Then Glinda made a little island, covered by a glass dome, and sunk it in a pond near her castle, and experimented in magical ways to bring it to the surface.

She made several such experiments, but all were failures.

It seemed a simple thing to do, yet she could not do it.
Nevertheless, the wise Sorceress did not despair of finding a way to liberate her friends.

Finally she concluded that the best thing to do was to go to the Skeezer country and examine the lake.

While there she was more likely to discover a solution to the problem that bothered her, and to work out a plan for the rescue of Ozma and Dorothy.
So Glinda summoned her storks and her aerial chariot, and telling her maids she was going on a journey and might not soon return, she entered the chariot and was carried swiftly to the Emerald City.
In Princess Ozma's palace the Scarecrow was now acting as Ruler of the Land of Oz.