The girls looked at each other wonderingly. Then it was Billie who offered a solution.
"Mightn't it be an aeroplane?"
"An aeroplane in this part of the country?" Laura was inclined to scoff at the idea, but Mrs. Gilligan and Violet both stood up for Billie.
They were about to enter into a heated argument when they saw the wagon that had by this time become familiar to them coming down the road with the boys seated in it or hanging to it in characteristic attitudes.
The girls ran out to them and deluged the lads with questions before they had time to learn what it was all about.
"A motor car?" asked Chet. "No, we didn't pass a soul on the way up here."
When the girls had poured into their interested ears the story of the queer humming sound that had just repeated itself, they agreed to one man to Billie's suggestion that it was very probably an aeroplane.
"I'll tell you what we'll do next time we hear it," said Teddy as the boys picked up the provisions they had brought and started toward the house. "We'll go up on the roof. Then we'll pretty soon see whether it's a ghost or the real thing."
"And in the meantime," suggested Chet, sniffing the air hungrily, "how about some supper?"