“Take it clean, Hal.  Ready—­go!”

The next instant we were flying headlong through the air toward the surface of the lake a hundred feet below.

Men have told me since that I never made that dive, or that I greatly overestimated the distance, and I admit that as I look back at it now it appears incredible.  Well, they are welcome to their opinion, but I would not advise them to try to argue the matter with Harry.

The impact with the water all but completely stunned me; as I struck the surface it seemed that a thousand cannons had exploded in my ears.  Down, down I went—­lucky for us that the lake was apparently bottomless!

I seemed to have gone as far below the water as I had been above it before I was able to twist myself about and meet it with my belly.  Then, striking out with every ounce of strength in me, I made for the surface as rapidly as possible.  I had started with my lungs full of air, but that headlong plunge had emptied them.

I made the surface at last and looked round for Harry, calling his name.  For perhaps thirty seconds I called in vain, then there came an unanswering shout off to the left.  The urns were far above us now, and the light on the surface of the lake was very dim, but soon I made out Harry’s head.  He was swimming easily toward me, apparently unhurt.

“All right, Hal?”

“Right.  And you?”

“Sound as a whistle.  Now make for the column.”

At the instant that we turned to swim toward the column I became aware of a strong current in the water carrying us off to the right.  It was inexplicable, but there was no time then for speculation, and we struck out with bold, sweeping strokes.

The Incas had left the stone seats and advanced to the water’s edge.  I could see their black, sinister faces, thousands of them, peering intently at us through the dim light, but they made no sound.

Once I cast a glance over my shoulder and saw Desiree standing at the edge of the alcove with her clenched fists pressed to her throat.  Beside her stood the Child of the Sun.  Harry, too, saw her and sent her a shout of farewell, but there was no answer.

We were now less than thirty feet from the column.  Its jeweled sides sparkled and shone before us; looking up, our eyes were dazzled.  Something struck the water near me.  I glanced to the right and saw what moved me to hasten my stroke and call to Harry to do likewise.

The black devils were increasing the fun by hurling stones at us from the bank—­apparently with the kind approval of Pachacamac.

As we neared the column the current which tended to carry us to the right became stronger, but still we seemed not to be approaching the bank.  What could it mean?  The struggle against it was fast taking our strength.

Looking up, I saw that we had swung round to the other side of the column—­it was between us and the alcove.  Then I understood.  We were in a whirlpool, ever increasing in force, which was carrying us swiftly in a circle from left to right and approaching the column.