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Experiments and Observations on Electricity

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Title page of 1751 original publication

Experiments and Observations on Electricity is a mid-eighteenth century book consisting of letters from Benjamin Franklin. These letters concerned Franklin's discoveries about the behavior of electricity based on experimentation and scientific studies. The book came in pamphlet form for the first three English editions. The last two editions were in a book volume with hard covers and a book spine. There were eleven European editions of the book: five English editions, three French editions, and a German, Italian and Latin edition. The publication was well received worldwide. It was considered America's most important scientific book of the eighteenth century.

The book came about through the activities of scientists at the Royal Society of London. Franklin sent letters to members of the Society about his experiments on electricity and the observations he had made. Most of these letters went to Peter Collinson. Some of these were read at the society's meetings. There was much interest shown, so some of them were sent to a printer to be published in a magazine. Public interest in Franklin's letters about electricity led the Society to gather together many of the letters to Collinson from Franklin over a two-year period and send them to the printer for publication. This first collection of letters was published in a ninety-page pamphlet in 1751. It was soon followed by other parts that were "Supplemental" to the existing edition and eventually a "New" publication was sold from the total of all the "Parts" produced. Each edition expanded by additional Franklin letters being added. It ultimately became a 496-page volume by 1769. The book inspired others to follow in Franklin's footsteps to do further in-depth research on electricity.


Franklin's electrostatic machine
display at Franklin Institute museum.

Franklin was first attracted to the study of electricity when he saw the showman Archibald Spencer do magic demonstrations in Boston (1743) and in Philadelphia (1744).[1] He purchased Spencer's equipment and used it for his electricity experiments after these demonstrations were completed.[2] He referred to Spencer as Dr. Spence from Scotland.[3] In 1746, at the age of forty years, Franklin began turning over the affairs of his printing company to his business partner David Hall, and went into semi-retirement so he could carry out research on electricity; initially using Spencer's equipment.[4][5]

Peter Collinson – a wealthy Quaker cloth merchant, a Fellow of the Royal Society and one of the founders of the Society of Antiquaries of London – donated (in 1746) a Leyden jar battery, a glass tube,[6] and an account of new German experiments in electricity to the Library Company of Philadelphia (founded by Franklin). The account described how to make electricity from the glass tube.[7] Franklin first experimented with static electricity in the middle of 1747, referring to it as "these new wonders."[8] In conducting his initial electrical research, Franklin made use of the unique battery and glass tube provided by Collinson.[4]

Thomas Penn, son of William Penn, made an electrostatic machine that supplemented Collinson's equipment.[4] To these Franklin added an electrostatic generating machine of his own design that was more efficient than the one given to him by Penn.[6] It was convenient because it was constructed with a handle, like that of a common grindstone, and turned by the operator. The simple mechanical machine mechanism then spun an axle that had mounted on it a glass sphere that rubbed on a cloth pad.[9] The glass sphere bulb generated 'electric fire' (an electric charge) that was transferred through conductors to a Leyden jar capacitor that held the electric charge that was then used for experimentation.[10] Franklin formed a research core team that consisted of Ebenezer Kinnersley, Thomas Hopkinson, and Philip Syng and developed the first scientific research laboratory in America.[11] He repeated his experiments to obtain the same results and recorded this observation. In this process he showed that anyone could repeat and prove these results themselves of the electrical principle if they did the experiment he detailed.[9]

Franklin spent much time studying this new field of electricity, and from 1747 through 1750 sent many letters to Collinson on his findings. The book consists of a collection of these letters. The book came in pamphlet form for the first three editions. The last two editions were a book volume with hard covers. Franklin's letters explained his experiments and the observations he made from them. He sent these to Collinson to show that the equipment – put into the hands of the group of men associated with Library Company of Philadelphia – was being put to good use.[8]

William Watson, a scientist specializing in the study of electricity, theorized that perhaps electricity was attracted to conductors that were pointed.[12] Watson received in 1746 from Dr. John Mitchell a lengthy Franklin letter on theories about thunderstorms and pointed conductors as related to electricity. He read part of the letter to fellow members of the Royal Society of London on November 9, 1749. A week later he finished the reading. On December 4 Watson received another similar Franklin letter dated April 29, 1749, from Collinson and read it to the Society on December 21, 1749. Over the next two years Collinson had transmitted to the Society more of Franklin's letters he had received describing electrical experiments done by Franklin and his team of experimenters. Many talked about the tendency of an electrical discharge to be attracted to a pointed conductor that was grounded - the basics to his lightning rod invention to protect wooden buildings such as houses and churches.[13]

