Benjamin Franklin and ElectricityHis greatest fame as a scientist was the result of his discoveries in electricity. On a visit to Boston in 1746 he saw some electrical experiments and at once became deeply interested. A friend, Peter Collinson of London, sent him some of the crude electrical apparatus of the day, which Franklin used, as well as some equipment he had purchased in Boston. He wrote in a letter to Collinson: "For my own part, I never was before engaged in any study that so engrossed my attention and my time as this has lately done."
Benjamin Franklin's letters to Peter Collinson tell of his first experiments about the nature of electricity. Experiments made with a little group of friends showed the effect of pointed bodies in drawing off electricity. He decided that electricity was not the result of friction, but that the mysterious force was diffused through most substances, and that nature is always restored its equilibrium. He developed the theory of positive and negative electricity, or plus and minus electrification.
The same letter tells of some of the tricks which the little group of experimenters were accustomed to play upon their wondering neighbors. They set alcohol on fire, relighted candles just blown out, produced mimic flashes of lightning, gave shocks on touching or kissing, and caused an artificial spider to move mysteriously.
Lightning and ElectricityBenjamin Franklin carried on experiments with the Leyden jar, made an electrical battery, killed a fowl and roasted it upon a spit turned by electricity, sent a current through water to ignite alcohol, ignited gunpowder, and charged glasses of wine so that the drinkers received shocks.
More important, perhaps, he began to develop the theory of the identity of lightning and electricity, and the possibility of protecting buildings by iron rods. Using an iron rod he brought down electricity into his house, and studied its effect upon bells, he concluded that clouds were generally negatively electrified. In June of 1752, he performed his famous kite experiment, drawing down electricity from the clouds and charging a Leyden jar from the key at the end of the string.
Benjamin Franklin's letters to Peter Collinson were read before the Royal Society which Collinson belonged to but were unnoticed. Collinson gathered them together, and they were published in a pamphlet which attracted wide attention. Translated into French, they created great excitement, and Franklin's conclusions were generally accepted by the scientific men of Europe. The Royal Society, tardily awakened, elected Franklin a member and in 1753 awarded him the Copley medal with a complimentary address.
Science During the 1700sIt may be useful to mention some of the scientific facts and mechanical principles which were known to Europeans at this time. More than one learned essay has been written to prove the mechanical indebtedness of the modern world to the ancient, particularly to the works of those mechanically minded Greeks: Archimedes, Aristotle, Ctesibius, and Hero of Alexandria. The Greeks employed the lever, the tackle, and the crane, the force-pump, and the suction-pump. They had discovered that steam could be mechanically applied, though they never made any practical use of steam.