Danny Dunn and the Weather Machine Read Online Free

them when I was a boy by taking some thin rubber from a balloon and stretching it over the top of a tin can. Stretch it very tight, and tape it down securely. In the center of it, glue a broom straw so that the end of the straw sticks out over the edge of the can. That’s your pointer. Glue a piece of cardboard, marked off with lines close together, to one side of the can, so that the straw can move up and down the edge of it. That will be your scale.
    â€œNow, when the air pressure increases, it will push down the rubber sheet, and the end of the straw will be pushed up on the scale. By checking the scale every day, you can tell whether the air pressure is high or low. Low pressure is, of course, associated with stormy weather, and high with fair weather.”
    â€œLet’s make one now, Professor,” Danny said enthusiastically. “Will you help us?”
    Professor Bullfinch took out his watch. “I can help you for a little while,” he said, “but I’ve got to keep an eye on the time. I must catch the one-thirty plane.”
    He shut his watchcase with a click and stood for a moment rubbing his chin thoughtfully. Then he said, “You can set up your weather station in this alcove. But while I’m away, please be careful of the things in my laboratory.”
    â€œWhere are you going, Professor?” Danny asked.
    â€œTo Washington. My friend, Dr. A. J. Grimes, has invited me to discuss my new engine with the chairman of the Academy of Scientific Research.”
    â€œYour new engine?” Danny’s eyes opened wide. “Is that the model you’ve been working on? Can we look at it?”
    â€œCertainly.” Professor Bullfinch led the way into the laboratory. On a long, stone-topped bench stood a gray metal cube, about two feet square. On each side were handles, on the back a knife switch, and on the front two long tubes, each shaped something like the nozzle of a garden hose. The Professor patted the top of this device.
    â€œThis is my ionic transmitter,” he said proudly. “It provides a way of sending electrical energy without wires, by means of two beams of charged particles. Inside this case is a wet cell battery. When I start the machine, the electrical energy of these batteries can be transmitted to the proper receiver and turned into light and heat—it can be made to light an electric bulb, for instance.”
    â€œThat’s keen!” Danny exclaimed. “Will you show us?”
    â€œNot if you want me to help you with the weather station,” the Professor replied. “I haven’t time for both. The engine can wait until I get back from Washington, my boy.”
    He turned toward the alcove. Then, suddenly, he stopped and swung round. “Danny,” he said.
    â€œYes, Professor?”
    â€œI know how curious you are, and how often you jump into things without thinking carefully of all the consequences.”
    â€œMe?” Danny said innocently. Then he blushed. “I guess you’re right,” he said humbly.
    â€œI want you to do something,” said the Professor.
    â€œYes, sir?”
    â€œThis time, I want you to exercise good judgment and discipline while I’m away. Think twice before you plunge into any—well—any rash ideas.”
    Danny sighed. “All right, Professor Bullfinch,” he said. “I promise.”
    â€œVery well.” The Professor, with a cheery smile, rubbed his hands together. “Now, let’s get to work. We just have time to make the barometer.”

CHAPTER FIVE
    â€œSomebody’s Crazy!”
    All that afternoon, after the Professor left for Washington, the three friends worked on the instruments for their weather station. Irene and Joe went home limp and exhausted, but eager for the morning, when they would begin forecasting.
    Danny stayed up late that night, reading all the books he could find, in his own and the Professor’s library, on