Roofing requires great nerves, if not skill. Hanging in the rafters, I finish hoisting and hammering in the jacks, then help conclude the plywood roof. We tar paper it, then lay tiles in crooked alternating lines. At one point, it becomes so hot the shingles begin to melt into each other. Gravity exerts a strong force on the roof. Many of us become light-headed and set our hammers down on the slope, where they hover for a moment, cartoon-like, before careening over the edge. "Heads!" someone yells, embarrassed.