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."
 
"Oh, then you have had it since last night!" Tom ejaculated.
 
"Yes, I slept with it under my clothes that I rolled up for a pillow, and when it was my turn to stand guard I took it with me. Then I put it back again and went to sleep. When I awoke and dressed I put the packet in my pocket and ate breakfast. Now when I look for it—why, it's gone!"
 
"The map or the oiled-silk package?" asked Mr. Damon, who, once having been a businessman, was sometimes a stickler for small points.
 
"Both," answered the professor. "I opened the silk to tie it more smoothly, so it would not be such a lump in my pocket, and I made sure the map was inside."
 
"Then the whole thing has been taken—or you have lost it," suggested Ned.
 
"I am not in the habit of losing valuable maps," retorted the scientist. "And the pocket of my coat I had made deep, for the purpose of carrying the long map. It could not drop out."
 
"Well, we mustn't overlook any possible chances," suggested Tom. "Come on now, we'll search every inch of the ground over which you traveled this morning, Professor."
 
"It MUST be found," murmured the scientist. "Without it all our work will go for naught."
 
They all went into the tent where the professor and Mr. Damon had slept when they were not on guard. The camp was a busy place, with the Indians finishing their morning meal, and getting ready for the work of the day. For word had been given out that there would be no more long periods of travel.
 
In consequence, efforts were being directed by the head men of the bearers to making a more permanent camp in the wilderness. Shelters of palm-thatched huts were being built, a site for cooking fires made, and, at the direction of Mr. Damon, to whom this part was entrusted, some sanitary regulations were insisted on.
 
Leaving this busy scene, the four, with solemn faces, proceeded to the tent where it was hoped the map would be found. But though they went through everything, and traced and retraced every place the professor could remember having traversed about the canvas shelter, no signs of the important document could be found.
 
"I don't believe I dropped it out of my pocket," said the scientist, for perhaps the twentieth time.
 
"Then it was taken," declared Tom.
 
"That's what I say!" chimed in Ned. "And by some of Beecher's party!"
 
"Easy, my boy," cautioned Mr. Damon. "We don't want to make accusations we can't prove."
 
"That is true," agreed Professor Bumper. "But, though I am sorry to say it of a fellow archaelogist, I can not help thinking Beecher had something to do with the taking of my map."
 
"But how could any of them get it?" asked Mr. Damon. "You say you had the map this morning, and certainly none of them has been in our camp since dawn, though of course it is possible that some of them sneaked in during the night."
 
"It does seem a mystery how it could have been taken in open daylight, while we were about camp together," said Tom. "But is the loss such a grave one, Professor Bumper?"
 
"Very grave. In fact I may say it is impossible to proceed with the excavating without the map."
 
"Then what are we to do?" asked Ned.
 
"We must get it back!" declared Tom.
 
"Yes," agreed the scientist, "we can not work without it. As soon as I make a little further search, to make sure it could not have dropped in some out-of-the-way place, I shall go over to Professor Beecher's camp and demand that he give me back my property."
 
"Suppose he says he hasn't taken it?" asked Tom.
 
"Well, I'm sure he either took it personally, or one of his party did. And yet I can't understand how they could have come here without our seeing them," and the professor shook his head in puzzled despair.
 
A more detailed search did not reveal the missing map, and Mr. Damon and his friend the scientist were on the point of departing for the camp of their rivals, less than a mile away, when Tom had what really amounted to an inspiration.
 
"Look here, Professor!" he cried. "Can you remember any of the details of your map—say, for instance, where we ought to begin excavating to get at the wonders of the underground city?&quo............