ot say that when the sun came out
bright and hot, it dried up the fog? and is not the fog the very thing
that keeps the sun from coming out?"

"Yes, my dear; but fogs usually gather at night, and when the sun rises
in the morning, he goes to work at once to heat them up and make them
disappear. But when he finds them very thick, and is hindered by cold
air, he may be a good part of the day in working his way through, or he
may even have to go down before he is able to show himself. Generally,
however, he gets help from the wind, and then the fog goes off in a
hurry."

"Is there no way," asked Gus, "of knowing when the wind will spring up,
and give us some clear cold weather? Ted Wynant's cousin has an
ice-boat, and we are all waiting for a ride on the river."

"There is Old Probabilities," said Jack; "but he can only tell a day or
two ahead, and seems rather uncertain at that, and afraid to express a
decided opinion. It is a little this or a little that, a little cloudy
or a little cooler, and the wind is to blow a little in nearly every
direction. Most people laugh when they talk about him, as if he was not
of much account, or had grown stupid in his old age. If he would only
foretell a hurricane or a deluge, and bring it around, why, then we
would know what he is good for."

"Such a test would be rather costly," said the Professor, smiling. "It
is better to give the old gentleman a little time to establish his
reliableness; for in truth he is yet very young--a mere child of eight
or ten years. And considering that he undertakes to forewarn our whole
country as to the coming weather, so that everybody will have time to
get ready for it, we must admit that he is doing all that his age
warrants."

"Where does he live?" asked Gus.

"We have been talking somewhat absurdly," replied the Professor.
"Instead of a single person, there is what is called the United States
Signal Service, which has been in operation eight or ten years, and
comprises some two hundred or more men, scattered all over the country,
from Maine to California, and from the Gulf of Mexico away out to the
Northwestern lakes. The men at these various stations watch the weather
very closely, and at a particular time every day send word regarding it
by telegraph to the main office at Washington, where the different
reports are carefully studied, and an opinion formed as to what the
weather is likely to be in different sections of the country during the