rth they are northeasterly, to the west, or
behind it, they are northwesterly, and to the south, they are
southeasterly, all curving into the centre and shifting as the 'low'
advances. As these 'lows' travel along the storm track at an average
rate of four hundred miles a day, as mountains interfere, and as the
shape of a 'low' in America isn't quite round, but looks like a sort of
crooked oval, it takes close figuring to find out what the wind is going
to do."

"And where does the cold wave come in?" persisted the farmer.

"That comes after the cyclone," explained Anton. "A 'low' means that the
pressure of the atmosphere is less than usual, and, consequently,
doesn't press the mercury up so far in the barometer. The air weighs
less, that shows that it must be expanding. The winds in front blowing
into a 'low' are generally warm winds. When a 'low' is traveling fast,
with a 'high' or 'anti-cyclone' behind, the colder winds come rushing
forward to take the place of the rising warm air and they bring colder
weather with them. The freeze comes during the early clearing weather of
a 'high,' before the anti-cyclonic winds--which blow in the opposite
direction, the way of the hands of a clock--have had a chance to steady
down."

"Then," said the farmer shrewdly, "if you get reports of wind and of
barometer from points to the west and northwest, you can tell when a
cold wave in on the way. Is that it?"

"Exactly," the Forecaster replied. "We cannot always tell, of course,
when the weather is going to be a little colder or a little warmer, but
a cold wave, serious enough to damage crops and property, can always be
foretold. Remember your storm tracks again. In this county, in the State
of Mississippi, we are very unlikely to get a freeze, unless there is a
rapidly moving 'low' passing up towards the Ohio and St. Lawrence
Valleys followed by an equally energetic 'high' plunging down from the
Canadian Northwest."

"And can you always tell what the weather is like, all over the
country?"

"Yes, indeed," the Forecaster answered. "There are two hundred official
stations scattered all over the United States and the West Indies, each
one carefully selected because its site is a key station to weather
changes. Twice a day, exactly at eight o'clock in the morning and eight
o'clock in the evening, the observations are taken at each station."

"And have they all got rain gauges like mine?" asked Anton.

"Yes, all of them."

"A