Ernest Rutherford

Ernest Rutherford, right, sits with Hans Geiger beside their apparatus in Geiger's laboratory at the University of Manchester. Most archive records date the print to 1912, though copies are labeled anywhere from 1905 to 1913. The equipment on the bench is usually described as their apparatus for counting alpha particles, the work the pair began in 1908 to count each particle automatically as an electrical pulse, instead of spending hours in a dark room watching for faint flashes. That counting work led on to the scattering experiments that brought Rutherford to the atomic nucleus.