What Did Benjamin Franklin Invent? Much More Than Bifocals

By: John Fuller  | 
Macro photo of Ben Franklin on the One Hundred Dollar Bill
Benjamin Franklin's inventions were so numerous and so influential, they landed him on the $100 bill. GeorgePeters / Getty Images

Between running a print shop, engineering the U.S. postal system, starting America's first lending library and helping sow the seeds of the American Revolution, Ben Franklin also found time to draw up a vast collection of new devices. To this day, the Franklin Institute in Philadelphia, Pennsylvania, stands as an inspiration to curious minds and a tribute to clever innovations.

Franklin saw his inventions as gifts to the public and never patented a single one. "As we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours; and this we should do freely and generously," he wrote in his autobiography. So, what did Benjamin Franklin invent?


Franklin's inventions are all models of practicality. It's one thing for a team of engineers to design the Segway, but quite another for an elderly, 18th-century man to think of throwing a set of stairs on a library chair. Most of the items in this list likely had fellow colonists slapping their foreheads and exclaiming, "Why didn't I think of that?"

10. Urinary Catheter

Getty Images/Photodisc/Don Farrall

It might not be the most impressive device on Franklin's resume, but his modification of the urinary catheter was no doubt a welcome relief for hundreds of Americans with bladder problems.

Then, as now, a catheter was a thin tube inserted into a patient's urethra in order to drain urine from the bladder. But at the time, catheters were nothing more than rigid (and painful) metal tubes. Franklin's older brother John suffered from kidney stones and needed to undergo an excruciating daily ritual of jamming a bulky metal catheter into his nether regions.


To make these daily attacks on his brother's loins less painful, Franklin ran to his local silversmith with plans for a flexible catheter. "It is as flexible as would be expected in a thing of the kind, and I imagine will readily comply with the turns of the passage," he wrote to John.

9. American Celebrity

In the mid-18th century, many Europeans regarded the colonies as little more than a dangerous frontier — a rough-around-the-edges collection of trading posts where they bought their fur and cotton. Many of the world's most well-known musicians, artists and scientists were headquartered in European capitals.

As a witty Renaissance man who could also chop wood, Franklin slipped easily into their ranks, quickly gaining renown as a superstar from a relatively unknown land. He was to 18th-century North America as Björk is to modern Iceland.


When Franklin came to France as the United States' first ambassador, Parisians snapped up all manner of Franklin kitsch. His image was plastered on snuff boxes and medallions, and engravings of the man adorned the walls of any stylish French apartment. After Franklin died, the first published edition of his autobiography would be a French translation.

Like all good American celebrities, Franklin also had a charitable cause. In the years before his death, Franklin freed his two slaves, George and King, and became a vocal abolitionist.

"Slavery is such an atrocious debasement of human nature, that its very extirpation, if not performed with solicitous care, may sometimes open a source of serious evils," he wrote in 1789 [source: Franklin].

21st Century Franklins

More than 200 years after his death, Ben Franklin impersonators abound in all 50 states. For a fee, they'll show up to your event dressed in period clothing, speaking in 18th-century English, and spouting witty Franklin-isms like "a penny saved is a penny earned."

8. Swim Fins

Getty Images/Taxi/Thomas Barwick

Although Franklin was a bit soft around the middle in his later years, in his youth he was a strapping, broad-shouldered specimen of a man. Well, at least that's what he claims in his autobiography.

Either way, Franklin credited his physique to being a vigorous swimmer. When he was posted to London in the 1750s, he was known to take daily dips in the Thames.


When he was an 11-year-old in Boston, Franklin's first invention was a pair of oval planks with holes through their centers. Grasping the two planks with his hands, Franklin used the "fins" to give him a bit of extra thrust underwater.

The fins did allow the young Franklin to swim faster, but he soon ditched them after he noted that "they fatigued the wrists." He also strapped boards to his feet like sandals, but gave them up as well after finding them awkward and clunky.

In his later years, Franklin would leave his inventions for dry land, preferring to splash around without so much as a swimsuit.

In the days before heated pools and shark nets, swimming in colonial America was largely the domain of shipwrecked sailors and skinny-dipping children. Franklin's early advocacy for the sport has since earned him recognition in the International Swimming Hall of Fame and the United States Swim Schools Association Hall of Fame.

