Did you Know:
Benjamin Franklin is the only founding father to have signed all four of the key documents establishing the U.S; the Declaration of Independence (1776), the Treaty of Alliance with France (1778), the Treaty of Paris establishing peace with Great Britain (1783) and the U.S. Constitution (1787).
Scientist & Inventor
In 1748, at the age of 42, Franklin had expanded his printing business throughout the colonies and became successful enough to stop working. Retirement allowed him to concentrate on public service and also pursue more fully in his longtime interest in science. In the 1740s, he conducted experiments that contributed to the understanding of electricity and invented the lightning rod, which protected buildings from fires caused by lightning. In 1752, he conducted his famous kite experiment and demonstrated that lightning is electricity. Franklin also came up with a number of electricity-related terms, including battery, charge, and conductor.
In addition to electricity, Franklin studied a number of other topics, including ocean currents, meteorology, causes of the common cold and refrigeration. He developed the Franklin stove, which provided more heat while using less fuel than other stoves, and bifocal eyeglasses, which allow for distance and reading use. In the early 1760s, Franklin invented a musical instrument called the glass armonica. Composers such as Ludwig Beethoven (1770-1827) and Wolfgang Mozart (1756-91) wrote music for Franklin’s armonica; however, by the early part of the 19th century, the once-popular instrument had largely fallen out of use.
Top left to bottom right: Benjamin Franklin, George Washington, John Adams, Thomas Jefferson, Samuel Adams, James Monroe, Alexander Hamilton, John Marshall, Patrick Henry, George Mason and James Madison
This Old Map
The Gulf Stream was named and mapped by Franklin and Folger. It is a warm, strong ocean current that pushes northeast from the Gulf of Mexico, up the Atlantic coast, towards Europe.
This map was first commissioned in London by Franklin, using coordinates provided by his cousin on his mother’s side, Timothy Folger, a merchant seaman from Nantucket. Franklin first published a report for seamen in 1769. He tested the theory during three ocean crossings: traveling home in 1775, traveling to France in 1776, and home again in 1785. With his grandson, William Temple Franklin, he lowered a thermometer into the ocean three or four times a day, recording each temperature.
This prompted Franklin to inquire about something that had been peeving him.
Why did it take British mail packet ships so much longer to reach America than it took regular merchant ships?
It hit Folger that the British mail captains must not know about the Gulf Stream, with which he had become well-acquainted in his earlier years as a Nantucket whaler. Franklin later quoted his cousin’s explanation like this:
We are well acquainted with that stream, says he, because, in our pursuit of whales, which keep near the sides of it, but are not to be met with in it, we run down along the sides, and frequently cross it to change our side: and in crossing it have sometimes met and spoke with those packets, who were in the middle of it, and stemming it. We have informed them that stemming a current, that was against them to the value of three miles an hour, and advised them to cross it and get out of it; but they were too wise to be counseled by simple American fishermen.
In other words, westbound British packet ships were losing precious time by sailing into and against the warm, strong current. Folger sketched out the rough location for Franklin, who soon made prints, along with his cousin’s directions for how to avoid what he dubbed the “Gulph Stream.”
Is it Accurate?
Compare Franklin and Folger’s 18th-century chart to modern computer-generated models of the Gulf Stream, and they match up remarkably well.
While Franklin himself made observations of the stream on ocean voyages, the accuracy of the chart is really due to Folger and his inherited whaling knowledge. Also, Spanish mariners had known about the Gulf Stream since the 1500’s, but Franklin was the one with the good instincts to map it, and that, combined with his fame, has landed him with most of the credit.
Kite & Lightning Rod Experiment
What would you think if you saw a man chasing a thunder and lightning storm on horseback? You would probably wonder what on Earth he was trying to do. Well, if you lived in the 1700s and knew Benjamin Franklin, this is just what you might see during a terrible storm. Ben was fascinated by storms; he loved to study them. If he were alive today, we could probably add “storm-chaser” to his long list of titles.
In 1746, Franklin first stumbled upon other scientists’ electrical experiments. He quickly turned his home into a little laboratory, using machines made out of items he found around the house. During one experiment, Ben accidentally shocked himself. In one of his letters, he described the shock as
“…a universal blow throughout my whole body from head to foot, which seemed within as well as without; after which the first thing I took notice of was a violent quick shaking of my body…” (He also had a feeling of numbness in his arms and the back of his neck that gradually wore off.)
Franklin spent the summer of 1747 conducting a series of groundbreaking experiments with electricity. He wrote down all of his results and ideas for future experiments in letters to Peter Collinson, a fellow scientist and friend in London who was interested in publishing his work. By July, Ben used the terms positive and negative (plus and minus) to describe electricity, instead of the previously used words “vitreous” and “resinous.” Franklin described the concept of an electrical battery in a letter to Collinson in the spring of 1749, but he wasn’t sure how it could be useful. Later the same year, he explained what he believed were similarities between electricity and lightning, such as the color of the light, its crooked direction, crackling noise, and other things. There were other scientists who believed that lightning was electricity, but Franklin was determined to find a method of proving it.
