"I don't know," was Tom's frank answer.

"They do it on an automobile to a great extent," went on Ned.
"Some of 'em you cant hardly hear."

"Yes, but an aeroplane engine runs many, many times faster than
the motor of an auto," said Tom, "and there are more explosions
to muffle. I doubt if the muffler of an auto would cut down the
sound of an aero engine to any appreciable extent. But, of
course, I'll try along those lines."

"They have mufflers or silencers for guns and rifles," went on
Ned. "Couldn't you make a big one of those contraptions and put
it on an aeroplane?"

"I doubt it," said Tom, shaking his head. "Of course it's the
same principle as that in an auto muffler, or on a motor boat--a
series of baffle plates arranged within a hollow cylinder. But
all such devices cut down power, and I don't want to do that.
However, I'm going to solve the problem or--bust!"

And Tom came near "busting," Ned remarked later, when he and
his friend talked over the progress of the invention.

Two weeks had passed since the start of his evolution of his
new idea, and following the visiting of the representatives of
the Universal Flying Machine Company. Since then neither Gale nor
Ware had communicated with Tom.