Atmospheric electricity. Franklin’s experiments
About the middle of the eighteenth century the American scientist, Benjamin Franklin, came to the conclusion that lightning was a gigantic electric spark discharge occurring between two charged clouds or between a cloud and the earth. He had previously shown that it was possible to draw electricity from clouds by sending up a kite during a thunderstorm. The kite was anchored by a length of twine tied to a metal key. Attached to the key was a length of insulating silk ribbon whichFranklin held in his hand while he stood in a doorway to keep the silk dry. After the twine had been wetted by rain it became a conductor, and Franklin wasable to draw electric sparks from the key.
Being acquainted with point action, Franklin next suggested that a vertical insulated iron rod ought to become charged when a thundercloud passes over it. Without realizing the danger to which they were exposing themselves, a number of experimenters successfully tried out this experiment, using long pointed iron rods set up on the tops of high buildings. However, enthusiasm for this kind of research waned after the death, in 1753 of the scientist Georg Richmann, who was killed in Russia when his rod was struck by lightning.