Electric light by the first practical electric arc light in 1806. By the 1870s, Davy's arc lamp had been successfully commercialized, and was used to light many public spaces. The development of a steadily glowing filament suitable for interior lighting took longer, but by the early twentieth century inventors had successfully developed options, replacing the arc light with incandescents. The energy efficiency of electric lighting has increased radically since the first demonstration of arc lamps and the incandescent light bulb of the 19th century. Modern electric light sources come in a profusion of types and sizes adapted to many applications. Most modern
Royal Society and acting as trustees for the society's possessions and estates. Members are elected annually via a postal ballot, and current standing orders mean that at least ten seats must change hands each year. The council may establish (and is assisted by) a variety of committees, which can include not only fellows but also outside scientists. Under the charter, the president, two secretaries and the treasurer are collectively the officers of the society. The current officers are: The President of the Royal Society is head of both the society and the council. The details for the presidency were set out in