Spectropia; or, Surprising Spectral Illusions Showing Ghosts Everywhere, and of Any Colour

"Spectropia; or, Surprising Spectral Illusions" by J. H. Brown is a mid-19th century exploration into the science behind seeing ghosts, unraveling the mystery of optical illusions through light and the human eye—it gives the scientific explanation for paranormal optical mysteries. The book presents a way to make spectral images by staring at drawings and then watching as colorful ghost-like copies appear, explaining how our eyes see colors and trick our brains. Brown explains how alleged historic ghost sightings and the paranormal aren’t supernatural, but just tricks of the eye, and takes aim at the spiritualism and witchcraft ideas popular during the period, teaching the reader that science holds the answers to what seems unreal.