A Popular History of Astronomy during the Nineteenth Century was thought to be Agnes Mary Clerke's greatest work. It covers developments made in the field of astronomy during the nineteenth century and is still used by scholars today who study the history of astrophysics. The book details the career of William Herschel, covers the discovery and development of spectral analysis and progress made on the understanding on sun spots. Margaret Lindsay Huggins, who wrote Clerke's biography, said of the work, "it deserves to live, and it most assuredly will live." (Summary by MillionMoments)