Unless you live in Berkeley, Calif., Monday, October 13, 2008, is Columbus Day, commemorating one of the most significant events in America's storied past. In 1492, Christopher Columbus, an Italian navigator in the service of Spain, led an expedition to find a shorter and safer trade route between Europe and Asia. Instead of the Indies, however, he landed somewhere in the Bahamas, putting the world on an entirely new course.

Accidental discoveries like the one we celebrate this month have shaped civilization from the dawn of recorded history. In many cases, one surprise leads to another, producing a cascade of inventions and developments that ripple and twist through time.

When Columbus returned from the New World, for example, he brought back some rubber balls that the Indians made for a game they often played. Rubber balls caught on in Europe, creating an interest in the material itself. For several centuries, inventors experimented with the peculiar substance, trying to make it tougher and more uniform. Finally, in 1839, Charles Goodyear had a mishap, overheating a mixture containing sulfur and lead. By accident, he discovered the process of vulcanization, which turns natural, springy rubber into the smooth, durable material on which most of the world relies.

It doesn't stop there, however. During World War II, chemists at General Electric began experimenting with synthetic forms of rubber, looking for a more plentiful substitute that could be harvested closer to home. One researcher tried a combination of boric acid and silicone oil, producing a non-hardening polymer that was pliable and unusually springy. The playful chemist amused others with his bouncy substance, which eventually took off as the toy we know as Silly Putty. A few years later, Apollo 8 astronauts carried Silly Putty into space, using it to fasten down tools and alleviate stress.

Another unanticipated invention from the same time period involves two brothers, Cleo and Noah McVicker, who ran a family business making wallpaper cleaner. When product demand plummeted in the early 1950s — homes were converting from coal to cleaner-burning gas and electric furnaces — Cleo's son, Joseph, began experimenting with the family's secret formula. One of his trials produced a thick, moldable substance. His sister, a kindergarten teacher, took samples of the mixture to class, letting her students use it as a substitute for clay. Cleaner and easier to shape, it was an instant hit, and in 1956, the McVicker family introduced Play-Doh to the world.

A more serious discovery, though no less an accident, occurred in a London hospital in 1928. Alexander Fleming, a brilliant Scottish biologist who kept a somewhat sloppy lab, was studying the formation and growth of staphylococci. After returning from a vacation, he found his staph cultures — prepared in haste before he left — overtaken by mold. He was about to scrap his work when he noticed that the bacteria wanted nothing to do with the contaminant. To his surprise, Fleming discovered penicillin, the world's first antibacterial agent that would be mass produced for medicinal use.

Many other landmark inventions have likewise come by accident; Teflon, Velcro, X-rays, microwave ovens, potato chips, Post-It Notes, and Polaroid photography to name a few. As designers who ply the uncharted waters of solution space, we should expect a surprise or two along the way, keeping watch for that chance discovery that could change the world, or at least our perspective on it.