"Of course," the Forecaster continued, "a really progressive fruit-grower ought to make himself partly independent of the Weather Bureau. He can put up frost-alarm thermometers."
"What are they, sir?" asked Anton.
"They're thermometers with an electrical attachment, something on the principle of the thermostat, which you see nowadays in big buildings. A thermostat is electrically connected with a tiny lever, and when the air of a room gets to a certain heat, the increasing temperature operates a lever and closes the steam pipe which brings the heat. When the temperature falls below a certain point, the lever is released and the steam rises again. The same principle is used as a fire alarm. When the air inside a building rises to a point hotter than it could naturally do, it operates a lever which rings an alarm bell. The frost thermometer acts exactly on the same principle. When the temperature of the air, near a fruit orchard, falls to within three or four degrees of the point at which the fruit will be harmed, the fall of the mercury breaks an electric circuit which starts an alarm bell ringing in the owner's house, perhaps a half mile away."
Ringing the Frost Alarm.
Thermometer with electric attachment which wakes the neighborhood when the grip of a cold wave menaces ruin to a fruit crop.
Courtesy of U.S. Weather Bureau.
"I've been wondering," began Anton in his meditative way, "whether it wouldn't cost more to heat all the out-of-doors than it would be to lose some of the fruit."
"You haven't got the idea of it at all," the weather expert said briskly. "It's got nothing to do with heating the whole of out-of-doors."