Also known as a Maine weather stick , the weather stick is a balsam fir ro, generally about 40cm (16") long which when mounted outside twists upward with the onset of good weather and downward as inclement weather approaches. These sticks were first used by the aboriginals of the American northeast and the Canadian east and southeast, who noted the behavior of dry branches prior to the arrival of weather changes. The weather stick is a rare example of a weather prediction tool which predates the mercury barometer.