After experimenting between 1800 and 1802 with brief contact sparks using the newly invented voltaic pile, Humphry Davy formally demonstrates a continuous, stable electrical discharge between two physically separated carbon rods, ionizing the intervening air, in his Bakerian Lecture before the Royal Society (November 1806) and in laboratory demonstrations at the Royal Institution in 1807. In 1808-1810 he builds a battery of 2,000 plate pairs and demonstrates the arc at large scale publicly, coining the term 'arc' for the curved shape the luminous plasma takes. This is the physical basis on which arc radio-frequency generators (Duddell, Poulsen) would be built a century later.