Sun-spot disturbances of terrestrial magnetism

For many years magnetic storms at irregular intervals have been known to interfere seriously with the operation of electrical communication systems. The storm of March 24, 1940, however, considered to be possibly the greatest magnetic storm that has ever been recorded, not only interfered widely with communication systems, but also caused numerous interruptions in electric-power systems. The latter experiences are reviewed here, followed by some notes on current theories concerning magnetic storms.