Title page to Herschel's 'A treatise on astronomy', 1851.
© Science Museum / Science & Society Picture Library
Engraved vignette showing a Renaissance astronomer, possibly Galileo (1564-1642), observing the Moon through a telescope. Title page to Sir John Herschel's (1792-1871) work, 'A treatise on astronomy' published in London in 1851. Son of famous astronomer Sir William Herschel (1738-1822), John Herschel continued his father's work by mapping the sky of the southern hemisphere. He discovered thousands of new celestial objects whose position he carefully plotted. He also discovered 525 nebulae and clusters, pioneered celestial photography, discovering the cyanotype or blueprint process in 1842, carried out research on photo-active chemicals and the wave theory of light and coined the photographic terms 'negative and 'positive'.