Watson turned over some of these Franklin letters to the local publisher Edward Cave, who had them printed in The Gentleman's Magazine in 1750.[14] In April 1751 Cave printed in a publication more of the letters Collinson had received and they included corrections personally added by Franklin.[15] This publication was titled, Experiments and Observations on Electricity, Made in Philadelphia in America by Mr. BENJAMIN FRANKLIN and Communicated in several letters to Mr. P. Collinson of London, F.R.S (London).[16] It was a 90-page pamphlet of 86 numbered pages.[17] The pamphlet included an unsigned preface written by Dr. John Fothergill.[18] This first publication of Experiments and Observations on Electricity sold for the expensive price of two shillings and sixpence British money, equivalent to £18 in 2015.[19]


Typical letter in the book - July 27, 1750.
Letter V in the first three English editions is
Letter VI in fourth and fifth English editions.

The eighteenth century book consists of a collection of letters and essays written by Franklin. Most of the 25 letters in the collection were to Collinson. Some had personal content, but most were about his experiments with electricity and what he had observed from them. These talked about the conclusions he came to after doing scientific experimentation on Leyden jars and lightning storm clouds. He many times related the similarities of how each of these acted and that the principles they followed were identical. This connection ultimately led Franklin to the lightning rod and that the electricity could be diverted harmlessly away from houses and wooden buildings - making it a protection device.[20][21]

There were five English editions to this book. The first three editions were not hard cover volumes, but rather just pamphlets with paper covers of collected letters of Franklin. They were carelessly put together when published. Each of these pamphlet editions had supplements of additional letters that were added later and then republished. The first publication of 1751 was supplemented in 1753 with 20 more pages and called Supplemental Experiments and Observations, Part II. It was numbered 89 to 109 and published by E. Cave. This was again supplemented with an additional 44 pages in 1754, numbered 110 to 154, and titled New Experiments and Observations, Part III. It was published by R. Cave, the son of E. Cave. The second edition published in 1754 was a reprint of parts I and II of the first edition. The third edition published in 1760, 1762, and 1764 was a reprint of all three parts of the first edition and numbered 1–154.[20][21]

In this first set of letters Franklin talked about electrical fire, later (1749) changing the terminology to electrical fluid.[22] He wrote to Collinson on June 5, 1747, that his experiments showed that the electrical fire was a new element of matter existing as particles in all ordinary matter.[23] Franklin determined that a friction rubbing process like that of rubbing glass with a cloth does not create these particles, but only temporarily groups them together so that they can be collected and held in a Leyden jar of water and metal.[24] According to Franklin, one side of the Leyden jar had an accumulation of electrical fire, which he labeled as positive (plus), and the other side had a deficiency of electrical fire, labeled negative (minus). These losses and gains of electrification were exactly equal and are essentially the modern law of charge conservation except that it is now recognized that negative charges exist in their own right, not just as a deficiency of positive charges.[25] It is an important principle in modern science that explains the microphysics of the electrification of gross bodies.[26] In these letters, Franklin introduced technical words that we use today for things related to electricity such as plus, minus, positive, negative, charge, discharge, armature, electric shock, electrician, condenser, conductor, and battery.[27][28]

Leyden jar "electric battery"

Franklin's first experiments explained in this first set of letters to Collinson that the Leyden jar, a type of capacitor, had equal and opposite charges on the inner and outer conductors.[29] This was shown in illustrations in his book.[29] The significant Franklin theory introduced to Collinson in a letter dated April 29, 1747, was the concept of the "dissectible condenser."[30] Today we call this distribution of charges in a device, a capacitor.[13] He observed that a charge was built up on both sides between a piece of nonconducting material.[31] In the case of the Leyden jar this was glass (nonconducting matter) and on each side of it was a metal material (conducting matter).[31] These opposite metal layers had the exact opposite electric charges (positive and negative).[31] He observed that when the wire on the inside of the jar was electrised positively by a certain amount, that the outer conductor simultaneously became electrised negatively in the same proportion.[31]

