Compass

A compass, also called a trailfinder, was an instrument that showed the cardinal directions. It was used for navigation and travel. They were found amongst sets of cartographer's tools and navigator's tools.

Function
Compasses utilized a magnetic needle that pointed north–south, but the principle was not well understood in the Realms, so their designs were crude and unscientific. For example, although navigators around Zakhara in the mid–14 century DR were familiar with them, it was widely believed the needle was possessed by a gen. In addition, navigators did not fully understand magnetic declination, that is, the angle of difference between a magnetic pole and a pole star. Hence, their accuracy was passable and their usefulness limited, and made much worse aboard a rocking ship, yet they could still provide a slight benefit to navigation at sea.

Magical compasses also existed in Zakhara that really did have a gen trapped in the needle, and these were incredibly rare and just as expensive. However, these pointed always to the pole star, not to magnetic north, so they had a significant discrepancy with basic compasses, which could cause confusion. They remained much more accurate and were a greater aid to navigation.

Zakharan compasses had thirty-two points of direction. Each was called a khann.

Proximity to large lodestone—that is, magnetic rock—could ruin a compass needle.

Usage
Compasses were used for navigation in such places as the Sea of Fallen Stars in Faerûn, the Celestial Sea in Kara-Tur and the Crowded Sea of Zakhara.

Trailfinders were used in the Utter East during the Bloodforge Wars (648–657 DR) to aid basal golem warriors traverse uneven terrain.

History
Compasses were invented, at least independently, by Shou craftsmen of Shou Lung.

Appearances

 * Blood & Magic
 * ''Idle Champions of the Forgotten Realms