At Montpelier he had procured six large pieces of iron, about eighteen inches long, with a gimlet at one end of each, and a square at the other, which fitted to a handle which unshipped.

For precaution he had a spare handle, but each handle fitted to all the irons.

O'Brien had screwed one of these pieces of iron between the interstices of the stones of which the wall was built, and sitting astride on that, was fixing another about three feet above.

When he had accomplished this, he stood upon the lower iron, and supporting himself by the second, which about met his hip, he screwed in a third, always fixing them about six inches on one side of the other, and not one above the other.

When he had screwed in his six irons, he was about half up the wall, and then he fastened his rope, which he had carried round his neck, to the upper iron, and lowering himself down, unscrewed the four lower irons: then ascending by the rope, he stood upon the fifth iron, and supporting himself by the upper iron, recommenced his task.