"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...o...b..t," and she drew a circle in the center with a great path around it.

"This is Mother Earth in the summer with the sun shining on her head at the North Pole," and a grandmotherly-looking figure in a Rattvik costume was quickly hung up on the line of the orbit, her head tipped toward the sun.

"Here she is again in winter, with the sun shining on her feet at the South Pole," and Gerda drew the figure on the opposite side of the orbit with her head tipped away from the sun.

"That is exactly how it is," said her father. "But do you understand that, when she is slowly moving round the sun, she is always tipped in the same direction, with the North Pole pointing toward the north star; so there comes a time, twice a year, when her head and her feet are both equally distant from the sun, which shines on both alike?"

"No," said Gerda. "When does that happen?"

"It happens in March and September, when Mother Earth has travelled just half the distance between summer and winter."

"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.

"We were explaining how it is that the farther north we go in summer, the longer we can see the sun each day," said Gerda.

"Let me hear you explain it," suggested Birger, trying to find a comfortable seat on the rocky ground.

But Gerda drew a long breath of dismay. "Oh, Birger, you should have come sooner!" she exclaimed. "I understand it perfectly now; but if we go through it again I shall get all mixed up in my mind."

Lieutenant Ekman laughed. "I move that we stay up here and watch the midnight sun until we understand the whole matter and can stand on our heads and say it backwards," he suggested.

"I'm willing to stay all summer, if we can drive off in the daytime and see some Lapp settlements," said Birger, who had made friends with a young Laplander that morning at the Gellivare station.

"But it is daytime all the time!" cried Gerda. "When should we get any sleep?"

"I must be back in Stockholm by the middle of July," said Lieutenant Ekman; "but if your friend knows where there are some Laplanders not too far away, perhaps we can spare time to go and see them."

"Yes, he does," said Birger eagerly. "The mosquitoes have driven most of the herds of reindeer up into the mountains, but Erik's family are still living only a few miles north of Gellivare."

"What is Erik doing in Gellivare?" questioned Herr Ekman.

"He is working in the iron mines," Birger explained. "He wants to save money so that he can go to Stockholm and learn a trade. He doesn't want to stay here in Lapland and wander about with the reindeer all his life."

"So?" said Lieutenant Ekman in surprise. "Your friend Erik seems to have ambitions of his own."

"Look at Gerda!" whispered Birger suddenly.

Gerda sat on the ground with her back against the hut, and she was fast asleep. "Poor child," said her father, as he carried her into the hut and put her on a cot, "she has been awake all night. When she has had a little rest we will go back to Gellivare and look up your friend Erik.

After we have all had a good night's sleep, we shall be ready to make a call on his family and their reindeer."

CHAPTER VII

ERIK'S HOME IN LAPLAND

"This is the best part of our trip," Gerda said, two days later, as she was standing in the shade of some fir trees at one of the posting-stations a few miles from Gellivare, waiting for fresh horses to be put into the carts. "I have been reading about Laplanders and their reindeer ever since I can remember, and now I am going to see them in their own home."

"Perhaps you will be disappointed," Birger told her. "Erik says that his father's reindeer may wander away any day to find a place where there is more moss, and if they do, the whole family will follow them."

"Where do they go?" asked Gerda.

"There is a treaty between Norway and Sweden, more than one hundred and fifty years old, which provides that Swedish Lapps can go to the coast of Norway in summer, and Norwegian Lapps can go inland to Sweden in winter,"

Lieutenant Ekman told the children.

"Yes," said Erik, "when the moss is scanty or the swarms of mosquitoes too thick, the reindeer hurry off to some pleasanter spot, without stopping to ask permission. Perhaps we have been in camp a week, perhaps a month, just as it happens; but when we hear their joints snapping and their hoofs tramping all together, we know it is time to take down the tent, pack up everything and follow the herd to a new pasture."

"I am glad we are out of sight of the photograph shops in Gellivare, anyway," Birger told Erik, when they were seated in the light carts and were once more on their journey. "If I could take such good pictures myself, I shouldn't care; but all my pictures of the midnight sun make it look like the moon in a snow-bank."

Just then Gerda, who was riding with her father, called to Birger, "Stop a moment and listen!" So the two posting-carts halted while the children listened to the music of a mountain stream not far away. Mingled with the sound of the rushing water was the whirr of a busy sawmill in the depths of the woods, while from the tree-tops could be heard the call of a cuckoo and the harsh cry of a woodp.e.c.k.e.r.

Soon they were on their way again, pushing deeper and deeper through the Lapland forest; their road bordered with green ferns and bright blossoming flowers, their path crossed now and again by fluttering b.u.t.terflies.

"This is just the right kind of a carriage for such a road, isn't it?"

said Gerda, as the track led through a shallow brooklet.

"Yes," answered her father; "a few of the roads in these northern forests are excellent; but many of them are only trails, and are rough and rocky.

If the cart were not so light, with only one seat and two wheels, we should often get a severe shaking-up."

"How does it happen that we can get such a good horse and cart up here among the forests?" asked Gerda.

"As there is no railroad in this part of Lapland, the Swedish government very thoughtfully arranges for the posting-stations, and guarantees the pay of the keepers for providing travellers with fresh horses," her father explained. "The stations are from one to two Swedish miles apart, and everyone who hires a horse is expected to take good care of him."

"I'm afraid we shall have to make this horse go faster, or we shall be caught in a thunder-storm," said Gerda, looking up through the trees at the sky, which was growing dark with clouds.

"You are right," answered her father; and at the same moment Erik looked back and shouted, "We must hurry. Perhaps we can reach my father's tent before the rain comes."

Then, glancing up again at the black clouds, he said to Birger, "We shall soon hear the pounding of Thor's hammer."

"How do you happen to know about the old Norse G.o.ds?" questioned Birger.