The law makes no special mandate. In 1789, Justice James Wilson was sworn in by the mayor of Philadelphia, Pennsylvania, where the court first sat. Thurgood Marshall, the nation's first African-American justice, took the Constitutional Oath in 1967 from Associate Justice Hugo Black, an Alabaman.
ballast - A device required by electric-discharge light sources such as fluorescent or HID lamps to regulate voltage and current supplied to the lamp during start and throughout operation.
Smart-lighting emergency ballast for fluorescent lamps The function of a traditional emergency lighting system is the supply of a minimum illuminating level when a line voltage failure appears. Therefore, they have to store energy in a battery module to supply the lamps in that case of failure.