CHAPTER X.
EXPLORING AROUND THE LAKE.
If Dick and Doctor Dan expected to see a new monster come up out of the lake that was the time they got left.
Charley said from the first that nothing was coming and he was right.
“It’s not old P. D.,” he declared; “that isn’t the way he boils the pot.”
Doctor Dan looked a bit puzzled.
“Might I inquire,” he asked in his stately way, “what you mean by old P. D.?”
“Why, certainly,” replied Charley. “Life is altogether too short to say Plesiosaurus Dolichodeirus every time and even Plesiosaurus without the doli-what’s-its-name takes too long, so from this time on I shall speak of our rubber-necked friend as old P. D.”
“Exactly,” said Doctor Dan. “Now that I know I shall remember. I am not familiar with the scientific names of these monsters. I expect to see something. Watch! It will come. On this very spot Ike Izard and I saw the water boil like this.”
“And nothing came of it?” asked Charley.
“Nothing then. The monster did not rise.”
“No, nor no monster will rise this time,” said Charley, emphatically. “You’ll see.”
“I think I know what you are driving at,” said Dick. “You are thinking of the underground lake we talked about.”
Charley nodded.
Doctor Dan looked puzzled, not understanding what that had to do with the boiling of the water which still continued.
They watched the troubled surface of the lake for several minutes.
The boiling grew less and less until finally it ceased altogether, nothing having appeared.
“There you are,” said Charley, triumphantly. “Just as I said.”
“Your idea is, I suppose,” said Dick, “that the water is running off into the underground lake?”
“My idea is,” said Charley, “that under the mountain on the left here is a big cavern at a lower level than this lake and that between it and the lake is a deep hole. When the hole is full of water it discharges into the cavern gradually by a small outlet, when it gets down to a certain level the water of Izard Lake runs down into the hole until the equilibrium is restored.”
“Right,” said Dick. “Just what I think, exactly.”
“It’s too deep for me,” said Doctor Dan, shaking his head.
“What, the theory or the hole?” laughed Dick.
“Both. I should have to see the hole before I believed in it and I don’t understand the theory of all.”
“If we could only stay here and watch we would find that the boiling takes place at regular intervals and continues just so long,” added Charley. “We can investigate this later on if you say so, Dick.”
“By all means,” replied Dick, “but now we must be on the move. I shall never rest until I have found Clara Eglinton and I only hope Doctor Dan’s theory proves correct.”
“About the horse?” replied Doctor Dan. “You will find it entirely correct. If I am not up on science I am on horses. Give that mare her head and she will take us to the place where they turned off with the lady sure; that is, if there is any such place. As I understand the situation, you are not actually sure that Mudd captured her at all.”
“Well, I have only his word for it,” said Dick, “and that don’t amount to much, I own.”
They now moved on. The mare led the way into the pass through which Dick had come, continuing along about half the distance to the trail up the mountain, when she suddenly turned and stopped short up against the solid ledge.
“Well!” exclaimed Doctor Dan, “this is queer!”
The place into which the mare had turned was a sort of niche in the rocky wall, crescent shaped and perhaps forty feet deep.
There was no break anywhere and the rocks towered to a height of several hundred feet above their heads.
“What’s the matter with the beast? What does she stop here for?” demanded Dick.
But Doctor Dan could give no satisfactory answer to this question.
He dismounted and made a long and careful examination of the place without discovering anything to explain the conduct of the mare.
“It beats me,” he said at last, “but one thing is certain there is no way through that ledge.”
“Perhaps they just halted here for some purpose or other,” said Dick. “I think we had better push on. The mare may give us another steer.”
But the mare did nothing of the sort. They continued on to the trail and then down the mountain to the alkali plains.
Doctor Dan’s knowledge of the country came in play here, for he recognized the place and led the way to their old trail up the mountain, which began about half a mile further along.
It seemed useless to spend any more time then looking for Clara Eglinton, so they continued on to the camp, where Doctor Dan cooked a splendid breakfast, having shot an antelope just before they turned off from the plain.
The remainder of the day passed without any notable adventure.
In the afternoon the rubber boat was launched again and Dick and Charley pulled across the lake to the hut, leaving Doctor Dan to go on an exploring expedition along the shore on his own account.
The hut was still deserted and there was no sign that Mudd and his companions had returned.
The boys on the way back pulled around to the place where the singular boiling of the water had occurred.
All was placid enough now, but just as they were turning away the boiling began again.
The boys watched it until it ceased, the time being exactly ten minutes.
After it was over they waited around for half an hour more, but the phenomenon was not repeated.
“We must come over and spend the day here soon,” declared Dick. “My theory is that if an underground lake really exists that is where old P. D. and the other monster have their holdout and we must contrive some way to get down into it. Maybe the underground passage I went through connects with your cavern, Charley. What do you say to following it up and trying to find out?”
“That’s the idea, exactly,” said Charley. “We know from your discovery that there is a small underground lake, so what’s to hinder there being a big one? We’ll take that in to-morrow and the event will prove that I am right.”
On the way back to camp Charley thought that he caught sight of the head of old P. D. lifted for a single instant above the water, but Dick did not see it and Charley could not feel quite sure.
When they got back to camp they found that Doctor Dan had already returned and had supper ready.
“I’ve got great news to tell you, boys,” he exclaimed. “I’ve seen old P. D. again and this time on the land. What do you say to that?”
“Hooray!” cried Dick. “Here’s another discovery of the habits of old P. D. It gives me hope that we may succeed in capturing him yet.”
“There’s a chance for us,” said Doctor Dan, “and I can show you just how it can be done if you will follow me around the lake shore to a place where I was to-day.”
He had scarcely made the remark when the same old bellow was heard off on the lake.
All hands ran down to the shore and looked off upon the water, but not a thing could they see of old P. D.