7. The Odometer

Mail was a haphazard affair in colonial America. Letters between cities were carried by whoever was available, and post offices were little more than sacks of mail stashed in the back room of your local tavern. Many colonists would make up to five copies of a letter and send them in five different directions just to make sure one of them made it to its destination [source: PBS].

In the 1760s, the British government tapped Franklin to make some sense of the colonies' slapdash postal system. A man of letters himself, Franklin dove into the task with a firm resolve to speed up communication between the colonies.


He started by touring America's major postal centers, studying ways to standardize and streamline mail delivery. Along the way, Franklin charted the distances between postal stations by attaching a geared device to the rear wheel of his horse carriage. Every 400 revolutions made by his carriage wheel would cause the device to click ahead one mile (1.6 kilometers).

By the end of Franklin's tour, he had gathered a stunningly accurate survey of early colonial roads.

It wasn't the world's first odometer; rudimentary mileage recorders had been appearing as far back as ancient Roman times. Franklin's design also wasn't the last odometer; inventors in Nova Scotia and the Midwest would independently conceive of similar devices in decades to come. However, none would put the odometer to such practical use as Franklin.

Most modern automobile odometers are electronic, but you can still see a slightly worn version of Franklin's odometer at the Benjamin Franklin Museum in Philadelphia [source: Benjamin Franklin Tercentenary].

Lofty Words

While living in Paris as France's first US ambassador, Franklin witnessed a demonstration of another new transportation innovation: the hot air balloon. "What use is it?" said one observer to Franklin. "What use is a newborn baby?" he replied [source: Lemay].

6. American Political Cartooning

Getty Images/Archive Photos/MPI

In 1752, the American colonies stood on the brink of war with France. As English-speaking settlers moved inland, they were constantly bumping against French territory. (In the mid-18th century, France laid claim to a portion of the American interior stretching from New Orleans, up through the American Midwest into what is now Eastern Canada.)

Franklin owned the Pennsylvania Gazette at the time and believed that a defensive union of the colonies was essential to protect against possible French attacks.


In a published drawing entitled "Join, or die," Franklin depicted a snake cut into eight pieces: One piece for each of the colonies. The engraving referenced a popular superstition at the time that if the pieces of a decapitated snake were arranged together before sunset, the snake would come back to life.

It's no Doonesbury, but "Join, or die" is widely believed to be America's first political cartoon. The simple drawing was reproduced throughout the American colonies and even staged a comeback during the American Revolution.

Meanwhile, other publishers took Franklin's lead and began using graphics and snippets of text to communicate their own political ideals. Franklin had unwittingly kicked off a new American art form, and today, more than 300 editorial cartoons are published daily in American newspapers.

5. Glass Armonica

While living in England as a Pennsylvanian diplomat in the 1750s, Franklin stopped by Cambridge University to take in a concert by Edmund Delaval, a professional wine glass player. Delaval arranged a collection of wine glasses on a table, "tuned" them by filling each with a different quantity of water and then played them by carefully rubbing their rims in succession.

As the audience soaked up the smooth, ethereal sound of the glasses, Franklin couldn't help but notice room for improvement.


Playing wine glasses is woefully time-consuming to set up — and hard on the wrists to play. Franklin wracked his brain to figure out he could create music from glass without needing to empty out his kitchen cupboards.

Two years of experimentation later, Franklin debuted his glass armonica, a collection of different-sized glass bowls arranged on a rotating shaft. By spinning the shaft with a foot pedal and running wetted fingers over the rotating bowls, Franklin found he could coax out chords and melodies that Delaval could only dream of.

The new instrument was soon making the rounds of parlors and concert halls across Europe and America. Mozart and Beethoven penned music for the new instrument, and Franz Mesmer, a pioneer in hypnosis, used the instrument to guide his patients into deeper trances.

In the 19th century, however, the popularity of the instrument died out as a rumor spread that the ghostly sounds it produced could provoke insanity in the listener.

Ben's Favorite

"Of all my inventions, the glass armonica has given me the greatest personal satisfaction," reads an oft-quoted Franklin passage [source: Fox].

