what mechanics make the beast seem alive when the boys find it?

"So the figure, with feet that dragged behind it, slid up the mountain. Yard by yard, puff by puff, the breeze hauled the figure through the blue flowers, over the boulders and red stones, till it lay huddled among the shattered rocks of

the mountain-top. Here the breeze was fitful and allowed the strings of the parachute to tangle and festoon; and the figure sat, its helmeted head between its knees, held by a complication of lines. When the breeze blew,the lines would strain taut and some accident of this pull lifted the head and chest upright so that the figure seemed to peer across the brow of the

mountain. Then, each time the wind dropped, the lines would slacken and the figure bow forward again, sinking its head between its knees. So as the stars moved across the sky, the figure sat on the mountain-top and bowed and sank and bowed again."