“At what point?” asked Tom.

“At a point I shall indicate after a further consultation of the map.  I must see the configuration of the country by daylight to decide.  And now let’s get some rest.  We have had a hard day.”

The two tents housing the four white members of the Bumper party were close together, and it was decided that the night would be divided into four watches, to guard against possible treachery on the part of the Beecher crowd.

“It seems an unkind precaution to take against a fellow scientist,” said Professor Bumper, “but I can not afford to take chances after what has occurred.”

The others agreed with him, and though standing guard was not pleasant it was done.  However the night passed without incident, and then came morning and the excitement of getting breakfast, over which the Indians made merry.  They did not like the cold and darkness, and always welcomed the sun, no matter how hot.

“And now,” cried Tom, when the meal was over, “let us begin the work that has brought us here.”

“Yes,” agreed Professor Bumper, “I will consult the map, and start the diggers where I think the city lies, far below the surface.  Now, gentlemen, if you will give me your attention——­”

He was seeking through his outer coat pockets, after an ineffectual search in the inner one.  A strange look came over his face.

“What’s the matter?” asked Tom.

“The map—­the map!” gasped the professor.  “The map I was showing you last night!  The map that tells where we are to dig for the idol of gold!  It’s gone!”

“The map gone?” gasped Mr. Damon.

“I—­I’m afraid so,” faltered the professor.  “I put it away carefully, but now——­”

He ceased speaking to make a further search in all his pockets.

“Maybe you left it in another coat,” suggested Ned.

“Or maybe some of the Beecher crowd took it!” snapped Tom.

CHAPTER XVIII

“El tigre!”

The four men gazed at one another.  Consternation showed on the face of Professor Bumper, and was reflected, more or less, on the countenances of his companions.

“Are you sure the map is gone?” asked Tom.  “I know how easy it is to mislay anything in a camp of this sort.  I couldn’t at first find my safety razor this morning, and when I did locate it the hoe was in one of my shoes.  I’m sure a rat or some jungle animal must have dragged it there.  Now maybe they took your map, Professor.  That oiled silk in which it was wrapped might have appealed to the taste of a rat or a snake.”

“It is no joking matter,” said Professor Bumper.  “But I know you appreciate the seriousness of it as much as I do, Tom.  But I had the map in the pocket of this coat, and now it is gone!”

“When did you put it there?” asked Ned.

“This morning, just before I came to breakfast.”