In the 1890s, grape growers in Europe erected thousands of so-called hail cannons near their vineyards. The mouths of the guns were fitted with sheet-iron funnels; farmers loaded them with gunpowder (but no projectiles) and fired into an approaching storm. Theory held that excess cloud moisture condensed around the smoke particles, forming rain instead of crop-damaging hail. But after devastating hailstorms in 1902 and 1903, most hail cannons were dismantled, and scientists pronounced them worthless. Some ideas, though, refuse to die. Today hail-averse folks hurl sound waves at storms with acetylene-fired cannons, hoping the noise will prevent hail. Says Roelof Bruintjes of the National Center for Atmospheric Research: "There is no scientific basis to it."