bussola

Bussola, a term used in Italian and Portuguese (bússola in Portuguese; bussola in Italian), refers to a device that indicates direction and aids navigation. The most common form is the magnetic compass, which uses a magnetized needle or rotating card that aligns with the Earth’s magnetic field to point toward magnetic north. In modern devices, electronic sensors and gyroscopes are also used to determine direction.

Construction and operation: A traditional magnetic compass consists of a free-moving magnetized needle balanced on a pivot, inside a sealed case with a graduated dial. In maritime versions, a gimballed binnacle and damping fluid stabilize the needle. The compass card is marked with bearings in degrees, allowing navigators to determine headings relative to magnetic north.

Magnetic versus true north: Magnetic north differs from geographic (true) north, so navigators apply magnetic variation (declination) from local charts or adjust readings to obtain true headings. Deviation caused by nearby metal objects or equipment must also be accounted for in precise navigation.

History and variants: The compass originated in China and spread to the Arab world and Europe by the Middle Ages, playing a central role in maritime exploration. Beyond the magnetic compass, other variants include the gyroscopic (or north-seeking) compass and electronic compasses that rely on magnetometers to determine direction.

Modern usage: Today, compasses are used in navigation, surveying, orienteering, aviation, and in smartphones and vehicles that integrate magnetometers, GPS, and inertial sensors to provide directional information. The term “bussola” may appear in Italian and Portuguese texts to denote this instrument.