4. Reaching Device (the Long Arm)

Getty Images/The Image Bank/Derek E. Rothchild

At 5 feet, 11 inches (180 cm), Franklin was actually on the tall side for a Founding Father: Not a guy you would expect to invent a reaching device. But Franklin liked his books — even going so far as to become a vegetarian at 16 so he could save more money for books — and by late adulthood, Franklin's homes were jammed with floor-to-ceiling bookshelves.

To reach the top shelves without using a step ladder, Franklin fashioned a "long arm" in his workshop. It was simply a piece of wood with two "fingers" mounted on the end. By pulling on a cable, Franklin could bring the fingers together to grip a book off a high shelf.


Although they're rarely seen in libraries, versions of the long arm remain popular among anybody needing a bit of extra reaching power. People with dwarfism (adults who are under 4 feet, 10 inches, or 147 cm tall) will sometimes carry reaching arms to grasp door handles and countertops.

Highway cleanup crews carry stainless steel arms to pick up litter on the side of the highway, and people suffering from severe arthritis will use reaching devices to take the strain off their joints.

3. The Franklin Stove

In Franklin's day, colonists staved off the chilly Pennsylvania winters by stocking their roaring fireplaces with oak, hickory and maple logs carried in from the surrounding countryside. Only a few decades after the city's founding, however, the forests around Philadelphia were growing thin, forcing Philadelphians to travel as much as 100 miles to find fuel — not an easy task on a horse and buggy.

Franklin resolved to combat the growing energy crisis by finding a more efficient way to heat colonial homes.


Fireplaces are woefully inefficient: They consume fuel uncontrollably, and most of the heat shoots up the chimney. Franklin solved these problems by enclosing the fire in a cast-iron box positioned in the center of the room. The stove radiated heat from all four sides, and users could control the rate at which wood burned by adjusting the stove's airflow.

Safely enclosed, the stove also eliminated the risk of fires being ignited by stray sparks. Versions of Franklin's original design are now a staple of cabins and cottages around the world.

Wake Up, Paris!

Franklin's love of energy conservation prompted him in 1784 to pen a satirical letter to the Journal of France. Poking fun at the French tendency to stay out late and sleep in the next day, Franklin suggested moving the clocks backward to take advantage of daylight hours.

"Every morning, as soon as the sun rises, let all the bells in every church be set ringing; and if that is not sufficient, let cannon be fired in every street, to wake the sluggards effectually," he wrote. The letter was obviously a joke, but many people still credit Franklin with conceiving daylight saving time.

2. Bifocal Eyeglasses

Getty Images/Workbook Stock/Sara Remington

As he reached old age, Ben Franklin found himself becoming both near- and farsighted. Outdoors, he needed a set of long-distance lenses to see where he was going, but when he examined something close-up, he would need to swap out his outdoor glasses for a pair with different lenses.

It quickly became a frustrating ritual, so Franklin simply cut the two glasses in half and joined them together in one frame.


With the new glasses, Franklin could see long distances by peering through the lens at the top of the glasses. To read, he would simply peer through the bottom of the lens. Amazingly, both farsighted and nearsighted glasses had been around for centuries before Franklin's birth, but nobody had thought to join them together.

Aside from a few improvements, Franklin's original bifocal design has remained relatively unchanged until modern times. In 2006, however, a team of Arizona researchers announced they had designed eyeglasses with lenses that could switch from far-sighted to near-sighted with the push of a button [source: National Academy of Sciences].

1. The Lightning Rod

Lightning was a supernatural scourge to the wooden cities of the 18th century. Churches were particularly susceptible, since they were often the tallest structures around, and a single electrical storm was known to lay waste to buildings across entire regions.

In Franklin's lifetime, a bolt of lightning even killed 3,000 people in Italy after it struck a church basement packed with gunpowder. Aside from fervent praying, no one knew how to protect buildings from this "electrical fire."

Franklin retired from the publishing business at 42 to work full-time on electrical experiments. After countless hours spent tinkering with static electricity, Franklin figured that if a metal rod could be fixed to the top of a building and wired to the ground with a cable, it could gently extract the "fire" from a cloud before it had a chance to do any damage.

Franklin sent news of his protective rod across the Atlantic, where it was first adopted in the churches and cathedrals of the French countryside.


Franklin coined many of the words still used in modern electronics, including "battery," "charge," "positive" and "negative."


