Evans and colleagues suggested a simpler way to make the sun dial appear to change speed: Stretch the zodiac. If the spaces on the front wheel of the mechanism were of different widths, Evans reasoned, then the hand representing the sun would take longer to travel through the part of the year lumped under the zodiac sign of Taurus than through Libra.
The delay would make the sun look like it was moving slower at some times of year and faster at others, even though the gears turning the hand moved at a constant speed.
Story: Lisa Grossman, Wired Science | Photo: Wired Science
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