The Inventions of Benjamin Franklin

Benjamin Franklin was one of our nation’s founding fathers and one of its most ingenious inventors.

By Dr. Eric S. Hintz
Historian of Science
Lemelson Center for the Study of Invention and Innovation
Smithsonian Institution

During the election week back in November, my sons Patrick (age 9, 3rd grade) and Gavin (age 8, 2nd grade) had a few extra vacation days as our school district closed several local schools to use them as polling places.  In the spirit of the election, my wife Emma and I took a few vacation days ourselves and planned a civically-minded family trip to Philadelphia. Like many visitors to Philadelphia, we toured the Liberty Bell, Independence Hall, the National Constitution Center, flag maker Betsy Ross’s house, and the U.S. Mint. We also toured the National Park Service’s Benjamin Franklin Museum to learn more about Philadelphia’s most famous resident and most ingenious inventor. What follows is not a thoroughly researched and comprehensive review of Franklin’s inventive career, but more humbly, a dad’s photo album and description of cool things he learned during a family trip.

The large white steel frame in the foreground marks the location and size of Benjamin Franklin’s Philadelphia home in Franklin Court. Franklin’s grandchildren demolished the house in 1812, but the foundations are still visible through viewing portals. The Benjamin Franklin Museum (background, right) interprets Franklin’s extraordinary life and displays many of his inventions. NPS photo by Joseph Kitchen.

Benjamin Franklin (1706-1790) was one of the founding fathers of the United States and a man of many talents.  Though born in Boston, he moved to Philadelphia as a teenager in 1723 and subsequently established himself as a printer, publisher, postmaster, civic activist, author, political theorist, statesman, and diplomat. Franklin helped found many of Philadelphia’s core civic institutions, including The Library Company, a subscription based lending library; the Union Fire Company, Philadelphia’s first volunteer fire brigade; Pennsylvania Hospital, America’s first public hospital; and the University of Pennsylvania, the colonies’ first non-sectarian college.  At age 70, Franklin helped Thomas Jefferson draft the Declaration of Independence and at age 81, he helped frame the United States Constitution.

Franklin was first and foremost a printer.  He proposed his own epitaph long before he died: “The Body of BENJAMIN FRANKLIN, Printer. Like the Covering of an old Book, Its contents torn out and stript of its Lettering and Gilding, Lies here, Food for Worms. But the Work shall not be lost, It will (as he believ’d) appear once more In a new and more beautiful Edition Corrected and amended By the Author.” My family enjoyed seeing the National Park Service’s interpretive staff operate a replica of Franklin’s printing press in the very Market Street offices where he once practiced his trade.

My family—(left to right) Emma, Gavin, and Patrick Hintz—enjoy the National Park Service’s printing demonstration on a replica of the Franklin printing press, 7 November 2016, photo by the author.

Franklin was also a talented “natural philosopher” and inventor, and in 1743 he organized the American Philosophical Society, America’s first and oldest scholarly society.  As a scientist, he was a major figure in the American Enlightenment, well-known for his discoveries and theories regarding electricity. For example, Franklin introduced several new (and now common) words into our electrical vocabulary, including “battery,” “positive” and “negative,” “conductor,” and “discharge.” Franklin was also a prolific inventor, and his friends often marveled at the many whimsical “curiosities” they found at his Philadelphia home. The Benjamin Franklin Museum could not possibly display all of its namesake’s inventions in its limited exhibition space; for example, I did not see Franklin’s lightning rod or eponymous “Franklin” cook stove on display.  Nevertheless, I was delighted to learn more about Franklin’s many other contributions to 18th-century technology.

Like all kids, the young Benjamin Franklin tried to invent new ways to have more fun. He fashioned some swim paddles to help him swim faster!  “When I was a boy,” Franklin later wrote to a friend, “I made two oval palettes. . . . They much resembled a painter’s palette. . . . I also fitted to the soles of my feet a kind of sandals.”  He swam faster, but ultimately found the paddles difficult to use.

A reproduction of swim paddles described in the writings of Benjamin Franklin, on display at the Benjamin Franklin Museum, photo by the author.

Franklin invented bifocal eyeglasses by cutting the lenses of two pairs of spectacles and preserving “half of each kind associated in the same Circle.” This allowed Franklin to move his “Eyes up or down, as I want to see distinctly far or near.”

Bifocals, about 1790, based on Franklin’s original design. From the collection of David Fleishman, MD, curator of, and on display at the Benjamin Franklin Museum, photo by the author.

Franklin served as Philadelphia’s postmaster for many years and was later promoted to deputy postmaster-general for all of Britain’s American colonies in 1753. After the Revolution, Franklin became the first US Postmaster General. While traveling to inspect post offices from New Jersey to New England, Franklin used an odometer to measure the distance between postal stations. The odometer on display in the museum, which had registered 1,600 miles, was attached to the wheel of Franklin’s carriage.

An odometer, possibly designed by Franklin, about 1763, and installed on his carriage. From the Frankliniana Collection, The Franklin Institute of Philadelphia, and on display at the Benjamin Franklin Museum, photo by the author.

In his Autobiography, Franklin describes a plan for improving his character, listing “temperance” as the first of thirteen key virtues he hoped to cultivate. However, Franklin struggled with this particular virtue, and in fact, suffered from obesity and gout in his later years. Franklin loved a good meal, so it was not surprising to see that he had invented an ingenious “divided soup bowl” to prevent spills when eating aboard ship. Franklin proposed “soup dishes in divisions, like a set of small bowls united together” around a main bowl. Then “when the ship should make a sudden heel, the soup would not in a body flow over one side, but would be retained in the separate divisions.”

A reproduction of Franklin’s divided soup bowl, on display at the Benjamin Franklin Museum, photo by the author.

In my opinion, Franklin’s most fascinating invention was a musical instrument known as the glass armonica. Franklin invented the armonica in 1761; the concept is based on the sound produced by running a wet finger around the rims of water-filled drinking glasses to produce different pitches. Working with glassblower Charles James in London, Franklin made a few dozen glass bowls, tuned to notes by their varying size and nested one inside the next with cork. Each bowl was made with the correct size and thickness to give the desired pitch without requiring any water. An iron rod ran horizontally through the nested glass bowls so they were turned on their sides facing the player. A foot pedal rotated the rod so that all the interconnected bowls spun together, allowing the musician to play multiple notes at once, much like a piano.

Reproduction of a glass armonica, 1761-1762, as displayed in the Benjamin Franklin Musuem, based on the original in the Frankliniana Collection at the Franklin Institute of Philadelphia. Photo by the author.

Moistened fingers touched to the edge of the spinning glasses produced an ethereal, haunting sound, which Franklin’s wife Deborah described as “the musick of angels.” Franklin himself noted that “of all my inventions, the glass armonica has given me the greatest personal satisfaction.”

In this video, posted by the Toronto Star on 9 April 2013, composer William Zeitler demonstrates a modern version of the glass armonica, first invented by Benjamin Franklin in 1761.

Franklin produced many ingenious inventions over the course of his life, but never secured any patents. Franklin believed that “as we enjoy great Advantages from the Inventions of others, we should be glad of an Opportunity to serve others by any Inventions of ours, and this we should do freely and generously.” We should be grateful that Franklin freely shared his extraordinary talents—for invention, and in so many other domains. After learning more about the man, it is easy to agree with historian Walter Isaacson, who called Franklin “the most accomplished American of his age and the most influential in inventing the type of society America would become.”


Originally published by Smithsonian Institution, 12.16.2016, reprinted with permission for educational, non-commercial purposes.



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