... Aurora . ... Electrons . ... Experiments with beams of negative particles were performed in Britain by Joseph John ("J.J.") Thomson, and led to his conclusion in 1897 that they consisted of lightweight particles with a negative electric charge, nowadays known as electrons. ... To mark the 100th anniversary of the discovery of the electron, the Center for History of Physics of the American Institute of Physics has created on the world wide web a suitable exhibit: http://www.aip.org/history/electron ....