Benjamin Franklin's ideas, inventions, and improvements
On this page, many of Benjamin Franklin's ideas, inventions, and improvements are described. These things below all impacted society in some way.
Throughout this page, connections are made between the history behind his ideas and how science is not only used to create and make these ideas possible, but make them better in all aspects.


Example of Bifocal Lens
Ben Franklin was inspired to invent bifocals in 1784 after becoming tired of switching from two different types of glasses. His old age was making it difficult for him to see both up-close and far away. Franklin was able design a frame that included both types of lenses. The distance lens is placed at the top and the up-close lens is placed on the bottom. Franklin's original bifocals had only used convex lens, a least convex lens for distant objects and a most convex lens for close objects. Today the bifocal has improved, using a convex-concave lens that provides a better distinction between the two object distances. Now, a convex lens is used for far sightedness in conjunction with a concave lens for near sightedness. These types of lens are also known as meniscus lenses.
Today, correct lenses and bifocals uses a refraction index to determine the strength of lens one would need. This refraction index is found using the equation: n=c/v, where n=refraction index, c=speed of light (3.00 x 10⁸ m/s), and v=actual velocity of light through lens. A higher refraction index means more bending of light occurs.
Eyeglass lens are broken down into four categories, based on refraction index. The higher the refraction index, the stronger the lens.

  • Normal index - 1.48 ≤ n < 1.54
  • Mid-index - 1.54 ≤ n < 1.60
  • High-index - 1.60 ≤ n < 1.74
  • Very high index - 1.74 ≤ n

In the late 1700's only crown glass was used for eyeglasses, providing a natural refraction index of 1.52, which was difficult to change. Now in modern day, eyeglass industries use much more materials to create lenses that are not only more effective to different prescriptions, but are also safer. Some materials used today include:

  • Plastic - Refraction index of 1.498 (Easily changed to suit needs)
  • Trivex - Refraction index of 1.532
  • Polycarbonate - Refraction index of 1.586
  • Polyurethanes - Refraction index of 1.640 to 1.740 (Great High Index lenses)

Daylight Savings Time (DST):
"Early to bed, and early to rise, makes a man healthy, wealthy and wise" - Benjamin Franklin

Ben Franklin was the first one to suggest the use of Daylight Savings Time while he was serving abroad in Paris in 1748 in an essay, “An Economical Project”. The first person to consider the idea of Daylight Savings Time was a London builder by the name of William Willet, who wrote a pamphlet called “A Waste of Daylight”. His idea was to turn the clocks ahead twenty minutes each of the four Sundays in April, and then turn them back twenty minutes each of the four Sundays in September. Willet eventually advocated his ideas enough to get a bill introduced into the House of Commons. The Bill was often made fun of in Parliament. Although Willet died on March 4, 1915, an act was passed in Britain to add eighty minutes in separate intervals on March 17, 1916. The act was did not have widespread acceptance, and some people even ignored it altogether.
Since World War I, the United States and many European countries have used Daylight Savings Time. At this time in history, there was a need to conserve fuel that was used to produce electric power. Daylight Savings Time began on April 30, 1916 at 11:00 p.m. The hands of a clock were advanced on hour ahead until the following October. Other countries that participated in 1916 were: Belgium, Denmark, France, Italy, Luxembourg, the Netherlands, Norway, Portugal and Sweden among a few others.

Daylight Savings Time was formally adopted into United States Law on March 199,1918. This law allowed for standard time zones to be set and scheduled summer Daylight Savings Time to begin on March 31, 1918. Daylight Savings Time was practiced for seven months in 1918 and 1919, but became unpopular after the war ended, and was thus repealed with a Congressional override over President Wilson’s veto in 1919. From this point, Daylight Savings Time became a local option that remained in some states and cities such as Massachusetts, Philadelphia and Chicago. Franklin Roosevelt tried to institute Daylight Savings Time during World War II, but caused much more confusion and was not easily accepted.
It was not until 1966 that about 100 million Americans were observing Daylight Savings Time. Congress decided to establish a single pattern for DST throughout the country, and therefore, President Lyndon Johnson signed The Uniform Time Act of 1966 into Public Law 89-387 on April 12, 1966. The passing of this law declared that Daylight Savings time began the last Sunday of April and ended the last Sunday of October each year. If a state wanted to be exempt from this law, they could do so by passing a state law.
In 1972, the law was reviewed to discuss the observation of Daylight Savings Time in states that lied in more than one time zone. In 1986, the law was amended so that the first start in April would mark the beginning of Daylight Savings Time. This legislation declared that DST begins at 2:00 a.m. on the first Sunday of April and ends at 2:00 a.m. the last Sunday of April.

