The boat sails into a lock and great gates are closed behind it. Then
water pours in and lifts the boat slowly higher and higher until it is on
a level with the water in the lock above. The gates in front of the boat
are opened, it sails slowly into the next lock, the gates close behind
it; and that lock in turn is filled to the level of the one above.

The boat now wound along between the high green banks of the
Södertelje Canal until it entered the first of the locks. Birger and
Erik ran to the rail to watch the opening and closing of the gates, and
the lowering of the boat to the level of the Baltic Sea; but Gerda
preferred to talk with some old women who came on board with baskets full
of kringlor,--ring-twisted cakes.

The cakes looked so good, and everyone who bought them seemed to find
them so delicious, that at last she ran to ask her father for some money;
and when the boat had passed the lock and was once more on its way, she
presented a bagful of cakes to Birger and Erik.

"The Vikings had no such easy way as this of getting from Lake Mälar out
into the Baltic Sea," said Lieutenant Ekman, coming up to find the
children, and helping himself generously to the kringlor.

Gerda looked at the gnarled and sturdy oaks that lined the banks of the
canal like watchful sentinels. "The Vikings must have loved the lakes and
bays of the Northland," she said. "Perhaps they begged All-father Odin to
let their spirits come back and make their homes in these trees."

"No doubt they did," replied her father, gravely enough. "I suppose when
the trees wave their arms and shake themselves so violently they are