So she came out through the gate, and asked Mr. Holiday to wait a moment while she went to where Rollo was standing, and took hold of the string. But he said that it would not be necessary for her to go there, as she could take hold of his end of the line just as well, and let Rollo strike the other end.
They accordingly performed the experiment in that way, and Rollo's mother could feel the vibrations very distinctly.
"One thing you must observe," said Mr. Holiday; "and that is, that the vibrations pass along from one end of the line to the other very quick indeed. We feel them at one end almost at the same instant that the other end is struck."
"Exactly at the same instant, sir," said Rollo.
"No," replied his father, "not exactly at the same instant, though it is very nearly the same."
"I did not see any difference," said Rollo.
"No," replied his father, "you cannot perceive any difference in so short a string, but if we had a string, or a wire, a mile long, I presume that we should find that it would require a sensible period of time to transmit the vibrations from one end to the other."
"What do you mean by a sensible period of time, father?" asked Rollo.
"Why, a length of time that you could perceive," said his father; "just as it was with the man cutting wood. We could see that some time elapsed between the striking of the blow, and our hearing the sound."
"Yes," said Rollo, "just as long as it took him to lift up his axe."