Franklin explained in these letters that in an experiment he did show that the charge was in the glass itself and not in the water within the jar, as had been theorized by others. After a Leyden jar was charged he poured the water from it into another Leyden jar that was not charged. It turned out the electric force was not condensed in the water itself, as the new Leyden jar had no charge with this water from the first Leyden jar. Then the first jar was refilled with fresh water and it was discovered that there was a charge in this jar. The conclusion then was that it was the glass itself that was the condenser of the electric force. It was further determined by more experimentation that it did not matter what shape the glass was in or if an object was shaped like a glass bottle.[32] It was finally determined that a property of the glass itself was this "force" of equal and opposite charges.[30][33]

Franklin further explains in these letters that the jar did not electrically balance itself, but a wire of some conducting material had to make contact from the inner conductor (plus) to the outer conductor (minus).[31] This way Franklin observed the balancing and combining of the two different states of electricity in the "miraculous bottle."[31] In the later editions of the book Franklin explained in his letters and showed in illustrations an assembly of Leyden jars that he termed "electrical battery" following the military term of the time of a "battery" being a group of cannons assembled together.[34][35] Franklin assembled a number of parallel-plate condensers consisting of 11 plates of glass and each were "armed" with a lead metal sheet on each side. He hooked them together with wires in a series and then a master wire was attached that could then discharge (balance) the battery when touched to both sides.[36]

Fourth edition volume increased to 496 pages.
Had hard covers and additions to third edition.
(Franklin's bifocal glasses shown on the book)

The fourth edition, published in 1769, is the first complete edition in one volume and had hard covers. He added footnotes to make certain issues clearer. In this edition he also added several of his own philosophical essays and completed the volume with an index. The fourth edition was a book volume with hard covers that increased the number of pages from 154 to 496. Franklin added papers on his lightning rod invention, meteorological observations, human nature, worldwide population increase, waterspouts, experiments on amber, and information on his Pennsylvania fireplace invention. This edition had copper plate illustrations of his lightning rod design, new fireplace, and electrical experiments. The fifth English edition was published in 1774. There was little difference between the fourth edition and the fifth edition. The only new document added in the fifth edition, that was not in the fourth edition, was the French experiment with lightning done in 1752. There was an advertisement in the Public Advertiser London newspaper of September 9, 1774, that promoted the fifth edition.[37]

The fourth English edition, published in 1769, was personally supervised by Franklin while visiting London from Philadelphia. He made several corrections on different parts of the first three editions and wrote explanatory notes. One important correction Franklin noted in the Forward was that Letters 1 and 2 had been transposed and he had corrected that. He added a letter that was important to him. It was a letter to Collinson dated March 28, 1747. Franklin had thanked him for the gift of the German "electric tube" with directions on how to use it to make electricity. He was much appreciative of this, so he made that particular one Letter #1. This then advanced the numbering sequence of the Letters by one from the first three editions.[38]


Second edition 1754 of New Experiments of Part I and Part II

There were eleven editions of Experiments and Observations on Electricity. There were five English editions, three French editions, and an edition each in German, Italian and Latin. The first three English editions were similar, but not identical, and consisted of two or three parts. Each of these separate parts were printed and sold individually as a pamphlet. Each had a slight title change (i.e. "New", "Supplemental") apparently to promote selling additional copies to people that had bought before.[39]

  • English edition 1.1 printed April 1751 (pages #1 - 88) and sold by E. Cave at St. John's Gate.[20]
  • English edition 1.2 printed 1753 (Supplemental Ex ...) and sold by E. Cave at St. John's Gate.[20]
  • English edition 1.3 printed 1754 (New Experiments) and sold by D. Henry at St. John's Gate.[20]
  • English edition 2.1 printed 1754 (New Experiments) and sold by R. Cave at St. John's Gate.[20]
  • English edition 2.2 printed 1754 (New Experiments) and sold by D. Henry at St. John's Gate.[20]
  • English edition 3.1 printed in 1760 (pages #1 - 154) and sold by D. Henry at St. John's Gate.[20]
  • English edition 3.2 printed in 1762 (pages #1 - 154) and sold by R. Cave at St. John's Gate.[20]
  • English edition 3.3 printed in 1764 (pages #1 - 154) and sold by R. Cave at St. John's Gate.[20]
  • English edition 4.0 printed in 1769 for D. Henry and sold by F. Newberry at St. Paul's church.[40]
  • English edition 5.0 printed in 1774 for F. Newberry and sold by him at St. Paul's churchyard.[40]

