Current Holder: Adrien_de_Montferrand

Origin: Constructed by Adrien de Montferrand, originally for geological survey work

Description

A small brass instrument of Adrien’s own design, roughly the size of a pocket watch. A needle is mounted on a central pivot inside a glass-faced housing. The device was originally built to detect sub-audible vibrations in stone for geological survey work. Adrien demonstrated it by placing it near a tuning fork: the needle swings toward sources of resonant frequency.

In Lyon’s Roman quarter, the needle moved on its own, even in silence. That was the moment the compass stopped being a scientific curiosity and became something else.

Properties

Property	Effect
Passive detection	Within 200 yards of an active harmonic source (Brotherhood rehearsal, ritual, or running Engine), the compass begins to tremble audibly.
Active site confirmation	At an active ritual site, the oscillations grow violent, confirming the cult’s location and approximate direction.
Tuning fork response	The needle oscillates toward the Command_Tuning_Fork when it is struck or resonating.

No skill roll required to use. The compass operates passively. Adrien simply has to look at it or listen to it.

Limitations: The compass detects harmonic resonance, not magic. It responds to specific sub-audible frequencies associated with the Brotherhood’s instruments and rituals. Ordinary music, street noise, and natural vibrations do not trigger it. It provides direction and rough distance (via intensity of oscillation) but not precise location.

History

Adrien constructed the compass before the campaign began, as part of his work in acoustics and geological survey. Its relevance to the Brotherhood’s operations was discovered in Lyon, where it responded to residual harmonic signatures in the Roman quarter. He has carried it since.

Appearances

Relationships

• Owned by Adrien de Montferrand — Adrien designed and built the compass for geological research. It has since become his primary tool for detecting Brotherhood activity.
• Detects Harmonic Engine — The compass needle responds to the Engine's sub-audible harmonic output.
• Resonates with Command Tuning Fork — The compass needle oscillates toward the fork when struck.