While Ned continued his search about the interior of the submarine, Frank busied himself inspecting the bits of waste the other boys brought to him. At last an exclamation of astonishment brought Ned to his side.
"There's something funny about this," Frank said, as Ned bent over his shoulder. "That stuff is not oil, and I'd like to know how it got in here."
"What does it look like?" asked Ned.
"I can't say," was the hesitating reply.
Ned took the microscope and looked at the object to which his attention had been called.
"Rubber!" he said, in a moment.
"Rubber!" repeated Frank. "How could rubber be in the waste in that shape?"
"All the same," Ned replied, "this is some rubber composition, and it has been wiped into the waste. Now, what could any person want with rubber here?"
"It is used quite a lot around electric apparatus," suggested Frank
Shaw.
"But not in this form," Ned replied.