and worked it together, to make it stick like good mortar. These lumps too were larger than a shot; they were as large as a garden-pea."

"How long did it take them to work up the lump?"

"About half a minute, Mr. Rennie says. He watched one of these little creatures, and found that she was building on the inside wall of a coal-house, where the bricks and mortar were left rough: she was at work between two of the bricks where the mortar had fallen out, or where the bee had taken it out. And the conduct of the bee at her house was very different from what it was at the clay-bank. She was not frightened, but went on working when any one came near the clay-bank; but at her house she seemed afraid that it should be found out where it was. She would alight first on the roof outside, as if she merely wished to rest herself; and when she flew into the coal-house she would not go directly to her nest, but would settle on a shelf, and sometimes pretend to be examining a great many places in the wall between different bricks; and at last, when she supposed there was no risk, or when there was nothing to alarm her, she would fly to her nest, and go to work with all her might in fixing her piece of clay to the wall."

"Why did she wish her house not to be found out, Uncle Philip?"

"Mr. Rennie supposed it was her instinct: she had seen probably some of the insects which would destroy her young, watching her to see where she was building; and sometimes after flying nearly to her nest with a load, she would turn back and fly towards the clay-bank, or take a large sweep off in another direction, and so come to her house.

"Besides the mason-bee, boys, there is the mason-wasp, which I have heard some persons call the dirt-dauber: it is very common, especially in the southern part of the United States. It works very much like the mason-bee, only it is apt to fix its nest under the eaves of old houses, which I think the mason-bee never does.

"There is also another kind of mason-wasp which will actually break a hard brick. Mr. Rennie says that he saw one at work on a brick of a hard yellow kind. Whether the wasp found a hole in the brick to begin with, he did not know; but if he did he was hard at work making it larger: he would break off a piece as large as a mustard-seed at a time. Here is a drawing of that kind of wasp; and the insect is no larger than the picture.

It seems wonderful that so small an insect should have so much strength. Here is a picture of its jaws, seen through a microscope, so as to appear a great deal larger than they really are.

"I do not know, boys, that the masons we have been talking of, show us any tools like those with which men who are masons work; but they show us, at any rate, how to make mortar by kneading or working it together; and they certainly show us that we were not the first who built walls. But there is another kind of mason who works in stone. He picks out the stones which are of proper size, and he fastens them together with mortar really as men do."

"Pray tell us of him, Uncle Philip."

"I will. The insect I mean is the caddis-worm, which is to be found sometimes in ponds, and very often in springs of fresh water. There are several sorts of them, but the one I am thinking of now, builds a stone house to live in. These worms are in the habit of making a little tube, sometimes of sand, or shell, or wood, or leaves, or stones, to live in; and their skill consists in joining these perfectly, and making them stick together. But we are talking now of the caddis-worm that uses stone. What the worm has to do is to make a tube out of small stones, that shall have a hollow about as large as a wheat straw, and be perfectly smooth inside. This is a pretty hard task—at least it would be very hard to us. When the stone-mason wishes a stone of a particular size or shape, and cannot find it, he takes his hammer and breaks one until it will suit; but the caddis-worm has no hammer, and must take the stones just as it finds them. The little insect then has to pick out a great many stones before he gets the right one, because they have so many little rough points about them that it is very difficult to get those which will make the tube perfectly smooth inside. Remember, too, that the bottom or lower side of this stone case has to be pretty nearly smooth, so that the worm can drag it along on the bottom of the spring or pond (for it never comes out of it), and you will see that the picking out of the stones alone is no trifle. But besides this, it has to fasten them together with mortar."

"And can the worm really do this, Uncle Philip? Will not the water wash the mortar all away?"

"It certainly would if it were like common mortar. It was a long time that men lived before they found out a mortar that would remain, and grow hard under water. When they want to build a wall that is to be under the water, they use a cement which is called pozzolana; it is made of lava out of a volcano, and is water-proof. Our caddis-worm has a cement too, which is better than pozzolana, and though it has been tried, it cannot be melted or dissolved in water. Here is a drawing of the stone nest of a caddis-worm."

"Uncle Philip, you said that sometimes these worms built their nests of other things besides stones; let us hear something of them, if you please."

"Very willingly, boys. Some build of shells: here are pictures of their nests.

Some build of leaves, and others of pieces of reed or light bark.

And a curious thing about those which build of light pieces of bark or reed is this, that they will make the top-piece come over so as to hide their heads, and prevent you from seeing them. Some build of sand; and then as the house would be so light that the water running from the spring might wash it down and carry it away, the wonderful little creature takes care to anchor it by fastening a pretty large stone to it when it has nearly finished it. And as the worm anchors it when it is too light, so it lightens it when it is too heavy, by fixing a bit of light wood or hollow straw to it to buoy it up."

"Well, this is truly a wonderful insect. Uncle Philip."

"Truly so indeed, boys. In all these cases it uses its water-proof cement, and if you break its house to pieces, and will patiently watch, you may see it build another. The insect always lives with its head out of doors, and its body inside; so that its head is firm and hard, while its body is soft."

"Uncle Philip," said one of the larger boys, "there is one thing I have been thinking about, as you have been talking: these little masons have no trowel, but I believe I know of one animal that uses something like that tool."

"Ah! What animal is it?"

"Why, I was reading the other day something about the beavers building their dams and their houses, and the book said that they built their houses of logs first, and then plastered them with mud, and that they used their tails for trowels."

"I am very glad to find that you remember what you read; but I am sorry that your book did not tell you the truth. There have been very strange stories told about the beaver; and these stories have been taken from one book and printed in another, so that an untrue account has gone down for a great many years. The beaver is very ingenious, but is not quite so much of a mason as you suppose."

"Well, Uncle Philip, will you tell us the truth about it?"

"Yes, boys, I will, so far as I know it myself. I have seen these animals, for they were once a great deal more common in our country than they are now; and many of the stories told of them are not true. But before I begin, let me tell you of one book which I think does tell the plain truth about them; and the truth is curious enough."

"What book is it, Uncle Philip?"

"It is a book written on American Natural History, by Doctor John Godman. I knew him, boys, and a most excellent man he was. He is now dead—and he died a Christian. The book he wrote you will find worth reading, when you get old enough to understand it. But now for the beaver.

"His tail is very broad and flat at the end, and might be used very well for a trowel; but when he builds his house he does not cut down trees, and place them first, and then fill up the cracks with mud-mortar; but all the sticks and mud (and stones too when the beaver can get them), are first mixed up together, and the beaver builds his house with this from the very foundation. As soon as he has placed a lump of this stuff upon the wall, he turns round and gives it a blow with his flat tail; and that, boys, is all he does with his tail for a trowel. Sometimes he slaps his tail upon the water when he is swimming; and some persons have supposed that this was done by the king, or ruler, to call his workmen. It may be so, but I do not believe it, because they almost always dive as soon as they have slapped the water; and I think it is probably a part of their motion in diving. In the autumn they cover the outside of their houses with mud, and they walk over it as they are at work, and their tails drag along upon it; and this I expect made persons first suppose that they were plastering it, with the tail for a trowel. When they are caught and kept, boys, they still keep up this fashion of slapping with the tail; so that I rather think it is part of the nature of the animal.

"At another time, perhaps, I will tell you more about the beaver; but it is now late, and I must bid you good morning."

"Good day, Uncle Philip."