In the scientific world, Nikola Tesla is remembered principally for his work on the rotating magnetic field, which made possible the alternating-current generators that supply most of the world with electricity today. In honour of this achievement a scientific unit was named after him. The 'tesla' does not often crop up in layman's conversation, however, as it is used to calculate the force of a magnetic field. His name is also immortalised in the Tesla coil, a device that allows a transformer to generate high frequency current at a very high voltage. It is still used in televisions, radios and other modern electronic devices. He invented the coil in the course of his work on alternating current in 1891.
In later years Tesla was something of a solitary eccentric, often to be seen walking to the New York Public Library from his hotel, where his room had to serve as his laboratory. Although he developed a phobia for germs, it appears he did not suspect the city's pigeons of being carriers of disease; watching pleasures in life.
Occasionally Tesla would emerge from his hotel-room with announcements of discoveries and inventions that people found increasingly hard to take seriously. In 1934, for example, he told the press that he had devised a deathray. This was to be the ultimate deterrent that would put an end to war. It consisted of a beam of high-velocity particles that would destroy squadrons of enemy aircraft at a range of 400 km (250 miles). The details of this weapon were never disclosed.