the boy replied. "I tried to explain it the other day
and I found I hadn't the least idea why, myself. I asked Father, but he
didn't know either."

"Yet it's quite simple," the Weather Man answered, "and if you boys are
going to be real meteorologists, you ought to know the reasons for
things. First of all, why is the sky blue?"

There was a gasp of astonishment, followed by silence.

"Sure, 'tis the air that's blue," hazarded the printer.

"That doesn't help much," the Forecaster said, "though perhaps it does,
a little. Why is the air blue?"

The Irishman shook his head.

"Why is annything blue?" he asked.

"That's just what I'm going to tell you," the Weather Man answered, "and
you want to listen carefully, boys, because the colors of the sunset
depend a great deal on the weather. You can foretell weather from the
sunset."

"Yo' sho' can," interrupted Dan'l. "Don't yo' remember Mammy's old
rhyme:

"Evenin' red an' mornin' gray
Certain signs of a beautiful day;
Evenin' gray an' mornin' red,
Sends a nigger wet to bed."

"All those old rhymes are fakes, though, Dan'l," declared Anton, with
the importance of his newly acquired weather knowledge.

"Easy there, easy there!" warned the Forecaster. "Not so fast. A good
many of those old rhymes are mighty good weather forecasts. That one is,
for example."

"You mean, sir, that a red sunset and a gray sunrise really tell that
the weather is going to be fine?"

"Yes, to a great extent, they do."

"Why, Mr. Levin?"

"Because they show the state of the atmosphere, boys. Rain can't fall
unless there is dust. Every little drop of rain has a grain of dust in
the middle. The colors of the sunset, too, are due partly to dust. Not
only that, but colors of the sunset vary as the particles of dust which
reflect the rays of light, are enveloped by water vapor.

"A piece of dust, without an envelope of water, is smaller than one with
a little wetness around it. When more water vapor gathers around the
piece of dust, the drop becomes bigger. When the sunset is red, it is a
sign that it is shining on very small bits of dust, or that the
condensation of water vapor into rain has not advanced very far. If,
however, the sunset sky is gray, that means that the upper air is
saturated, that it has all the water it can hold, and, of course, rain
is likely to come soon."

"I should think, then," said Anton, "that gray in the morning would be a
bad sign, too."