In 1915, Hertha Ayrton developed a device to blow away poisonous gases from the trenches, keeping soldiers fit. More than 100,000 of the fans were used on the Western Front. Other inventions include mathematical dividers, arc lamps and electrodes, and propulsion of air. In 1893, Hertha began researching highly luminous and intensely hot discharges of electricity between two electrodes. Arc lamps were used for public lighting at the time but they would flicker and hiss on the streets. Hertha's work led to fixing this issue by binding the arc together to form one constant whole.