Just before sunset one day last week, cool John Cobb of London squeezed his 200 lbs. into the cockpit of his two-engined, ice-cooled racing car. It was his last chance of the year: the rainy season was at hand on Utah's Bonneville salt flats. The cowling was bolted into place on top of him; a truck gave the car a push. At 20 m.p.h., the engine coughed and then settled into a steady roar. At 140 m.p.h., Cobb shifted into second gear, into high at 240 m.p.h. About halfway down the 14 mile course he entered the measured mile. Cobb, a...

