Perpetual Calendar of Giovanni Antonio Amedeo Plana

Want to know the day of the week that the Western Roman Empire fell to the barbarians, on September 4, 476? This device, built by astronomer and mathematician Giovanni Antonio Amedeo Plana in 1831, will give you the answer (it was Monday). The Perpetual Calendar, which took 10 years to complete,  operates via a simple wooden crank that hides a stunningly accurate universal mechanical calculator spanning the years 1 to 4,000.

The Perpetual Calendar features windows that show key dates and moon phases for 4,000 years. ECCEKEVIN/WIKIMEDIA/CC-BY-4.0


A team of three students from the Polytechnic University of Turin spent months unraveling the device’s mysteries.

Read more: Atlas Obscura

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