Åtvidaberg Sun Cannon
In the town of Åtvidaberg, the midday sun sets off a loud cannon boom.
Åtvidaberg is in southeast Sweden, about 30 miles from the Baltic Sea. It’s a small industrial town, once dominated by copper mining and manufacturing. Today the town is best known for three things: great fishing, fanatical football, and an explosive time keeper—quite literally.
Åtvidaberg’s sun cannon is the only functioning time piece of its kind in the world that still works, and it works every day from the beginning of May through the end of August. The cannon is housed in a small tower on a hill, on the grounds of what used to be extensive estate gardens. When it was built in 1853, these strange cannon-clock devices were common at large estates to help keep track of the time.
It works like this: At midday (or during Daylight Savings Time, 1:00 pm), when the sun reaches its highest point, a lens focuses the sunlight on a small charge of black powder loaded into a 6-pound cannon. Add up some intense sunlight, a little gunpowder, a reasonably sized cannon—and boom! The total is everyone in town knowing it’s time for lunch.
The lens is attached to a movable arm, so it can be adjusted to the sun’s different meridian latitude. But on cloudy days, fear not: the cannon isn’t entirely dependent on solar ignition. On those days the on-duty gunner will manually ignite the charge, so 1:00 never passes in Åtvidaberg unnoticed.
The Atlas Obscura Podcast is a short, daily celebration of all the world’s strange and wondrous places. Check out this episode about the Åtvidaberg Sun Cannon.
Know Before You Go
Åtvidaberg is in southeast Sweden, about 135 miles (a two and a half hour drive) from Stockholm. There are signs to the cannon tower, which is just a few minutes from the center of the town. It’s located on the Kanonkullen Hill, next to Lake Bysjön. Parking lots are available next to the soccer field, and from there it's just a short walk up the hill. Be sure to get there around 12:45pm, 15 minutes before the cannon is fired, to get to hear some of its history. You can also make arrangements to fire the sun cannon yourself, under the guidance of the tower's gunner. If you do, you'll get a diploma certifying you as a official Sun Cannoneer.
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