By 1750, in addition to wanting to prove that lightning was electricity, Franklin began to think about protecting people, buildings, and other structures from lightning. This grew into his idea for the lightning rod. Franklin described an iron rod about 8 or 10 feet long that was sharpened to a point at the end. He wrote, “the electrical fire would, I think, be drawn out of a cloud silently before it could come near enough to strike…” Two years later, Franklin decided to try his own lightning experiment. Surprisingly, he never wrote letters about the legendary kite experiment; someone else wrote the only account 15 years after it took place.
In June of 1752, Franklin was in Philadelphia, waiting for the steeple on top of Christ Church to be completed for his experiment (the steeple would act as the “lightning rod”). He grew impatient and decided that a kite would be able to get close to the storm clouds just as well. Ben needed to figure out what he would use to attract an electrical charge; he decided on a metal key and attached it to the kite. Then he tied the kite string to an insulating silk ribbon for the knuckles of his hand. Even though this was a very dangerous experiment, (you can see what our lightning rod at the top of the page looks like after getting struck), some people believe that Ben wasn’t injured because he didn’t conduct his test during the worst part of the storm. At the first sign of the key receiving an electrical charge from the air, Franklin knew that lightning was a form of electricity. His 21-year-old son William was the only witness to the event.
Two years before the kite and key experiment, Ben had observed that a sharp iron needle would conduct electricity away from a charged metal sphere. He first theorized that lightning might be preventable by using an elevated iron rod connected to earth to empty static from a cloud. Franklin articulated these thoughts as he pondered the usefulness of a lightning rod:
“May not the knowledge of this power of points be of use to mankind, in preserving houses, churches, ships, etc., from the stroke of lightning, by directing us to fix, on the highest parts of those edifices, upright rods of iron made sharp as a needle…Would not these pointed rods probably draw the electrical fire silently out of a cloud before it came nigh enough to strike, and thereby secure us from that most sudden and terrible mischief!”
Franklin began to advocate lightning rods that had sharp points. His English colleagues favored blunt-tipped lightning rods, reasoning that sharp ones attracted lightning and increased the risk of strikes; they thought blunt rods were less likely to be struck. King George III had his palace equipped with a blunt lightning rod. When it came time to equip the colonies’ buildings with lightning rods, the decision became a political statement. The favored pointed lightning rod expressed support for Franklin’s theories of protecting public buildings and the rejection of theories supported by the King. The English thought this was just another way for the flourishing colonies to be disobedient to them.
Franklin’s lightning rods could soon be found protecting many buildings and homes. The lightning rod constructed on the dome of the State House in Maryland was the largest “Franklin” lightning rod ever attached to a public or private building in Ben’s lifetime. It was built in accord with his recommendations and has had only one recorded instance of lightning damage. The pointed lightning rod placed on the State House and other buildings became a symbol of the ingenuity and independence of a young, thriving nation, as well as the intellect and inventiveness of Benjamin Franklin.
Note: The text is © The Franklin Institute. All rights are reserved.
More Famous Inventions
The battery contains 35 jars (seven rows of five). Each jar is covered with foil to a height of 9 inches and has a wooden cap from which contact wires project within.
The Leyden jar was developed in 1745-47 by scientist Pieter van Musschenbroeck of the University of Leyden (today Leiden) in the Netherlands. A Leyden jar builds and stores electricity. The parts of a Leyden jar are:
1.) A cylinder made of an insulating material like glass or plastic, lined inside and out with metal foil.
2.) Water or other conducting material within the jar
3.) A metal rod or wire that passes through the cork that seals the bottle. When an electrical charge is given to the jar, the charge passes along the rod and is held within the insulated vessel until the energy is released by the touching of a conducting element to the ends of the rods or wires closing the circuit.
Franklin first used a battery of jars in 1747 and is considered to be the originator of this method of increasing the electrical charge that could be produced by a Leyden jar.
Water Harmonica & Glass Armonica
The armonica consists of 28 hemispherical glass cups, each with an open neck or socket at its center. Each neck is fitted with a cork that has an opening through which an iron rod or axle can be passed. The bowls are arranged in order of descending size and thickness, along the iron rod. The rod is mounted horizontally within a frame, above a shallow tined iron tray or pan into which water can be poured. By dipping their hands into the water and rubbing them on the rims of the cups, a musician produces musical tones.
Franklin employed an odometer to measure distances while he was developing the postal system in the Colonies. He used it to measure the roads between Philadelphia and Boston. Additionally, in the summer of 1763, Franklin completed a five-month carriage tour to inspect post offices. On that tour, he also utilized an odometer. The Institute News describing the action of an odometer (June-July 1949) noted: “When actuated from a carriage wheel having a circumference of thirteen and one-fifth feet, a mile was registered in each four hundred revolutions. If wired to the top of the front axle at the right-hand side it was easily set in operation by a nub-type projection on a hub or spoke and the dials were readily visible to both driver and rider.”