private fun enable_magnetic_field
	do
		magnetic_field.asensor = sensormanager.get_default_sensor(new ASensorType.magnetic_field)
		if magnetic_field.asensor.address_is_null then
				print "Magnetic Field unavailable"
		else
			if eventqueue.enable_sensor(magnetic_field.asensor) < 0 then print "Magnetic Field enabling failed"
			eventqueue.set_event_rate(magnetic_field.asensor, magnetic_field.event_rate)
		end
	end