ed to find how
rapidly the water separated the light things which would float upon the
top, from the heavy sand which would sink to the bottom. He kept pouring
off the water, and pumping in more, until at length no more sticks and
leaves came off, and the water appeared pretty clear. Then he carried
the sand away, and spread it out upon a clean board in the sun to dry.

While he was thus at work preparing the sand for his hour-glass, Jonas
happened to come by, and asked Rollo what he was doing. Rollo told him
that he was making an hour-glass. Jonas looked on for a few minutes, and
then he told Rollo that he thought that was a pretty good plan. "And
_I_ am going to have a time-keeper, too," said he.

"Are you?" said Rollo. "What?"

"I am going to make a dial," said he.

"A dial!" said Rollo; "what, a real dial?"

Rollo had an idea that a dial was exceedingly complicated and difficult
to make, or to understand; and, in fact, it is difficult to make one
that shall be exact in its indications. He did not think it possible
that Jonas could make one.

"Yes," said Jonas, "a real dial; and I have got a noon mark already."

"A noon mark!" said Rollo; "what is a noon mark?"

"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 abou