An instrument is a concrete or abstract tool intended for a purpose other than mechanical work, in particular a refined one.
Musical instruments are devices designed to produce music, frequently by plucking or striking a string or bell or drum surface, or by forcing air to resonate (see wind instruments).
... tube station[?]
Mark Lane tube station[?]
Marlborough Road tube station[?]
North End tube station[?] (aka Bull & Bush; never opened)
North Weald tube station[?] ...