  • Fox, Catherine Clark. "Second Time Around." Smithsonian.com. Feb. 1, 2007. (Jan. 21, 2011) http://www.smithsonianmag.com/arts-culture/armonica.html
  • Franklin, Ben. "An Address to the Public from the Pennsylvania Society for Promoting the Abolition of Slavery, and the Relief of Free Negroes Unlawfully Held in Bondage." Nov. 9, 1789. (Jan. 21, 2011) http://memory.loc.gov/cgi-bin/query/r?ammem/rbpe:@field(DOCID+@lit(rbpe14701000))
  • BBC.com. "Join, or Die' -- the Political Cartoon by Benjamin Franklin." July 24, 2003. (Jan. 21, 2011) http://www.bbc.co.uk/dna/h2g2/A1091369
  • Benjamin Franklin House. "Group visits." (Jan. 21, 2011)http://www.benjaminfranklinhouse.org/site/sections/visit/group-visits.html
  • Benjamin Franklin Tercentenary. "Library chair with folding steps, 1760-1780." (Jan. 21, 2011)http://www.benfranklin300.org/frankliniana/result.php?id=51&sec=1
  • Benjamin Franklin Tercentenary. "Odometer, ca. 1763." (Jan. 21, 2011) http://www.benfranklin300.org/frankliniana/result.php?id=170&sec=1
  • Bowman, Jake. "Ben Franklin, P2P Pioneer." Wired.com. April 2002. (Jan. 21, 2011) http://www.wired.com/wired/archive/10.04/rants.html
  • Conradt, Stacy. "History of the U.S.: A Ridiculously Long and Incomplete List of Things Ben Franklin Invented." MentalFloss.com. Sept.28, 2010. (Jan. 21, 2011)http://www.mentalfloss.com/blogs/archives/68599
  • Franklin, Benjamin. "An Economical Project." 1784. (Jan. 21, 2011) http://www.webexhibits.org/daylightsaving/franklin3.html
  • Golden, Frederic. "When Sparks Flew." Time.com. June 29, 2003. (Jan. 21, 2011).http://www.time.com/time/2003/franklin/bfkite.html
  • Independence Hall Association. "Benjamin Franklin Timeline." (Jan. 24, 2011) http://www.ushistory.org/franklin/info/timeline.htm
  • Lemay, J.A. Leo. "Ben Franklin -- facts and fallacies." University of Delaware. (Jan. 21, 2011) http://www.udel.edu/PR/UDaily/2005/mar/franklin061605.html
  • Lemelson-MIT Program. "The Franklin Stove." (Jan. 21, 2011)http://web.mit.edu/invent/iow/franklin.html
  • Lemisch, L. Jesse. "Benjamin Franklin: The Autobiography and Other Writings." Penguin, 1961.
  • National Academy of Sciences. "Switchable electro-optic diffractive lens with high efficiency for ophthalmic applications." April 5, 2006. (Jan. 21, 2011) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1458838/?tool=pmcentrez
  • PBS. "Celebrity." (Jan. 21, 2011) http://www.pbs.org/benfranklin/l3_world_celebrity.html
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Ben Franklin Inventions FAQ

What did Benjamin Franklin invent?
Benjamin Franklin invented a number of things, including the odometer, glass armonica, the long arm and bifocal eyeglasses.
What is Benjamin Franklin most famous for?
Apart from his inventions, Benjamin Franklin was one of the Founding Fathers of the United States and helped draft the Declaration of Independence in 1776.
How did Benjamin Franklin discover electricity?
In 1752, Ben Franklin conducted his famous lightning rod experiment in which he showed that lightning was electricity. He attached a key to the line of a kite and flew the kite during a thunderstorm. When the lightning hit the key, it caused it to spark.
Why was the lightning rod so important?
Franklin's electrical experiments discovered that a sharp rather than a smooth point was more capable of discharging quietly and at a far greater distance. The lightning rod experiment showed that electricity could pass harmlessly through the path of least resistance through the rod and its cables. Lightning rods are still used to protect buildings from lightning strikes.
What was Ben Franklin's most famous invention?
Ben Franklin had quite a few famous inventions that are considered to be historically significant. These include the Franklin stove, bifocals and the lightning rod.