n suddenly, and
with a groan, it seemed to drop into the earth, and all was darkness
once more. The boys clung one on each side to the doctor, who trembled
hardly less than themselves. No one dared move, or speak, or utter a
sound.

Again the moon sent forth a beam, as the figure once more appeared and
slowly rose higher and higher. For a moment it seemed as if it would
soar into the air, but again with a dull crash it descended and
vanished.

"Boys," said the doctor hoarsely, "I confess I--I am puzzled!"

"I--I wonder," said Dell, "if I ever dare go and see what it is. I say,
M-m-organ, would you g-g-go with me--for the d-d-doctor's sake?"

"Oh, Dell! I'm afraid. But--yes, I'll try."

"Brave boys!" said the doctor, never taking his eyes off the spot where
the ghost last vanished.

The two boys stole forward on tiptoe, holding one another's arms; then
suddenly they broke into a rush straight for the sign-post.

There was a loud shriek as the white figure rose up to meet them.

"Bilk, you idiot, cut back for your life! here's the doctor! We were
only having a lark with you. Do cut your sticks, and slip in quietly,
and it'll be all right. Look alive, or we're all three done for!"

The ill-starred Bilk needed no further invitation. He started to run as
fast as his long legs would carry him, his night-gown flapping in the
evening breeze, and his two persecutors following him with cries of
"Booh!"

"Scat!"

"Shoo!" and other formulae for exorcising evil spirits.

After a hundred yards or so the two heroes gave up the chase, and
returned to the slowly-reviving doctor.

"Come along, sir," said Dell; "there's nothing there; it vanished as
soon as we got to it. Let us be quick, sir, in case it comes back."

The remainder of the walk home that evening, I need hardly observe, was
brisk; but it was not so brisk as the same journey accomplished by
Alexander Magnus Bilk, who had reached the school a full quarter of an
hour before his pursuers, and was safe between his blankets by the time
that they peeped into his room on their way to bed, and whispered
consolingly, "It's all up with the duke's daughter now, old man!"

The doctor may have had some dim suspicion of the real state of affairs;
but if so, he gave no sign, and the boys, happy in their escape from
what might have proved a grave matter, were content to forego all
further practical jokes of the kind for the rest of the session.

CHAPTER THI