He pushed her away and without another glance in her direction, attacked the safe. It was built into the structural steel of the hull, a massive steel ball some four feet in diameter. It was welded to the strakes and ribs of the "Nomad" at twelve different spots. Foyle attacked each weld in turn with acids, drills, thermite, and refrigerants. He was operating on the theory of structural strain... to heat, freeze, and etch the steel until its crystalline structure was distorted and its physical strength destroyed. He was fatiguing the metal.