rivers; then turned her eyes toward the sun, which was
becoming paler and paler, its golden glow shedding a drowsy light over
the hills.

"How still it is!" she said softly. "All the world seems to have gone to
sleep in the midst of sunshine."

"It is exactly midnight," said her father, looking at the watch which he
had been holding in his hand.

Birger closed his camera and slipped it into his pocket. "There," he
said, "I have a picture of the sun shining at midnight, to prove to Oscar
that it really does shine. Now I am going to gather some flowers to press
for Mother;" and he ran off down the side of the hill.

Gerda found a seat on a rock beside the hut, and sat down to watch the
beginning of the new day. The sun gradually brightened and became a
magnificent red, tinging the clouds with gold and crimson, and gilding
the distant hills. A fresh breeze sprang up, the swallows in their nests
under the eaves of the hut twittered softly,--all nature seemed to be
awake again.

"I've been thinking," said Gerda, after a long silence, "that I told
Hilma I should understand about the midnight sun if I should see it; but
I'm afraid I don't understand it, after all."

"It is this way," Lieutenant Ekman began. "The earth moves around the sun
once every year, and turns on its own axis once every twenty-four hours."

"That is in our geography," Gerda interrupted. "The path which the earth
takes in its trip around the sun is called its orbit. The axis is a
straight line that passes through the center of the earth, from the North
Pole to the South Pole."

"That is right," said her father; "and if old Mother Earth went whirling
round and round with her axis perpendicular to her orbit, we should have
twelve hours of daylight and twelve hours of darkness all over the earth
every day in the year."

"I suppose she gets dizzy, spinning around so fast, and finds it hard to
stand straight up and down," suggested Gerda.

"No doubt of it," answered her father gravely. "At least she has tipped
over, so that in summer the North Pole is turned toward the sun, but in
winter it is turned away from the sun."

"Let me show you how I think it is," said Gerda eagerly. She was always
skillful at drawing pictures, and now she took the paper and pencil
which her father gave her, and talked as she worked. "This is the sun and
this is the earth's orbit," and she drew a circle in the center with a
great path around it.

"This is Mother Earth i