The Antikythera Mechanismis the earliest bronze geared device ever found. Each of its 30 gears has between 15 and 223 triangular teeth. Turninga knob on the side of the mechanism would have engaged the largest wheel, which rotated once for every year. Other gears governed the sun, moon, planets, and the pointers on two calendrical spirals. A CT X-ray image, right, reveals complex inner workings of the mechanism heretofore hidden beneath its corroded surface, above. www.archaeology.org 43http://www.archaeology.org