Benjamin Franklin Inventions

Benjamin Franklin was an American polymath and one of the Founding Fathers of the United States.

Franklin was a prodigious inventor. Benjamin Franklin inventions include the lightning rod, glass harmonica, Franklin stove, bifocal glasses and urinary catheter.

In 1748 he constructed a multiple plate capacitor. He placed eleven panes of glass sandwiched between lead plates, suspended with silk cords and wires and called it an “electrical battery”.

Franklin was the first to label them as positive and negative respectively, and he was the first to discover the principle of conservation of charge. Franklin briefly investigated electrotherapy, including the use of the electric bath.

Benjamin Franklin Inventions – Kite Experiment 

The kite experiment is a scientific experiment in which a kite attached with conductive wire on its apex. Benjamin Franklin flown it near thunder clouds to collect electricity from the air and conduct it down the wet kite string to the ground.

Benjamin Franklin Inventions - Kite Experiment 
Benjamin Franklin Inventions – Kite Experiment

It was proposed and may have been conducted by Benjamin Franklin with the assistance of his son William Franklin.

The experiment’s purpose was to uncover the unknown facts about the nature of lightning and electricity, and with further experiments on the ground, to demonstrate that lightning and electricity were the result of the same phenomenon.

Benjamin Franklin Inventions – Bifocal Lens

Benjamin Franklin is generally credited with the invention of bifocals. Historians have produced some evidence to suggest that others may have come before him in the invention.

However, a correspondence between George Whatley and John Fenno, editor of the Gazette of the United States, suggested that Franklin had indeed invented bifocals, 50 years earlier originally thought.

Benjamin Franklin Inventions – Franklin Stove 

Benjamin Franklin invented the Franklin stove in 1741, which is a metal-lined fireplace. It had a hollow baffle near the rear (to transfer more heat from the fire to a room’s air) and relied on an “inverted siphon” to draw the fire’s hot fumes around the baffle.

Benjamin Franklin intended to produce more heat and less smoke than an ordinary open fireplace.  It achieved few sales until David Rittenhouse improved it. It is also known as a “circulating stove” or the “Pennsylvania fireplace”.

Benjamin Franklin Inventions – Atlantic Ocean currents

As deputy postmaster, Franklin became interested in the North Atlantic Ocean circulation patterns.

While in England in 1768, he heard a complaint from the Colonial Board of Customs: Why did it take British packet ships carrying mail several weeks longer to reach New York than it took an average merchant ship to reach Newport, Rhode Island?

Franklin put the question to his cousin Timothy Folger, a Nantucket whaler captain, who told him that merchant ships routinely avoided a strong eastbound mid-ocean current.

The mail packet captains sailed dead into it, thus fighting an adverse current of 3 miles per hour (5 km/h).

Later Franklin worked with Folger and other experienced ship captains. He learning enough to chart the current and name it the Gulf Stream, by which it is still known today.

It took many years for British sea captains to adopt Franklin’s advice on navigating the current; once they did, they were able to trim two weeks from their sailing time.

In 1853, the oceanographer and cartographer Matthew Fontaine Maury noted that while Franklin charted and codified the Gulf Stream

Benjamin Franklin Inventions – Oceanography findings

An aging Franklin accumulated all his oceanographic findings in Maritime Observations, published by the Philosophical Society’s transactions in 1786.

It contained ideas for sea anchors, catamaran hulls, watertight compartments, shipboard lightning rods and a soup bowl designed to stay stable in stormy weather.

Benjamin Franklin Inventions – Concept of cooling

Franklin noted a principle of refrigeration by observing that on a very hot day, he stayed cooler in a wet shirt in a breeze than he did in a dry one.

To understand this phenomenon more clearly Franklin conducted experiments. In 1758 on a warm day in Cambridge, England, Franklin and fellow scientist John Hadley conducted experiment.  They continually wetting the ball of a mercury thermometer with ether and using bellows to evaporate the ether.

With each subsequent evaporation, the thermometer read a lower temperature, eventually reaching 7 °F (−14 °C). Another thermometer showed that the room temperature was constant at 65 °F (18 °C).

In his letter Cooling by Evaporation, Franklin noted that, “One may see the possibility of freezing a man to death on a warm summer’s day.”

Benjamin Franklin Inventions – Population Studies

Franklin had a major influence on the emerging science of demography, or population studies.

In the 1730s and 1740s, Franklin began taking notes on population growth. He found that the American population had the fastest growth rate on earth.

Emphasizing that population growth depended on food supplies, Franklin emphasized the abundance of food and available farmland in America. He calculated that America’s population was doubling every twenty years and would surpass that of England in a century

Benjamin Franklin Inventions – Decision-making

In a 1772 letter to Joseph Priestley, Franklin lays out the earliest known description of the Pro & Con list, a common decision-making technique, now sometimes called a decisional balance sheet

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