By this time I had begun to feel pretty well exhausted, and when I suddenly thought of the undertow, I decided to swim back.
So intent had I been upon urging Nab near enough to get the lariat about his neck that I had not once looked toward shore. As I now did so I was terrified to find that one of the unaccountably shifting currents along Moss Beach had swept me a long distance out to sea.
Without more nonsense, I dropped my remaining shad and started back with long, even strokes. Nab snapped up the fish and disappeared in the deep green water.
In spite of my efforts, I found that I was making small speed against the current. The rock and tree on the point of land to my right, by which I judged my progress, kept almost in the same straight line. Knowing it was useless to spend my strength directly against a current, I shifted my course in the direction of the point. From the sand-hills to my left I could see that I now made more progress, but the distance I had to cover was greater than straight to Moss Beach.
Before I had covered half the distance I was almost too fatigued to take another stroke; then the feeling of weariness seemed to leave me, and I swam on as if turned into a machine. It was in a mechanical way, too, that my brain seemed to work.
"If the undertow's as strong as when I came out," I thought, "I can never get through the breakers."
I wished I had told father my plans. He might have come out with a boat to get me. Then I wondered how it was that my arms and legs kept on moving when there was so little feeling in them.
The roar of the breakers had suddenly grown louder, and I saw I was within twenty yards of shore. I swam on with the same steady strokes, but at a certain distance from the water-line came to a standstill.
I knew I was held back by the undertow, and that there was need of all my remaining strength to get ashore. I increased my efforts, but surged helplessly forward and backward with the rising and falling waves.
When I thought I had given my last stroke, a big wave boosted me in, followed by a second and third, until it seemed I must be where I could reach bottom.