Originally published in 1958 and following an increasing interest in electromagnetic phenomena in the decade preceding this symposium, this book contains the presented papers from symposium number 6, organised by the International Astronomical Union and held on 27th–28th and 30th–31st August 1956 at the Royal Institute of Technology in Stockholm and on 29th August at the Stockholm Observatory in Saltsjöbaden. 'The discussions were confined to such questions as could be investigated by theory, experiments and observations'. Papers are wide-ranging and include 'Stellar magnetism', 'Solar and interplanetary magnetic fields' and 'Electromagnetic state in interplanetary space'. Notably, 'final conclusions were not reached, but the discussions clearly showed the many changing aspects of magneto-hydrodynamics' and 'new aspects were presented on the origin and structure of sunspots'. Multiple photographs are included for reference. This vibrant, engaging and historical book will be of significant value to anyone with an interest in cosmical physics.