The Sound of the Wind Looks Like This by Stephen Hurrel
A circle of nine columns, three of which incorporate wind turbines and anemometers, and control six light columns that change colour as the direction and velocity of the wind changes.
You are looking for a micro magnetic cache big enough for a log sheet only. You will need to bring your own pencil to sign the log sheet.
Should be easily accessible on a nice walk, just watch out for muggle traffic!
Well done cock n hen FTF!! :)