How is the hardness of wood measured

We’re all familiar with the terms “hardwood” and “softwood” but have you ever wondered how the hardness of wood is measured? The Janka test calculates the hardness of wood by measuring the force needed to embed a steel ball halfway into a piece of wood. The hardest wood is the Australian Buloke which requires a force of 5,060 lbs to embed the ball and the softest is the Cuipo which requires only 22lbs of force, with the familiar balsa wood being the second softest