x up your costumes."

To save her life, Madge could not help looking curiously at David. It
was the usual hour in the afternoon when the young man disappeared.
When, late that afternoon, the lad came home he had lost his cheerful
mood of the morning. He was sullen and downcast. David had made up his
mind that his best chance to restore the stolen property to Miss Betsey
Taylor and Mrs. Preston was on the night of the fancy dress ball. The
upstairs part of the house would then probably be empty, and no one
would think of him or notice him. At any rate, he dared not wait longer.
As soon as Tom and the other boys returned, the houseboat party would
start off up the river again in tow of the "Sea Gull," and his
opportunity would be lost.

CHAPTER XXI

THE INTERRUPTION

All afternoon, just before the night of the fancy dress ball, the four
girls took turns watching at the front windows of the Preston house for
the belated boys. In spite of Tom's telegram, plainly stating the day of
their arrival, the motor launch boys had not put in an appearance. Soon
after luncheon David went down to the river bank to watch for them. At
six o'clock he came back to say that he had waited as long as possible
and had seen no sign of the "Sea Gull." It looked as though the boys had
been delayed.

The girls were in despair. Here they had planned a wonderful surprise
party for the boys, and their guests of honor were not going to be
present. The young people from the nearby country houses had been
invited to the dance, to begin at eight o'clock that evening, so it was
quite impossible to put it off.

At half-past eight the old Virginia homestead, where belles and beaux
had made merry many long years before, was gay with the voices of the
invited guests. But the dancing had not yet begun. Each time the old
door-bell rang the four girls hoped it meant the return of the four
boys.

Under the great curved stairway the orchestra of colored musicians was
tuning up. Sam, the colored boy, who had first introduced two of the
houseboat girls to Mrs. Preston, was the leader of the band of six
instruments. If you have never heard old-time colored people play dance
music, you can hardly imagine how delightful it is. To-night Sam's
orchestra was composed of six instruments, a bass violin, which he
played himself, two banjos, two guitars and a tambourine.

In the long parlors that were to be used for the dancing Mr. and Mrs.
Preston stood, s