Currently, there are still debates on when DST should begin and end dealing with the issues of saving energy. Today in the United States, DST begins at 2:00 a.m. on the first Sunday of March and ends at 2:00 a.m. on the last Sunday of November. Overall, even through all the inconsistencies, it must be noted that Ben Franklin helped in institute an idea that is still working to serve people throughout the world today and most likely even years to come.

Ben Franklin suggested Daylight Savings Time for the simple fact that when there is more daylight, less energy should be consumed from lighting sources. Throughout the days with simple energy sources, such as lighting, the amount of kilowatt-hours in an average home were slightly less during daylight savings time. Now in the modern era where most technology uses energy, the benefits of DST diminish. Since most people use electronics, HVAC (heating, ventilation, air conditioning), etc during the day, there is more energy consumed during daylight than saved. So does DST really save energy? Pre- 20th century: yes. Post 20th century: no.

Furnace Stove (Franklin Stove):

Example of a Franklin Stove
Example of a Franklin Stove

Around 1744, Franklin invented the coal stove, which produced more heat with less coal consumption. This was one of the first attempts to create a warm air furnace, although the patent was given to Daniel Pettibone of Philadelphia, at the late date of 1808. This invention improved the efficiency of heating a room by increasing heat output and decreasing smoke output. It was also an important factor towards safety in the home; the iron walls not only absorbed the heat to save it for later, but also protected the surrounding wood.

The Franklin stove uses a cast iron base to lock in and maintain heat. It also featured metal baffles to improve the heating efficiency. This heating efficiency can now be found using conservation of energy. The heating efficiency of the heating engine (franklin stove) can be found using the equation:
e=Output/Input where:

  • e=efficiency of engine (dimensionless value between 0 and 1) - multiply by 100% to receive efficiency percent
  • Input=the amount of work used in engine (in Watts) or amount of energy used in engine (in joules)
  • Output=the amount of work released (in Watts) or amount of energy released (in joules)
The heating efficiency of the franklin stove was found to be about 70%, which is decent for a heating engine, even in today's time. Now, cast iron stove can reach an efficiency of 78 %. According to the Second Law of Thermodynamics, it is impossible to construct a heat engine that produces no other effect than the absorption of energy from a reservoir and the performance of an equal amount of work. This literally means that no engine in real life can produce a 100 % efficiency rate from input to output.

Glass Armonica:

Franklin's Armonica
After hearing a concert of Handel’s Water Music played on tuned wine glasses, Ben Franklin was inspired to create his own version of the armonica. Franklin created his own armonica in 1761. Franklin's re-creation was much smaller than the original and it did not need to be tuned. His armonica was popular in both England and America and both Mozart and Beethoven composed music with it. He enjoyed it so much that he gave the comment that,“Of all my inventions, the glass armonica has given me the greatest personal satisfaction."
The glass armonica relies solely on the friction and vibrations of the glass. To create different tune, different sizes of glass are vibrated. Deeper sounds are denoted by a lower frequency, while higher sounds require a higher frequency. The frequency of each glass tube is equally proportionate to its length, using the equation:
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Lightning Rod:
In the summer of 1747, Franklin accidentally shocked himself. This shock began a lifelong obsession with electricity, conducting experiments to learn more about its potential. As he conducted more experiments about electricity, he wanted to develop a method to protect people from the dangers of lightning. Lightning rods provide a low-resistance path to ground that can be used to conduct the enormous electrical currents when lightning strikes occur. From his studies, Franklin decided to create an eight foot long rod out of iron, with a sharpened tip, to essentially help ground the house. Franklin wrote in a letter, "
the electrical fire would, I think, be drawn out of a cloud silently, before it could come near enough to strike...," which describes the use of the lightning rod. The lightning rod moves electrical current away from the structure and safely to ground.

Because of Franklin's
observations with lightning, he was able to make many steps forward in the advancement of electricity. With these studies, Franklin was able to begin to describe the charges within electricity. Franklin first person to label charges "positive" and "negative". He developed a long theory of electricity, which deals with electricity being an invisible part in all matter. He also discovered that the electric charge can neither be created nor destroyed. This is now called the charge conservation, which was experimented further by James Clerk Maxwell, a well known scientist that began the electromagnetic theory.

Swim Fins:

Ben Franklin loved swimming as a young boy, and invented swim fans at the age of 11. His invention was much different than what we know today as swim fins. The fins strapped to the hands of the swimmer in order to make a more efficient stroke. The fins were constructed out of two wooden paddles.
Since swim fins have a larger surface area than feet or hands, they help create much more water displacement. This in turn creates much faster swimming with less force involved. Swim fins help even out the effects of drag in the water, which is a force
which is produced by the underwater waves in the water.
Example of modern day swim fins

The force of drag created by the fins can be found by using the drag equation, where:

  • Fd=Force of drag
  • Þ=density of fluid
  • v=velocity of object relative to the fluid
  • Cd=Drag coefficient
  • A=area of object

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