Franklin, Benjamin (1706-1790)US scientist, inventor, statesman, diplomat, writer, printer, and publisher. He proved that lightning is a form of electricity, distinguished between positive and negative electricity, and invented the lightning conductor. He was the first US ambassador to France 1776-85, and negotiated peace with Britain in 1783. As a delegate to the Continental Congress from Pennsylvania 1785-88, he helped to draft the Declaration of Independence and the US Constitution. He was president of the first US abolitionist society in 1775 and was responsible for many improvements in American life, including a modernized postal system, and the first US fire and police departments, hospital, and insurance company. Franklin was born in Boston, the son of a soap and candlemaker, and the 15th of 17 children. After two years at school he was apprenticed to a printer at the age of 12, being self-taught from that time. In 1723, he left Boston for Philadelphia and in 1724 sailed for England, where he worked for 18 months in a printer's office. He returned to Philadelphia in 1726, set up his own printing business, and bought the Pennsylvania Gazette. In 1737, he became deputy postmaster of Philadelphia, and was a member of the colony's legislative body 1751-64. As early as 1754, Franklin was advocating an inter-colonial union to improve the presentation of colonial claims to the British government. Printing and publishing interests Franklin was apprenticed to his half-brother James, a printer and publisher of The New England Courant, to which Franklin secretly contributed. During this time he set about educating himself by studying at night after work. He continued to work in the printing trade after his move to Philadelphia in 1723, and was encouraged by the governor of Pennsylvania, who took an interest in him. In 1724 he went to England, where he used his printing skills to earn a living for 18 months. He returned to Philadelphia in 1726 and, after two years of hard work, set up his own printing business with a partner, with whom he co-founded the Pennsylvania Gazette, a weekly newspaper. In 1728 Franklin became sole proprietor of the newspaper, and in 1730 he married in 1730. He gradually became successful in business and was made an official printer for Pennsylvania and later Maryland. By 1748 Franklin had earned enough money to leave the printing business and he moved with his family to a farm in New Jersey, devoting his time to science and public service. |
| As proprietor of the Pennsylvania Gazette, Franklin is best remembered for Poor Richard's Almanack (1732-57), a collection of articles and advice on a huge range of topics, ‘conveying instruction among the common people’. The publication was a great success and brought Franklin a considerable income. Many of its sayings praising common sense, hard work, and honesty have become standard American proverbs; for example, ‘Early to bed, early to rise, makes a man healthy, wealthy and wise’. |
Public service Public affairs also proved to be a speciality and gradually Franklin became enmeshed in all sorts of progressive undertakings. He continued his disciplined regime of late night study, and took a strong interest in education. An academy founded on some of his educational principles later became the University of Pennsylvania. In 1727 he founded a debating club for aspiring traders called the Junto, which opposed slavery and evolved into the American Philosophical Society in 1743. In 1731, backed by this group, he started the first circulating library in America. He also formed Philadelphia's first volunteer fire company and raised money for the organizing of the first hospital in America. As deputy postmaster of Philadelphia 1737-53, he made many innovations, including the weekly delivery of mail. He was a clerk of the Pennsylvania Assembly 1736-51 and a member of the colony's legislative body 1751-64. |
Statesman and diplomat Franklin became concerned with the government of the colony from Britain, and by 1754 was advocating unified action between the colonies in their dealings with the British government. He was sent to Britain in 1757 as the Agent of the Pennsylvania Assembly to persuade the owners of Pennsylvania, the London-based Penn family, to pay their share of war expenses, and to lobby Parliament about tax grievances. He stayed on and off in Britain until 1775, attending meetings of the Royal Society (Britain's oldest and most eminent scientific society), as well as campaigning for the independence of the American colonies as their leading spokesperson. When, England passed the Stamp Act in 1765 (the first direct stamp tax on the colonists), Franklin acted as a diplomatic statesman, and helped to secure its repeal in 1766. On his return to the USA, Franklin helped to draft the Declaration of Independence in 1776 and was one of its signatories. He then travelled to France to enlist help for the American cause in the Revolutionary War that followed, successfully organizing nearly all outside aid. He played a central part in the negotiation of the peace with Britain, in 1783 signing the Treaty of Paris that guaranteed independence; he remained in Paris as US ambassador until 1785. Franklin, although now well over 70, continued to play an active part in the affairs of the new nation; in 1787 he guided the Constitutional Convention to formulate and ratify the US Constitution. After independence he became president of the state of Pennsylvania and worked hard to abolish slavery |
Abolitionist Franklin was a progressive thinker and his views on social reform evolved throughout his life. Although he had owned and sold slaves in his younger years, he came to believe that slavery was morally wrong. As early as 1727, the Junto (a debating club he founded for aspiring trades people) was conspicuously opposed to slavery, and by 1772, while living in England, Franklin explicitly condemned the institution of slavery in a tract entitled The Sommersett Case and the Slave Trade. On his return to Philadelphia in 1775, Franklin and Benjamin Rush, a distinguished physician and leader of the civilian temperance movement, founded the first American antislavery society, which was organized in Philadelphia under the title of ‘The Society for the Relief of Free Negroes, Unlawfully Held in Bondage’. The society became the first organized effort for the immediate abolition of African-American slavery in America, with Franklin as its president. In 1789, having finally returned to live in the USA, Franklin urged the public against accepting the institution of slavery in a speech addressed to the American Congress, writing that, ‘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’. His last public address was a scathing satire against slavery that compared its horrors with those of past civilizations. |
