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benjamin franklin












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timeline: 1784
inquiring mind
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Franklin was one of the most practical inventors in history. He built many devices that were designed to help improve or solve everyday problems. Some of his inventions, like bifocal glasses, are well-known, while others are more obscure. Of the numerous inventions Franklin created, he did not patent a single one. Franklin believed that "As we benefit from the inventions of others, we should be glad to share our own...freely and gladly."

Here are a few of the useful inventions that Franklin devised or improved upon.

Swim fins: Ben Franklin loved the water. Growing up in Boston, he was drawn to the sea and often dreamed of becoming a sailor. Ben learned to swim and became an expert swimmer. Wanting to increase his speed in the water, Franklin devised fins that he wore on his hands. The fins were shaped like lily pads or an artist's paint pallet and helped the swimmer attain greater speed with each stroke.

Library chair: An avid reader, Franklin made modifications to improve and extend his library chair so that it could serve multiple purposes. He attached a fan that was operated by a foot pedal and created a reversible seat that allowed the chair to function as a seat and as a small step ladder or stepping stool.

Extension arm: Having helped found a library in Philadelphia, Franklin spent a lot of time in the stacks. To help him reach books on upper shelves that were out of his reach, he created an extension arm. The device had two "fingers" that were attached to the end of a long piece of wood or pipe. The fingers could be opened or closed by pulling on a cord that manipulated them. Similar devices are still used today.

Franklin stove: Franklin wanted to build a fireplace or small stove that would use less wood and deliver more heat. With the help of an acquaintance, Franklin modified and built a stove that he claimed would be more efficient. He marketed the stove by printing pamphlets that described the "Pennsylvania Fireplace" and its many benefits. He sold a number of the stoves, but, ironically, they didn't work very well. A later inventor modified Franklin's design to create a truly efficient model, which became known as the Franklin stove.

Lightning rod: Before Franklin's invention, lightning destroyed or damaged many buildings. Franklin's understanding of electricity allowed him to design the lightning rod, which was a metal rod attached to the high point of a building. A metal wire or cable ran from the rod, down the side of the building, and into the ground. When lighting struck, the electricity ran down the rod and cable and into the ground, preventing damage to the building. Franklin came up with the idea for the lightning rod in 1750, however it was 1753 before he perfected the invention. Franklin believed that the lightning rod was his most important invention.

Street lighting: The street lamps in Franklin's day were not very efficient and the glass globes tended to become dark with soot from the oil burned inside, requiring almost daily cleaning. Franklin determined that the problem had to do with a lack of airflow within the globe. In his Autobiography, Franklin describes an improvement he made to street lights: "I therefore suggested composing them of four flat panes, with a long funnel above to draw up the smoke, and crevices admitting air below, to facilitate the ascent of the smoke; by this means they were kept clean, and did not grow dark in a few hours, as the London lamps do, but continu'd bright till morning."

Odometer: As postmaster, Franklin was concerned with providing fast and efficient service. He wanted to measure the distance between certain points so that he might establish more efficient postal routes. For this purpose, he devised an odometer that attached to his carriage. By counting the rotations of the wheels, it calculated the distance the carriage traveled.

Three-wheel clock: Franklin invented a 24-hour, three-wheel clock that was much simpler than most clock designs of the time. Franklin's clock, like others from that period, only had one hand. Minute hands were not added to clocks until later. Franklin biographer Carl Van Doren describes this invention as "a curious clock, economical but not quite practical." In 1758, Franklin's friend, James Ferguson, improved the clock, much to Franklin's pleasure.

Bifocal glasses: Anyone who has had to switch back and forth between reading glasses and distance glasses knows why Franklin invented his "double spectacles." Franklin had his optician take the lenses from his two sets of glasses, cut the lenses in two horizontally, and then mount them back into spectacle frames, with the lens for close work at the bottom and the lens for distance at the top. Thus, bifocals were invented.

Daylight Savings Time: In 1784, while Franklin was living in France, he wrote a humorous letter to the Journal of Paris, in which he suggested that it would be more thrifty to use natural light than to burn candles or oil lamps. In his tongue-in-cheek commentary, Franklin recommended that the city of Paris enact a number of laws which would force Parisians to get up with the sun and retire early in the evening. Later, Franklin's letter was published as an essay under the title of An Economical Project. We will never know if Franklin intended anyone to take his idea seriously, but every April and October people reset their clocks to "spring ahead" or "fall back."


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