Postcard from G F Fg [George Francis Fitzgerald], T C D [Trinity College, Dublin], to Joseph Larmor, St John's College, Cambridge Fitzgerald has been trying for years to bring out the electromagnetic interpretation of [Hermann von] Helmholtz and the host of dispersion theorists. Resonance theories are the only possible ones. Fitzgerald believes in electrons; he thinks that Helmholtz 'invented equations to get the results'. In a postscript, he states that he tried the mercury experiment again, with the same result. 25 March 1895