Scientist Franklin first began to commit more time to his scientific interests in 1746, when his business as a publisher was booming. Initially his thoughts turned to electricity, and he spent the next seven years executing a remarkable series of experiments; it was said that he found electricity a curiosity and left it a science. His later activities as a public servant, statesman, and diplomat by no means affected his scientific investigations, and during his visits as a colonial representative to Britain 1757-75, he frequently attended meetings of the Royal Society (Britain's oldest and most eminent scientific society). He was awarded the Copley Medal of the Royal Society in 1753, and was elected to the Society in 1756. |
The nature of electricity and the capacitor Franklin believed that electricity was a single fluid that flows into or out of objects to produce electric charges. This naturally led to the introduction of the terms positive and negative, a positive charge being an excess of electricity and a negative charge being a deficiency of electricity. Franklin had no way of knowing in which direction the electric fluid moved and made an arbitrary choice of which bodies became positive and which negative. In fact, electric charge moves to his negatively charged bodies, which is why the electron is given a negative charge. Franklin also made a fundamental discovery when he realized that the gain and loss of electricity must be balanced - the concept of conservation of charge. His ‘one-fluid’ theory , the notion that the so-called electrical fire is fundamental to all matter, brings scientific theory right up to the 20th century. |
| Franklin used one of the first capacitors, the Leyden jar (a glass jar lined with foil inside and out), as a proving ground for the clarification of his ideas. Franklin was able to show that the two coatings were oppositely charged, and that one had to be earthed while the other was being electrified. He finally demonstrated that ‘the power is in the glass’ - an appreciation of the importance of the dielectric later to be fully discussed by Michael Faraday. This work led to the first plate condenser or capacitor, which contained glass sheets between lead plates, called the Franklin panes. This device simplified electrical experiments by allowing the glass and lead components to be separated and increased in number, and gave rise to a ‘battery’ of condensers. |
Lightning These fundamental ideas led to Franklin's most famous work of all - that on lightning - and his invention of the lightning conductor. Although not the first to wonder about thunder and lightning in connection with electricity, Franklin showed that thunderclouds are indeed seats of electric charge whose behaviour is like charged bodies and that pointed conductors can dissipate the charge or carry it to earth safely. |
| The sentry-box or Philadelphia experiment, devised by Franklin and first performed in France in 1752, caused a sensation. A man on an insulating base stood inside a sentry box, which had a pointed rod 10 m/33 ft long fixed to its roof and insulated from it. The box itself was sited on a high building. Franklin suggested that a man could draw charge from a thundercloud by presenting an earthed wire to the rod, the man being protected by a wax handle. Sparks a few centimetres long were obtained. |
| Later that year, Franklin himself carried out his famous experiments with kites. By flying a kite in a thunderstorm, he was able to charge up a Leyden jar and produce sparks from the end of the wet string, which he held with a piece of insulating silk. The lightning conductor used everywhere today owes its origin to these experiments. Some of Franklin's last work in this area demonstrated that, although most thunderclouds have negative charges, a few are positive - something confirmed in modern times. |
| Franklin's interest in atmospheric electricity led him to recognize the aurora borealis as an electrical phenomenon, postulating good conditions in the rarefied upper atmosphere for electrical discharges, and speculating on the existence of what we now call the ionosphere. |
Physics Franklin was also influential in areas of physics other than electricity. Unfashionably for the time, he rejected the particle theory of light, being unable to account for the vast momentum that the particles should possess if they existed. This view inspired Thomas Young's fundamental work on the wave theory early in the following century. The concept of light particles having momentum was used by Louis de Broglie to establish the wave nature of the electron. |
| But in considering heat, Franklin's views were less helpful to the course of science. Franklin suggested a famous experiment to demonstrate conductivity in which rods of different metals are heated at one end and wax rings placed at the same distance along the rods fall off at different times as heat spreads through the rods at different rates. This led Franklin to speculate that heat is a fluid-like electricity, and aided development of the erroneous caloric theory of heat. |
The Gulf Stream Always interested in the sea, Franklin produced the first chart of the Gulf Stream following observations made in 1770 that merchantmen crossed the Atlantic Ocean from east to west in two weeks less than the mail ships - the former keeping to the side of the current, not fighting it. In 1775, he used a thermometer to aid navigation in the warm waters of the Gulf Stream and devised ways of measuring the temperature at a depth of 30 m/98 ft. |
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