1780: "The Hoover Dam Angels"

0:00On the Nevada side of the Hoover Dam, two enormous bronze figures stand with their wings reaching to the sky. Visitors, they rub their toes for good luck before heading to Las Vegas, polishing the bronze to a golden shine. Officially called the Winged Figures of the Republic, they were created by Norwegian-born sculptor Oscar Hansen. Each one stands 30 feet tall and contains more than four tons of bronze. Casting them, it required 492 tonne sand molds and molten bronze heated to 2500 degrees Fahrenheit, all poured in one continuous motion, one solid operation. Their polished black stone bases presented a totally different challenge. Workers, they lowered massive blocks onto slabs of ice, allowing them to settle into position as the ice melted, without scratching the stones.

1:01Hansen also designed the dams art deco-reliefs and a memorial plaque honoring workers who died during the construction. But beneath the figure's lies his most unusual design. The Taras of Floor contains a celestial chart, recording the positions of the stars and planets on September 30, 1935, the day President Franklin Roosevelt dedicated Hoover Dam. Working with the Smithsonian Institute and the U.S. Naval Observatory, Hansen reportedly performed more than 200,000 astronomical calculations. He accounted for the precision of the equinoxes, the slow wobble of Earth's axis that completes the cycle approximately every 26,000 years, gradually changing which star serves as the North Star. The chart was intended to allow someone thousands of years in the future to determine the dedication date, even if written record disappears.

2:02Hansen considered Hoover Dam an achievement comparable to the ancient pyramids. He wanted future civilizations to know when it was built using the movement of the heavens rather than relying on a language that they may not understand. And nearly a century later, visitors continued rubbing those toes, often unaware that the floor beneath them was designed to communicate with people thousands of years in the future. These are interesting things with J.C.