After a few minutes I got my breathing under control and my lungs cleared of water and, best of all, my heart stopped hammering like a mad blacksmith pounding hot iron which, incidentally, is what my chest felt like.
“What happened?” Hermes wanted to know. He’d just saved my life, but then, that was his job. His expression was decidedly odd and I took that to mean he was relieved that I was alive, but there was something more to it. He looked amused. I looked around at the other men and they were all trying to hide smiles, unsuccessfully. One began to chuckle, then they all chuckled, then roared with laughter.
“Let me in on the joke,” I said in my deadliest voice.
“P-Praetor,” said one when he could talk. “If you could have heard the sound you made just before you went under!”
“And the look on your face!” said another. Then they were all off laughing again.
“I can only regret,” I said, “that I didn’t drown and make your mirth complete.” This set them rolling on the floor. Hermes, too. True, they had saved my life, but there is such a thing as carrying gratitude too far. I waited until they returned to sanity. I needed the time anyway, to get my breath under control.
“What did happen?” Hermes asked at length.
“Something I should have anticipated. I’m no aqueduct engineer, but I know a little about how water moves. The tunnel where the water comes in is almost man-height and just as wide. Where it goes out is a tunnel not one-fourth as large. Yet the level of the water here in the cave stays the same. How can that be?”
“The same amount flows out as flows in?” Hermes hazarded.
“Precisely. And how does it do that?”
He thought for a moment. “It has to flow out a lot faster than it flows in.”
“That is right. Just as when a river flows through a narrow canyon. At the spot it enters, the water speeds up and foams and rapids form. Same here. The current is strong coming in, and it has terrible force going out. I should have been more cautious. So you found nothing else?”
“Nothing, Praetor,” reported one of the men.
“Very well. Let’s get out of this place.”
Hermes and I resumed our clothes and we began the trudge back to the surface. “Do you think we’ve learned anything?” he asked. “Other than to watch out for fast water?”
“I think we have. It may not be apparent just yet, but we know more of that cave than we knew before, and when we know a little more, these things may fall into place.”
“I hope so,” he said. “At least we’re through wandering underground.”
“No, we are not,” I told him. “Now we’re going to do the same thing with the other tunnel.” Hermes groaned. So did the others. Now it was my turn to smile. Laugh at me, would they? We’d see about that.
At least the priests of the Temple of Apollo were all dead and didn’t try to hinder us. I got a good close look at the trapdoor first. There were what appeared to be bloodstains on its underside. I thought about this for a while, then I realized what I was looking at.
“Hermes, you remember when we found the bodies of the priests and their hands and forearms were battered?”
“Yes, we figured they’d been defending themselves from their attackers.”
“We were wrong. They were bashing their fists against this stone, trying to get out after it had been shut behind them.”
He thought about the implications of this. “Then we’re back to the possibility that there was just a single killer. Let them suffocate down there, then dispose of the bodies afterward at your leisure.”
“That is how I see it. I suspect there was more than one, but it was certainly an easier task than it appeared at first.”
Next we examined the tunnel, and I left a man to guard the trap with drawn sword to make sure that it stayed open. I had no desire to emulate the example of the late priests. The tunnel told us nothing at all. The smooth-dressed stone would have revealed any irregularities immediately and there were none.
The chamber below was no better. It looked no different than it had before, except for the absence of corpses. As before, the air quickly grew close from our profusion of torches and lamps and our own exhalations.
“Greeks are supposed to know everything,” Hermes said. “Why didn’t they think to provide ventilation, when those Aborigines thousands of years ago did?”
It was a good question. “Maybe,” I said, “they didn’t think it would be needed. A small number of men don’t require a lot of air if they’re only going to be down here a short time, and with the trap above open, it isn’t too bad.”