By the power vested in us, it is decreed that all compasses shall be used as magnetometers from this day forward.
This edict is not negotiable. All compasses shall henceforth be employed for their original purpose: to measure the earth's magnetic fields.
Compass users who fail to comply shall be subject to the wrath of the Webmaster.
Sub-decree 1: Compass-as-Magnetometer Implementation Guidelines
Sub-decree 2: Compass-as-Magnetometer Penalties
The ultimate tool for magnetometry. Don't try to use it as a compass. Don't even think about it.