Reviews Astronomical Spectrographs and their History by John Hearnshaw Share this:EmailFacebookTwitterPinterestPocketRedditPrint By Science News May 8, 2009 at 1:53 pm Astronomers have used these instruments to explore the heavens since the 19th century. Cambridge Univ., 2009, 240 p., $140. ASTRONOMICAL SPECTROGRAPHS AND THEIR HISTORY BY JOHN HEARNSHAW