“Now, Jonas,” said he, “sprinkle some sand upon it from my sand-box, carefully, and see where the sand will adhere.”
So Jonas took the sand-box, and held it over the bar, not very high, and moved it slowly along, from one end to the other, and thus sanded the magnet all over. The sand fell off of it, however, freely, at every part except the ends; and Jonas, observing that it seemed to adhere there, held the sand-box a little longer over those places; and thus there was formed a sort of a black bur at the extremities, consisting of an accumulation of the black particles of sand. Rollo’s father then took up the bar carefully, and passed it around, so that all who were seated at the table could examine it closely.
“It is thickest on all the edges and corners,” said Rollo.
“Yes,” said his mother; “and the sand forms little black bristles, pointing off in every direction.”
They all examined it attentively, and observed the little black bristles pointing out every way from the edges and corners at the ends.
“This shows you,” said Rollo’s father, “exactly how the magnetic power, so far as its attractive force on other bodies is concerned, is distributed. You see it resides in the two ends, and the two ends seem to be exactly alike.”
“Yes, sir,” said Rollo, “exactly.”
“They seem to be so,” continued his father; “but the fact is, the magnetism of one end is very different from that of the other.”
“I see that the cluster of sand is a little bigger at one end, than it is at the other,” said Rollo’s mother. She was more observing than the others, and had noticed a little difference, which had escaped the rest.
“That indicates only a difference in degree,” said Rollo’s father; “but there is a difference in kind.”