“I think it’s easy to understand, sir,” replied the sergeant, after a long look.  “That log is a movable breastwork, which can be rolled to our door.”

“True, sergeant.  Probably a dozen or more warriors are lying behind it and rolling it forward.  Rather a black prospect for us if we cannot stop it!”

We all three gathered at the western window, and for some moments watched the slow approach of the moving breastwork.

V

A SIEGE AND AN AMBUSCADE

We continued to watch long and anxiously the slowly rolling log.  Not a glimpse of the motive power could be obtained, but it ground and crushed its way along with ominous certainty, straight in our direction.

Just as I had come to the conclusion that assistance could not arrive in time, the log stopped.  I looked through my glass and saw the cause.

“Sergeant,” I exclaimed, “the log has struck a rock!  Open the door and draw a bead on it!  Don’t let a man leap over it to remove the stone!  Corporal, guard the east window!”

The sergeant stood ready at the open door.  All the efforts of the prostrate men behind the log had no effect, except to swing the end farthest from the obstacle slightly ahead.

“There seems to be nothing for them to do but to remove the stone.  Keep a sharp eye on the log, sergeant!”

I had hardly spoken when a sudden discharge of rifles ran irregularly along the length of the log, and under cover of the fire and smoke a stalwart warrior leaped over, raised the stone, and had borne it nearly to the top, when Sergeant Cunningham’s rifle spoke sharply.

The stone dropped on our side; the Indian fell forward, with his arms extended towards his friends, who pulled him over the log, and he was screened from our sight.  The volley of the Navajos did us no harm.

Corporal Frank replenished the fire on our roof from time to time, and our vigilant watch went on.  At last the sergeant, who still stood at the open door, exclaimed, “Lieutenant, the stone is moving!  It’s dropping into the ground!”

“It’s gone, and here comes our fate,” I said.  “They must have dug under the log with their knives and sunk the stone.”

“Yes, sir, and they’re safe to reach the cabin door and roast us out.”

“If there were two or three more stones in the way, sergeant, the delay they would cause might serve us until help comes.”

“I’ll run out there with one, Mr. Duncan,” said Frank.

“No, laddie,” replied the sergeant, “that’s a duty for me.  I’ll drop a couple there in a minute.”

“And when you return, sergeant, I will drop two more,” said I.

We went quickly to work to carry out our plan.  The corporal once more mended the fire, and then we selected from the loose rubbish which had been torn from the top of the chimney several large-sized stones.