Now, Ross," said Anton, "pour in the ice-water slowly."

Ross picked up the pitcher and began to let the water trickle in a tiny
stream into the bright tin cup. Anton went on stirring.

Steadily the mercury descended in the tube as the water in the cup grew
colder and colder. Ross poured in more and more slowly. Then suddenly,
quite suddenly, while both boys were watching, the brightness of the tin
cup clouded over, as though with a sudden fog. Anton drew out the
thermometer and looked at it.

"The dew-point's only thirty-four," he cried, "and as we've got to
figure frost at three or four degrees lower, it'll be so cold that there
won't be any fog to stop a freeze. Ross, it's just the night for a
killing frost. What do you think we'd better do?"

The older lad hesitated.

"If you don't mind, Anton," he said, "I'll stay to supper, and we'll see
what your night observations say."

By evening the threats of a frost were even more definite and the two
boys consulted what had best be done.

"I can easily get Father to start his fire-pots," said Ross, "we got
them all fixed up this winter. Bob's dad has got some fruit, and we can
warn him by wireless, and we could get a lot of the fellows together. I
don't want to make a mistake, though. If we suggest that the fire-pots
ought to be started and then it doesn't freeze, we'll hurt the League a
lot more than we'll help it."

"I wish we could talk it over with Mr. Levin," said Anton, "but he's
down with one of his sick spells and we oughtn't to disturb him.
Whatever we do, we've got to do it on our own."

"Let's get Bob here," suggested Ross, "he's got a steady head."

"And Fred," Anton added, "he's read all the Weather Bureau stuff on
Frosts, I know. He's been writing his articles for the _Review_ from
them."

"All right," said Ross, "I'll slip over and call for Fred and you get
Bob on the wireless and ask him to come over here."

An hour later, the four boys were poring over the weather maps,
comparing notes and observations and trying to decide whether they ought
to do anything. Fred, always ready to take up something new, was for
plunging ahead, on the chance that there might be frost, but doubted
whether a frost was likely. Ross, as head of the League, was a little
timid and afraid to make a serious mistake. Anton was firmly convinced
that a killing frost would come before morning. Bob settled it.

"Better for the League to be laughed at than chance having the