t is speeding up, you see, having traveled eight hundred miles
since yesterday. The cold wave 'high' from Medicine Hat has traveled
along its usual track and is now central over Kansas, with clear skies
and a drop of thirty degrees in temperature. There was a severe freeze
in Kansas last night, with zero temperatures, and freezing point was
touched on the Mexican border."

"Whew," whistled the farmer, "and is that on its way here?"

"It is," the Forecaster answered. "Your temperature?" he continued,
turning to the boy.

"Thirty-seven," Anton answered.

"Going down rapidly, you see. The wind, Tom?"

"Northwest."

"Blowing outwards from the rapidly approaching 'high.'"

"What's the barometer?" asked the farmer, who was quickly grasping the
manner of reading a weather map.

"It has gone up again to 30.02. The cold wave is coming fast. Since
Dodge City, Kansas, is about five hundred miles from here, and since the
'high' is traveling at about seven hundred miles a day, and as,
moreover, there is generally a slight slowing up as it makes the turn,
the centre of the 'high' ought to strike us here about six o'clock
tomorrow morning. The cold wave, however, is in advance of the centre,
so Mr. Tighe, you need to be prepared for a cold wave tonight.

"If you ship your potatoes this afternoon, as you planned to do, they
would meet severe weather and might get frozen. If you ship them
tomorrow, you might be safe, but you couldn't be sure, because the
'high' is turning northwards and therefore its eastward distance is not
so great. If you ship them on Monday you would be safe, but even then
you could not ship them to New York, for a fast train might overtake the
tail of the cold wave. On Tuesday you can safely ship them to any part
of the United States."

The farmer stepped back from the table and his eye roved over the boys.

"And was that the way that you lads figured out that my fruit was likely
to be frozen?" he asked.

"Yes, sir," said Anton, "that was how."

"It's a marvel," the farmer declared. "I don't see why more people don't
use these Weather Maps."

"Hundreds of thousands of people do," the Forecaster replied. "You'd be
surprised, Mr. Tighe, if you knew how big business firms all over the
country study these changes of weather. Heating and lighting plants of
great cities study conditions of cold and of darkness. Municipal
systems, with exposed water mains, take precautions against frost.
Large stockyards