The crucial transition to a third phase of understandings about electricity began in the early decades of the nineteenth century, with discoveries and demonstrations of electromagnetism by Hans Christian Oersted and Michael Faraday in 1820 and 1831 respectively, and the construction of more usable batteries by John Frederic Daniell and Sir William Grove in 1836 and 1839. Electricity's therapeutic potential and medical uses in relation to the body, psychology and psychiatry provided another rich vein of speculation for late eighteenth- and nineteenth-century experimentalists. Electricity is invisible and untouchable; its effects can be made apparent but, as a phenomenon that can be neither seen nor touched, it can only ever be obliquely observed. The emergence of the Gothic genre in literature during the same period as early nineteenth-century sciences meant that, as Martin Willis suggests, magic and occultism 'continued to infect' them, as a way of 'interpreting the complex interplay of the mystical and the scientific'.