“Well in very dry countries, such as some parts of ours near the places called deserts,” said Mr. Blake, “men build large dams, and hold the water back in big ponds or lakes so it will last from one rainy season to another.  The water is let run from the lake through little ditches, or pipes, so that the thirsty plants may drink.  This is called the irrigation method, for to irrigate means to wet, soak or moisten with water.  Each farmer or gardener is allowed to buy as much water as he needs, opening little gates at the ends of the main ditches or sluices, and letting the water run over his dry ground, in which he has dug furrows to lead the water where he most needs it.

“And sometimes, when there is too little water to use much of it this way, the gardeners do what they call intensive cultivation.  Those are big words, but they mean that the man just hoes his ground every day around his plants, instead of perhaps once a week.

“You know there is moisture in the air, and at night dew falls.  This wets the ground a little, and by digging and turning over the earth around the roots of his plants, the gardener makes it very fine so it holds the moisture longer.  In this way a little bit of rain, or dew, lasts a long time.  Come out now, and I’ll show you something you perhaps have not noticed.”

Daddy took Hal and Mab to the garden, and with a hoe he pointed to a place around Hal’s corn stalks where the dry ground was hard, and baked by the sun.

A few strokes of the hoe and Daddy Blake had turned up some of the underlying earth.  Hal and Mab saw that it was darker in color than that on top, and when they put their hands down in it the earth felt moist.

“What makes it?” asked Mab.

“Because the underneath part of the ground held the moisture in it.  The top part was baked dry and the moisture had all gone away—­evaporated in the sun, if you want to use big words, just as water dries in your hands after you wash them, even if you do not soak it up with a towel.”

“Does a towel soak up water?” asked Mab.  “I thought it just wiped it off our hands.”

“No, the towel is like a sponge,” said Daddy Blake.  “The fuzzier the towel the more like a sponge it is.  Each little bit of linen or cotton, is really a tiny hollow tube—­a capillary tube it is called—­and these tubes suck up the water on your hands as the same fuzzy capillary tubes in a piece of blotting paper suck up the ink.  A towel is a sponge or a blotter.  And the earth is a sort of sponge when it comes to sucking up the rain and dew.  It also holds the water near the plant, when the ground is finely pulverized, so the tomato vine, the corn stalk or the bean bush can drink when it gets thirsty.”

“My!  There’s a lot to know about a garden; isn’t there?” said Mab with a sigh.

“Yes, there is,” agreed Hal.  “I don’t s’pose we’ll ever know it all.”

“No,” said his father, “you will not.  There will always be something better to learn, not only for you but for everyone.  But learn all you can, and learn, first of all, that plants must have sunshine, air and water to make them grow.  Now we’ll water the garden.”