Reception in France[edit]

1752 French edition

The French translation, published in 1752, contained an experiment suggesting that a long, pointed iron rod would attract a lightning bolt from a thunderstorm cloud.[41] In 1750 Hopkinson suggested to Franklin the concept that electricity is attracted to points. Franklin then carried the idea a step forward and surmised that a pointed iron rod high above a rooftop would attract a lightning bolt, if the bolt was of electricity.[42] Frenchman Thomas-Francois d'Alibald did the actual experiment May 10, 1752, as Franklin had suggested and lightning struck the iron rod.[41][43] In London it was repeated in Spital Square on July 20, 1752, and again in Chelmsford, Essex, on August 12, 1752.[44][45] The electricity attraction from a lightning storm was also done by Franklin himself in the kite experiment that he talked about in a letter to Collinson dated October 19, 1752.[44] A man by the name of G. W. Richman was killed in 1753 from electrocution doing the kite experiment.[46] Franklin had proven that lightning bolts and electricity were one and the same.[46] He also showed that this "electric fluid" was attracted to a sharply pointed object high in the sky.[45] An iron rod could have the other end put into the ground to create a path for safe conduction of the high voltage electricity.[47] Thus, a way of diverting lightning bolts from wooden buildings – and preventing them from going aflame due to lightning hits – had been discovered.[48] Franklin's lightning conductor invention, with its lightning rod uppermost point, became a model for the lightning-protection system used in America in the eighteenth century.[49]

King Louis XV honored Franklin after seeing some of the electrical experiments done in the royal palace at St. Germain near Paris, France. However physicist Jean-Antoine Nollet (1700–1770), a skeptic who had published his own theory on electricity, declared Franklin's ideas were wrong.[50] He claimed in 1753 that Franklin's lightning rod was not only dangerous but useless and would attract lightning bolts to wooden buildings, causing them to be hit more often. Franklin in time proved to the scientific community that his lightning rod invention not only was a protective device,[51] but it also served as a preventive way to divert destructive lightning bolts away from hitting buildings.[52]


All editions of the book were being printed in Europe until 1941, when the first publication of it was done in the United States by I. Bernard Cohen.[53] The book is Franklin's only scientific work,[54] and is recognized by historians Gary F. Kurutz and Dennis Smith as America's most important scientific book of the eighteenth century.[55][56] The publication for his scientific observations on electricity made Franklin famous throughout Europe as a serious scientist.[29] Eighteenth-century British polymath Joseph Priestley writes in his book The History and Present State of Electricity (1767) that nobody had written an in-depth study of electricity with the use of scientific experimentation like this of Franklin's that had been translated into most European languages in the eighteenth century.[A]

Benjamin Franklin was given the Copley Medal by the Royal Society in 1753 in recognition of his work in electricity as reported in this book.[57] [58][59] He became a Fellow of the Society after his name was submitted the required ten times (one included the Society's president, Lord Macclesfield).[60] Also he was given an honorary degree at the College of William and Mary in 1756 and elected into the French Academy of Science in 1772 because of this book.[61] The theories that Franklin developed in the book formed the basis for subsequent research on electricity.[48]

See also[edit]



  1. ^ "Priestley declares in his History and Present State of Electricity: Nothing was ever written upon the subject of electricity which was more read and admired in all parts of Europe than these letters. There is hardly any European language into which they have not been translated; and, as if this were not sufficient to make them properly known, a translation of them has been lately made into Latin."[39]


