Ned looked back when he had gone a half dozen yards, and already the horses were looming pale and gigantic in the fog.

Three or four steps more and they were gone entirely.
But they heard the sounds again in front of them, although they were now of a different character.

They were confined in one place, which showed that the Mexicans had not resumed their march, and the tread of horses' hoofs was replaced by a metallic rattle.

It occurred to Ned that the Mexicans might be intrenching and he wondered what place of strength they had found.
The boy had the keenest eyes of the three and presently he saw a dark, lofty shape, showing faintly through the fog.

It looked to him like an iceberg clothed in mist, and he called the attention of his comrades to it.