Benjamin Franklin was a prolific inventor who created many devices and civic institutions that people still rely on today. He never patented any of his inventions, believing that they should be shared freely. Here are some of his most significant inventions:

• Lightning Rod: Franklin used his understanding of electricity to develop a cheap solution to keep houses from burning down. The rod diverted electricity from a lightning strike into the ground near a building.

• Swim Fins: An avid swimmer, Franklin invented flippers—two oval-shaped pieces of wood that, when grasped by hand, provided extra propulsion in the water. He also tried flippers for his feet, but they werent as effective.

• Flexible Catheter: Franklin was inspired to invent a better catheter in 1752 when he saw what his kidney (or bladder) stone-stricken brother had to go through. Catheters at the time were simply rigid metal.

• Glass Armonica: Franklin invented the armonica in 1761, a musical instrument made of spinning glass. It was played by touching moistened fingers to the rims of the glasses as they spun.

• Bifocals: Tired of switching between glasses, Franklin invented "double spectacles" or what we now call bifocals. He cut the lenses of two pairs of glasses—one for seeing far away and one for reading—and put them together in a single frame.

• Franklin/Pennsylvania Stove: Franklin designed a stove that was more efficient than other stoves of the day. It used less fuel and produced more heat.

• 24-Hour, Three-Wheel Clock: Franklin designed a clock that was much simpler than other designs of the day. It only used three gears to keep time.

• Long Arm (Extension Arm): Franklin invented a long arm to reach high books.

• Rate Chart Used by Postmasters: Franklin designed a rate chart used by postmasters.

• Political Cartoon: Franklin created a political cartoon in America, published in The Plain Truth.

• Chart of the Gulf Stream: Franklin charted the Gulf Stream during transatlantic trips to and from London.

• Scotch Kale, Swiss Barley, Chinese Rhubarb, and Kohlrabi: Franklin introduced the colonists to these vegetables.

Franklin also discovered ways to keep streets cleaner and deal with waste management, that storms can move in an opposite direction from the direction of the wind, and that prolonged exposure to lead would cause sickness. He was the first to use the words "positive" and "negative" to...