That soil is the best where all three are found mixed together. Thus-where there is heavy clayey soil, it retains too much water, and is very cold. If you mix lime with it, the heat of the lime will correct the coldness. At the same time (for you remember that lime is very absorbent), it causes the water to pass through more easily.

Ör, again, this clayey soil may be too hard, and too heavy for the roots of the flowers to work their way through it; then the sand and stones of the silica, if mixed with it, will loosen it even more than the lime.

contains decayed animal and vegetable substances. So, we find that every year thousands of leaves fall off from the forest trees. The leaves also, and flowers of dead plants, dead weeds, old pea-shells, and other husks, the old roots of the grass, all serve to make rich mould; even the little smooth green mosses, when they die, serve to make the ground richer.

Sea-weed, too, is used as a manure; and these sea-weeds are burned to make a substance called potash. Even the smoke which goes up the chimney forms soot, full of fine carbon.

W. Yes; I have noticed how careful the chimney-sweeps are of their bag of soot. So they take it home to feed their plants, do they? What is "carbon," papa?

Listen!

P. Never mind now. Not only do the vegetables die every year, but innumerable quantities of small animals, insects, flies, grubs, &c., and they all serve to make earth. They supply carbon and ammonia, another gas which vegetables feed upon.

The bones of animals, too—

W. Ah! to be sure, the phosphate of lime, and the carbonate of lime in them are earths.

P. Now, in order that vegetables may grow well, every particle of the soil ought to be surrounded with air. This air in the earth will then unite with the carbon of the decayed animals and vegetables and form cabonic acid.

Ion. Ah! Just as the air which flows down my throat unites with the carbon in my blood, and makes breath.

L. The mould in my garden, papa, is very porous. There are little spaces between its particles, so that the air may get in-and now

I see one reason why the gardener digs up the mould and turns it over. It is that the air may get at it, and that it may not be too hard. Then, clayey soil alone cannot be very good soil for vegetables.

P. No, it is not. You may now learn, that this soil on the surface of the earth is called vegetable soil.

W. And what is underneath the vegetable soil, papa?

P. If you dig down a little depth, you will reach an earth which is formed of sand and gravel.

Ion. And what is below that? P. Beneath that you would find some hard blue clay, mixed with great numbers of large rounded stones. These stones have been Worn to a round shape, by the washing of water; and are called boulders.

L. But how could the water wash them, papa, if they are underneath the ground?

P. Why, they were not always covered over so. That blue clay, at one time, was on the surface of the earth. This is the way it happened. A long, long time ago, before man was made, and before GOD said, "Let the dry land appear," the waters were not "gathered together in one place," but made great deluges, which washed all over the earth's crust. Then, when they went back again, they left behind them this clay, and the round stones or boulders.

L. Then, I suppose that the sand and gravel on top of the clay was also brought there by the water.

P. Yes. And if you could cut through the middle of this globe just as you would take a knife and cut an apple in half-you would see that the crust of this earth consists of several layers, or slices, of earths, placed on top of each other.

You would see the thin slice, or "stratum," of clay and boulders, and above that, a thin layer, or stratum, of sand and gravel, which the water had laid over it.

W. I suppose, papa, that the sand and gravel formed a sediment at the bottom of the water, just as the coffee-grounds do sometimes at the bottom of your cup.

Above the

P. That is right; and thus a slice of earth, or "stratum," as we call it, was formed. sand and gravel is the very thin layer of vegetable soil.

L. But, papa, what is there under the clay and boulders?

P. Åh, I cannot stop to tell you now; but perhaps we will go down a little deeper in the next lesson.

L. Oh, papa! stop one minute, please. Will you tell us where did those great boulders come from?

P. I cannot tell exactly -I was not here when the sea deposited them. It is believed that these boulders are great pieces of rock, which have been washed down from the mountains, especially from the mountains in the Northern regions. The snow on these mountains melted perhaps; or, coming down in immense masses, it formed great torrents and waterfalls. These torrents rushed on, and as they came down with a wonderful force, they broke off large pieces of rock. Then, as these masses of rock came tumbling down with the torrents, they dashed one against another, and broke into smaller pieces.

When they were thus borne into the sea, they were continually washed backward and forward; and thus, by continually grinding together, they broke off each other's sharp edges, which were worn more and more until they became rounded, and were called BOUL

DERS.

P. We will not learn the names of any new figures for the present -but, to-day and next Saturday,

I will supply you with a series of drawings for practice. Some will be easy, and some difficult.

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