“What do you mean by that, father?” asked Rollo.
“Why, if the attractive powers at the two ends were both alike in their nature, only one was stronger than the other, then the difference would be in degree; but there is a difference in the nature of the magnetism itself. In fact, the magnetisms of the two ends are of opposite natures in some respects.”
“Why, both ends attract the sand,” said Rollo, “just alike.”
“True,” said his father; “they seem to attract the sand in precisely the same way; and, looking at the bar, as I now hold it up,” he added, “with the sand adhering in the same way at the two ends, one would suppose that they were both magnetic alike. But, in fact, there is a great difference between them.”
All the company looked upon the two ends of the bar, as Rollo’s father held it up, wondering how he would show that there was any difference between them.
“Now, in the first place,” he continued, “we must get the sand off of the ends. Do you think you can get it off for me, Rollo?” said he.
Rollo took the bar very eagerly, and attempted to brush the sand back upon the paper. He succeeded in brushing off a little of it; but the greater portion remained. When he rubbed upon one side, it moved round to the other; and he could not get it off.
“Hand it to me,” said his father, “and I will show you how it can be done.”
He also asked Jonas to hand him the tongs, which were standing by the side of the fire. He then held the tongs over the sheet of paper, in a horizontal position, and gently rapped the end of the magnet against them, letting the end project a little over the tongs. This knocked all the sand off, and left the bar clean as it was before.
“Now let me see,” said he, “what was it that I was going to tell you next?”