In a city shy of skyscrapers, super-ferris wheel London Eye rises 40 stories above the Thames. 800 riders in 32 lounge-sized pods hang of its rim. So finely balanced, the machine never stops while loading and unloading passengers. The high-powered Samba is a jet ski prototype with a redesigned hull profile that races over the water. It also responds to the low-slung rider's body moves, spinning a full one hundred and eighty degrees at an almost standstill. Hoover Dam is a giant machine that uses water pressure to drive turbines that produce electricity - simple in theory. But in practice, the real work is holding back a raging river to create enough water pressure at bone-crushing depths. The traffic light is the visible end of a machine-like, coordinated web designed to keep urban people and traffic in synchronized motion. The modern intersection actually reads traffic patterns, and adjusts its signals in real time.