Before electronics, a musician who wanted the right pitch had to carry it. For two centuries there was no oscillator, no tuner, no electric reference tone, and so pitch travelled the only way it could: in a pocket, as a small piece of shaped metal that a player kept with them from one hall to the next. The instrument that made this possible was the tuning fork, invented in 1711 by John Shore, a trumpeter and lutenist at the English court.

It is an elegantly simple object, a small forked bar of metal that, when struck, rings at one fixed frequency. The two prongs vibrate against each other in a way that settles almost instantly on a single steady pitch, purer and more stable than a plucked string, and the sound holds long enough to tune against. What made it revolutionary was not the physics alone but the portability. A tuning fork gave musicians a reference they could trust and take anywhere, the same note in London as in a country church, unaffected by weather or the state of a nearby harpsichord.

In an age when pitch drifted from place to place and instrument to instrument, here at last was a fixed point small enough to slip into a waistcoat. That a court trumpeter should invent it is fitting. Shore lived by pitch, and he gave everyone who followed a way to hold onto it. For the two centuries between his workshop and the arrival of electronic tuning, the little ringing fork was how the world agreed, quietly and portably, on what a note should sound like.