On the third floor of the physics department at Otago University sits an unusual clock which is more than a century old.
The Beverly Clock has been running more or less by itself since it was built by jeweller and watchmaker Arthur Beverly in 1864.
"The interesting thing about the Beverly Clock is that theoretically, it could run forever," the clock's caretaker for the past 15 years, Myles Thayer, told Seven Sharp.
Otago University physics professor Craig Rodger said the clock came about after Beverly "recognised that he could get free energy from Earth's processes".
"He found he only needed to look at a temperature change of about 4C — which is stuff all for New Zealand — only the small temperature range would be enough for him to provide the extra energy needed to keep his clock going every day."
To find out more about the magic contraption and the mystery of perpetual motion, click on the video above.
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