A very ordinary placement (may be wet at times), a difficult puzzle for some (me included).
Scientific caclulator needed.
Pendulums are interesting devices.
If you set a pendulum in motion at the north pole, the Earth will turn counter-clockwise under it 360 degrees in 24 hours. Thus the pendulum precesses clockwise a full circle in 24 hours.
At the equator, a pendulum will simply go back and forth with no precession.
At 30 degrees north, the pendulum will precess 360 degrees in 48 hours.
Thus, via a pendulum, you can in fact determine your latitude anywhere on Earth!
At the poles a pendulum will actually precess 360 degrees in 23.93 hours, a sidereal day. For simplicity sake I will use the common solar day (as some sites do) of 24 hours for our calculations.
FUN STUFF AT THE SOUTH POLE
The above coordinates for latitude are bogus, but the longitude is correct.
A pendulum at this latitude will precess 360 degrees in 32 hours 27 minutes and 25.28038050003271040213838561856 seconds. animated example
Find the correct latitude, find the box. Small clear lock-n-lock.