Oil on canvas, painting of the Solar Spectrum / C M Simpson, 4'6 1/4"x4 3/8". In preparing this representation of the visible portion of the Solar Spectrum, Miss Simpson used the solar spectroscope at the Observatory of William Alfred Parr (1865-1936), FRAS at St Albans. The colours are rendered as faithfully as possible, and the position of the Fraunhofer absorption lines are indicated. Parr used a 4-inch Cooke equatorial to which was attached a 2-prism Evershed spectroscope made for him by Adam Hilger, Ltd in his Observatory, 1926-1936.