Sir David Brewster (1781-1868) was a distinguished scientist and inventor who frequently turned the results of his research to practical ends; his work on the diffraction of light, for example, led to his developing improved reflectors for lighthouses and inventing two popular Victorian toys, the stereoscope and the kaleidoscope. He was also active as the editor of the Edinburgh Magazine and the Edinburgh Encyclopaedia (1808-1830) and contributed...