Bells Ringing
“One Sunday before church,” interposed Jules, “I was watching from a distance the ringing of the bell. I saw the tongue strike and the sound did not come until later. Now I see the reason.”
“If you count the number of seconds between the appearance of the flash and the instant the thunder begins to be heard, you can tell what distance you are from the storm-cloud.”
“Is a second very long!” Emile asked.
“It is about the length of one beat of the pulse. All we have to do, then, is to count, one, two, three, four, etc., without haste, but not too slowly, to have about the number of seconds. Note the instant the flash lights up the stormy cumulus, and count slowly until you hear the thunder.”
With watchful eye and attentive ear all began the observation. Finally a flash was seen. They counted, the uncle beating time. One—two—three—four—five—At twelve came the thunder, but so faint that they could only just hear it.
“It took twelve seconds for the sound of the thunder to reach us,” said Uncle Paul. “From what distance does it come, if sound travels 340 meters a second?”
“You must multiply 340 by twelve,” replied Claire.
“Well, Miss, do it.”