"Oh, I see! This is where she would be;" and Gerda made two dots on the
orbit, each half-way between the two grandmothers.

"Good," said her father. "Now when she is in that position, day and
night, all over the earth, are each twelve hours long. We call them the
'Equinoxes.' It is a Latin word which means 'equal nights.'"

"In March and September do we have a day when it is twelve hours from
sunrise to sunset, and twelve hours from sunset to sunrise?" questioned
Gerda.

"Yes, and it is the same all over the earth the very same day," repeated
Lieutenant Ekman. "If you will look in the almanac when you go home, you
will see just which day it is."

Gerda studied her drawing for a few minutes in silence. "I think I
understand it now," she said at last.

"It is easy to understand after a little study," her father told her;
"but everyone has to see it for himself, just like the midnight sun.

"When the North Pole, or Fru Earth's head, is turned toward the sun we
have the long summer days in Sweden. When it is turned away from the sun
we have the long winter nights. The nearer we go to the pole, the longer
days and nights we have. If we could be directly at the pole, we should
have six months of daylight and six months of darkness every year."

"What did you say?" asked Birger, who came around the corner of the hut
just in time to hear his father's last words.