  1. ^ Benge & Benge 2005, p. 106.
  2. ^ Benge & Benge 2005, p. 107.
  3. ^ Cohen 1990, p. 42.
  4. ^ a b c Campbell 1999, p. 53.
  5. ^ Stewart 1992, p. 57.
  6. ^ a b Lemay 2009, p. 75.
  7. ^ Stearns 1970, p. 620.
  8. ^ a b Campbell 1999, p. 54.
  9. ^ a b Campbell 1999, p. 55.
  10. ^ Hillis, Newell (February 16, 1914). "The Quest of God". Brooklyn Daily Eagle. Brooklyn, New York – via open access.
  11. ^ Campbell 1999, pp. 53–54.
  12. ^ Cohen 1975, p. 49.
  13. ^ a b Cohen 1975, p. 41.
  14. ^ Tucker 2009, p. 81.
  15. ^ Cohen 1941, p. 92.
  16. ^ Stearns 1970, pp. 619–620.
  17. ^ "From Benjamin Franklin to Peter Collinson, 28 March 1747". Founders Online. National Historical Publications and Records Commission. Archived from the original on 28 October 2016. Retrieved July 12, 2015.
  18. ^ Cohen 1956, pp. 432, 478.
  19. ^ Lemay 2009, p. 96.
  20. ^ a b c d e f g h i j "Letter From Benjamin Franklin to Peter Collinson, 28 March 1747". Founders Online. National Historical Publications and Records Commission (NHPRC). 2016. Retrieved March 14, 2017.
  21. ^ a b New experiments and observations on electricity : made at Philadelphia in America (Notes section). Thomson Gale. 2005. OCLC 942611109.
  22. ^ Cohen 1990, p. 56.
  23. ^ Cohen 1956, p. 450.
  24. ^ Cohen 1956, p. 450–454.
  25. ^ Cohen 1990, p. 26-27.
  26. ^ Cohen 1975, pp. 49–50.
  27. ^ Cohen 1975, p. 40.
  28. ^ Wilson 1960, p. 19.
  29. ^ a b c Cohen 1975, p. 12.
  30. ^ a b Cohen 1975, p. 52.
  31. ^ a b c d e f Cohen 1975, p. 51.
  32. ^ Wilson 1960, p. 21.
  33. ^ Cohen 1956, p. 452–465.
  34. ^ Cohen 1956, pp. 462.
  35. ^ Cohen 1975, p. 24–25.
  36. ^ Cohen 1975, p. 53.
  37. ^ "Note on the Fourth and Fifth Editions of Experiments and Observations". Founders Online. US National Archives. 2017. Retrieved March 15, 2017.
  38. ^ Cohen 1941, pp. 149–170.
  39. ^ a b Cohen 1941, pp. 139–140.
  40. ^ a b Cohen 1941, pp. 141–144.
  41. ^ a b Tucker 2009, p. 82.
  42. ^ Stearns 1970, p. 624.
  43. ^ Benge & Benge 2005, p. 126.
  44. ^ a b "ATMOSPHERIC ELECTRICITY". The Manning Times. Manning, South Carolina. December 25, 1907 – via open access.
  45. ^ a b "Experiment suggested by Franklin and performed by D'Alibald". Covina Argus. Covina, California. November 30, 1907 – via open access.
  46. ^ a b "Nature". Newport Mercury. Newport, Rhode Island. March 28, 1896 – via open access.
  47. ^ Doren 1948, p. 56.
  48. ^ a b Morgan 2003, pp. 13–14.
  49. ^ Schiffer 2003, pp. 185–194.
  50. ^ Nollet, Jean-Antoine (January 1, 1753). "Jean-Antoine Nollet: Letters on Electricity". NHPRC. US government National Archives. Retrieved February 17, 2017.
  51. ^ "Polytechnic get some rare books". Brooklyn Daily Eagle. Brooklyn, New York. March 11, 1913 – via open access.
  52. ^ Schiffer 2003, pp. 192.
  53. ^ Purvis 2014, p. 273.
  54. ^ Rosenberg 2009, p. 212.
  55. ^ Kurutz 1980, p. 212.
  56. ^ Smith 2006, p. 181.
  57. ^ "A Man Who Dared Lightning". The Chatham Press. Chatham, New Jersey. December 26, 1974 – via open access.
  58. ^ Cohen 1956, p. 491.
  59. ^ "Awarded Copley metal". World of Influence. Twin Cities Public Television. 2002. Retrieved July 14, 2015.
  60. ^ Cohen 1975, p. 28.
  61. ^ Haugen 2005, p. 62.


External links[edit]

A copy of the first 1751 pamphlet with annotations in Franklin's hand is available on Internet Archive:

There is also summary information including a table of contents available at Founders Online:

Each of the documents from the first 1751 edition is also available on Founders Online with many explanatory notes: