“That’s Professor Bumper,” explained Ned.

“How did Valdez get the map out of the professor’s coat?” asked Tom.

“Valdez he very much smart.  When man with no hair on his head take coat off for a minute to eat breakfast Valdez take yellow thing out of pocket.”

“The Indian must have sneaked into camp when we were eating,” said Tom.  “Those from Beecher’s party and our workers look all alike to us.  We wouldn’t know one from the other, and one of our rival’s might slip in.”

“One evidently did, if this is really the piece of oiled silk that was around the professor’s map,” said Ned.

“It certainly is the same,” declared the young inventor.  “See, there is his name,” and he stretched out his hand to point.

“Don’t touch!” cried Tal.  “Poisoned arrows snake poison—­very dead-like and quick.”

“Don’t worry, I won’t touch,” said Tom grimly.  “But go on.  You say Valdez sneaked into our camp, took the oiled-silk package from the coat pocket of Professor Bumper and went back to his own camp with it, thinking it was gold.”

“Yes,” answered Tal, though it is doubtful if he understood all that Tom said, as it was half Spanish and half English.  But the Indian knew a little English, too.  “Valdez, when he find no gold is very mad.  Only papers in the yellow silk-papers with queer marks on.  Valdez think it maybe a charm to work evil, so he burn them up—­all up!”

“Burned that rare map!” gasped Tom.

“All in fire,” went on Tal, indicating by his hands the play of flames.  “Valdez throw away yellow silk, and I take for my arrows so rain not wash off poison.  I give to you, if you like, with blow gun.”

“No, thank you,” answered Tom, in disappointed tones.  “The oiled silk is of no use without the map, and that’s gone.  Whew! but this is tough!” he said to his chum.  “As long as it was only stolen there was a chance to get it back, but if it’s burned, the jig is up.”

“It looks so,” agreed Ned.  “We’d better get back and tell the professor.  It he can’t get along without the map it’s time he started a movement toward getting another.  So it wasn’t Beecher, after all, who got it.”

“Evidently not,” assented Tom.  “But I believe him capable of it.”

“You haven’t much use for him,” remarked Ned.

“Huh!” was all the answer given by his chum.

“I am sorry, Senors,” went on Tal, “but I could not stop Valdez, and the burning of the papers——­”

“No, you could not help it,” interrupted the young inventor.  “But it just happens that it brings bad luck to us.  You see, Tal, the papers in this yellow covering, told of an old buried city that the bald-headed professor—­the-man-with-no-hair-on-his-head—­is very anxious to discover.  It is somewhere under the ground,” and he waved to the jungle all about them, pointing earthwards.

“Paper Valdez burn tell of lost city?” asked Tal, his face lighting up.