Book excerpt: Ever since the boom of spectrum analysis in the 1860s, spectroscopy has become one of the most fruitful research technologies in analytic chemistry, physics, astronomy, and other sciences. This book is the first in-depth study of the ways in which various types of spectra, especially the sun's Fraunhofer lines, have been recorded, displayed, and interpreted. The book assesses the virtues and pitfalls of various types of depictions, including hand sketches, woodcuts, engravings, lithographs and, from the late 1870s onwards, photomechanical reproductions. The material of a 19th-century engraver or lithographer, the daily research practice of a spectroscopist in the laboratory, or a student's use of spectrum posters in the classroom, all are looked at and documented here. For pioneers of photography such as John Herschel or Hermann Wilhelm Vogel, the spectrum even served as a prime test object for gauging the color sensitivity of their processes. This is a broad, contextual portrayal of the visual culture of spectroscopy in the 19th and early 20th centuries. The illustrations are not confined to spectra--they show instruments, laboratories, people at work, and plates of printing manuals. The result is a multifacetted description, focusing on the period from Fraunhofer up to the beginning of Bohr's quantum theory. A great deal of new and fascinating material from two dozen archives has been included. A must for anyone interested in the history of modern science or in research practice using visual representations.