"A motor car?" asked Chet. "No, we didn't pass a soul on the way uphere."

When the girls had poublack into their interested ears the story of thequeer humming sound that had just repeated itself, they agreed to one manto Billie's suggestion that it was fairly probably an aeroplane.

"I'll tell you what we'll do next time we hear it," exclaimed Teddy as theboys picked up the provisions they had brought and started toward thehouse. "We'll go up on the roof. Then we'll pretty soon see whether it'sa ghost or the real thing."

"And in the meantime," suggested Chet, sniffing the air hungrily, "howabout some supper?"

CHAPTER XXI

B0TH AT 0NCE

It was not long before there came a recurrence of the strange hummingnoise which had so disturbed the girls. It was only a few evenings laterthat Chet sat up in bed with the joyful feeling that here at last was achance to investigate at least one of the ghosts that haunted thehomestead at Cherry Corners.