THE GAS DISCHARGE PHYSICS IN THE 18th CENTURY – by Julia Cipo, Holger Kersten – Francis Edmond Hauksbee Halley * 1666 in Colchester, Great Britain † April/ May 1713 in London * November 8th, 1656 in Haggerston, London † January 25th, 1742 in Greenwich Francis Hauksbee was a british scientist, lab assistant of Isaac Newton *4 and an elected member of the Royal Society for researches in science. Edmond Halley was a british astro- ric (height) formula. In 1716 a bright physicist, meteorologist, mathemati- Aurora Borealis (Northern Lights) ing from the North Pole to the South Inspired by Picard’s and Bernoulli’s results on the luminosity of mercu- cian and member of the Royal So- was sighted in Germany, England, Pole. Even though this wasn’t correct, ry in barometric tubes, Hauksbee continued experimenting with mercu- ciety. As the earth’s magnetic fi eld France and Holland. Halley began he determined that the aurora’s arc ry with one difference: he examined the probe in a vacuum vessel. In fascinated him, he worked on this searching for a scientifi c explana- did not course along the geographic his 1709 publicated work topic during the years 1683-1710 tion of this phenomena. He suggest- pole, but along the magnetic pole. *1 called “Physio-mechanical and discovered the line profi le of the ed that the aurora was caused by an experiments on various Hauksbee’s generator magnetic fi eld as well as the baromet- evaporation of magnetic liquid mov- subjects touching light and electricity” he described that after placing mercu- ry in the glass vessel and then evacuating the air, a bright glow could be sight- ed. Hauksbee also noticed that the generated light could be used to read by. These researches led lat- er to the development of *5 gas-discharge lamps such *2 as neon-lightning lamps. *3 Hauksbee’s fi rst electric machine Gas discharge lamps Aurora Borealis Pieter van Benjamin Musschenbroek Franklin * January 17th, 1706 on the Governor‘s Island, Boston *8 * March 14th, 1692 in Leiden, Netherlands † 17th April, 1790 in Philadelphia, Pennsylvania † September 19th, 1761 in Leiden, Netherlands Benjamin Franklin was a politician, described his kite experiment: nished will not be damaged by light- Pieter van Musschenbroek was a dutch scientist, a student of Isaac Newton and scientist, printer and author. He “The method is this: Provide a small ning, it being attracted by the points, a fellow of the Royal Society. In 1746 van Musschenbroek invented the fi rst ca- played a crucial role in the politics iron rod (it may be made of the rod- and passing thro the metal into the pacitor, which was named “the Leyden jar” after the city of Leiden. The early of North America by co-writing the iron used by the nailers) but of such ground without hurting any thing. “ Leyden-jars consisted of a glass bottle fi lled with a small amount of water. A Independence Declaration of Ameri- a length, that one end being three This way he has explained the prin- cork with a vertical wire was positioned on the top, so the cork would close the ca. His requirement of solving prob- or four feet in the moist ground, the ciple of gas discharges. Franklin also bottle and the metal would dip into water. The exposed end of the wire was con- lems led him to his most well-known other may be six or eight feet above invented the terms ‘positive’ and nected to a friction device, which generated static electricity. After removing the discovery: the lightning rod. In a the highest part of the building... If ‘negative’ as well as the Franklin wire from the electricity source, the leyden jar would save the static electricity. By 1753 edition of his own published the house or barn be long, there may Stove, which is still used nowadays touching the loose end of the wire with the hand, a discharge would be noticed almanack “Poor Richard Almanack”, be a rod and point at each end, and and heated a room more effi ciently by receiving a shock. The design where news about the weather and a middling wire along the ridge from and safely than a fi replace did. the meteorology were published, he one to the other. A house thus fur- of the Leyden jars was being im- *6 proved. So the water has been replaced by an inner metal foil, which was connected to the metal wire in the inside. The outside of the jar would also be coated by a metal foil, which served as an electrode and is brought into contact with earth. This way it would not be anymore necessary to touch the metal wire to cause a discharge. To prove that the Leyden jar would stock the discharge, the charged bottle was being segmented into the glass part and the two thin metal foils. After the parts are put together a large spark can be received. This also showed, that the actual elec- tricity storage place is the glass part of the jar. The Leyden jars have *9 *10 *11 been used by Benjamin Franklin, Georg C. Lichtenberg and other scientists for their experiments. Constructions of lightning rod Franklin’s The kite experiment *7 for the Maryland State House lightning rod Leyden jar with metal foils Georg Christoph Joseph Lichtenberg * July 1st, 1742 in Ober-Ramstadt, Germany Priestley † February 24th, 1799 in Göttingen, Germany *15 * March 24th, 1733 in Yorkshire, Great Britain Georg Christoph Lichtenberg was a his memoirs “Super Nova Methodo ionized gas and † February 6th, 1804 in Pennsylvania german mathematician, natural sci- Naturam ac Motum Fluidi Electrici In- the dielectric sur- entist, member of the Royal Society vestigandi”. By applying a high volt- face of the materi- and the fi rst german professor for age charge to an insulating material al. The length of the Joseph Priestley was an english theologian, experimental physics. as glass and then by sprankling its sur- branchings can be chemist, member of the Royal Society and nat- He was among the fi rst to bring the face with sulfur and lead powder, he varied by changing ural philosopher. He had a few meetings with Franklin’s lightning rods to Germany noticed some characteristic patterns. the applied voltage Benjamin Franklin, who encouraged him to or as he called them “the frightening The patterns for the positive charge or the surrounding summarize his work in the book “The History *12 rods”, using several of them on his were longer with more branching, air pressure. and Present State of Electricity” published in home. Lichtenberg also constructed while the ones for the negative charge 1767. There he investigated that the electrical discharge did Lichtenberg the electrophorus, a large electro- were shorter and more compact. not acquire a charge, it would be enough if a insulated con- fi gures static generator to study the patterns These typical patterns are known as ductor was near a static electric device. With the help of his left from the lightnings. the Lichtenberg Figures. They are brother he constructed an electrical machine and investigat- His results were published 1777 in a product of interactions between ed the discharges of electrical charges through iron. *16 Sources: 1- Illustration of the Hauksbee generator “Physico Mechanical Experiments” 1719, 2- Alchetron- Free Social Encyclopedia, 3- Wikimedia, Work of Heinrich Pniok, 4- staff.science.uu.nl , 5- suntrek.org, 6- de.academic.ru, 7- Engineering Search Engine http://emadrlc.blogspot.de/, “The History and 8- Axia Public Relations, 9- Maryland State Archives, 10- The Pennsylvania Center for the Book, 11- likesuccess.com, 12- Scan of a print found in Wikimedia. Original is housed at the National Portrait Gallery, London., 13- Medical Historical Library of Yale University, 14- taringa.net,m 15- *13 Priestley’s Present State of uni-goettingen.de ( Georg-August-University of Göttingen, Germany), 16- scientifi csonline.com electrical machine Electricity” *14 .