In modern understanding, any device that indicates direction can be considered a compass. Until the late 19th century, these included devices indicating direction using alignment with the Earth’s magnetic field (Magnetism), e.g. magnetic needles freely suspended from a wire, piercing a piece of straw floating in water, or balanced on a pivot inside a box. The ubiquitous presence of iron-rich, permanently magnetised minerals (usually called lodestones) enab…