From the article:
The general design is shown to the left. It is a bowl which is a segment of a sphere suspended on a tripod which runs through holes in the bowl. In the bowl is a flat fire-grate made of expanded metal which holds the fire off the base of the bowl, keeping it cool and allowing a place for ashes to fall. The tripod additionally supports the grill on which you cook, or can be used to suspend a pot above the fir. The bowl is constructed of six fan-shaped plates which pivot on a central bolt and latch together with hooks to form a rigid structure. The fans are overlapped so that there are no open gaps through which coals might fall to the ground.