“It is a mark to show when it is exactly twelve o’clock.”
“Let me go and see it,” said Rollo, “while my sand is drying.”
Rollo followed Jonas off into the barn, and when there, Jonas pointed to a small line which he had cut with his penknife upon the barn floor. It began at the foot of one of the posts, by the side of the door, and extended back into the barn exactly straight.
“Is that the noon mark?” said Rollo. He was surprised to see that a noon mark was nothing but a cut with a penknife upon a barn floor.
“Yes,” said Jonas; “that is a meridian.”
“A meridian!” said Rollo, looking upon it with an air of great curiosity and respect.
“Yes,” said Jonas; “a line drawn exactly north and south, is called a meridian line; and that is exactly north and south.”
“What do you call it a noon mark for?” said Rollo.
“Because,” said Jonas, “the shadow of the edge of the door post will always be exactly upon it at noon. So that I can always tell now when it is noon, by the shadow of the post upon my noon mark, if the sun shines.”
All this was very new and very curious to Rollo. He had never seen or heard of a noon mark before; and it seemed to him a very simple and beautiful way of knowing when it was noon. He asked Jonas how he found out about it, and Jonas told him that he had been reading about it in a book on astronomy.