"The captain says that the frost giants threw all these rocks out
here when they were having a battle with old Njord, the god of the sea,"
she said. Then, as she caught sight of a lighthouse on a low outer
ledge,--"Why, Father!" she cried, "I thought we were going to stop at
every lighthouse on the coast."

"So we are, after we leave the Skärgård," replied Lieutenant Ekman. "I
came down as far as this several weeks ago when the ice went out of the
fjord. There are two or three months when all this water is frozen over
and there can be no shipping; but as soon as the ice breaks up, the lamps
are lighted in the lighthouses and I come down to see them. Now it is so
light all night that for two months the lamps are not lighted at all
unless there is a storm."

Gerda ran to the rail to wave her handkerchief to a little girl on the
deck of a lumber vessel which they were passing.

"The lighthouse keepers have a good many vacations, don't they?" she said
when she came back.

"Yes," replied her father; "those on the east coast of Sweden have
several months in the winter when the Baltic Sea and the Gulf of Bothnia
are covered with solid ice; but on the south and west coasts the
lighthouses and even the lightships are lighted all winter."

"Why is that?" questioned Birger, coming to join them.

"There is a warm current which crosses the Atlantic Ocean from the Gulf
of Mexico and washes our western coast. It is called the Gulf Stream.