"It isn't like mine either," said Donald.

"We may have one some time that will be more like yours," said Uncle
Robert, "for these records are made at eight in the evening as well as
in the morning."

"Uncle," said Frank, looking closely at the map, "here it says 'High,'
and there it says 'Low.' What does that mean?"

"It means," said Uncle Robert, "that here there is a low barometer, and
there the barometer is high."

"Barometer," said Donald. "What is a barometer, uncle? Is it like a
thermometer?"

"Well, not exactly," was the reply. "With the thermometer, you know, we
tell the temperature of the air, and with the barometer we tell how
heavy it is."

"How heavy the air is!" exclaimed Susie. "How funny! Why, uncle, air
doesn't weigh anything, does it?"

"More than you think, little girl," said Uncle Robert, smiling. "But
perhaps we can prove whether it does or not. Frank, will you get a pail
of water? Donald, see if you can find a cork some place; and Susie, run
in and get a tumbler."

When all was ready Uncle Robert asked Frank to fill the pan with water,
and Donald to put the cork into it.