In 1907 the Italian Royal Academy of Sciences noted that tests of anti-hail cannons weren’t effective and were expensive and useless. By the early twentieth century, anti-hail cannons disappeared. Replacing the cannons were anti-hail rockets that would explode 800 grams of dynamite, above the ground, to prevent hail formation. These explosions caused cold core eddies that surround hail, pulverizing it. These rockets were in conflict with safety measures implemented by civil aviation. In 1972, the Corballan Company of France marketed a new version of the hail cannon and remains the largest manufacturer of the devices. The new cannons substitute acetylene for black powder, automatically load and reload and are fired from remote locations.