Solar and stellar photospheres constitute the layers most accessible to observations, forming the interface between the interior and the outside of the stars. The solar atmosphere is a rich physics laboratory, in which the whole spectrum of radiative, dynamical, and magnetic processes that tranfer energy into space can be observed. As the fundamental processes take place on very small spatial scales, we need high· resolution observations to explore them. On the other hand the small-scale processes act together to form global properties of the sun, which have their origins in the solar interior. The rapid advances in observational techniques and theoreticallllodelling over the past decade made it very timely to bring together scientists from east and west to the first lAU Symposium on this topic. The physics of the photosphere involves complicated interactions between magnetic fields, convection, waves, and radiation. During the past decade our understanding of these gener ally small-scale structures and processes has been dramatically advanced. New instrumen tations, on ground and in space, have given us new means to study the granular convection. Diagnostic methods in Stokes polarimetry have allowed us to go beyond the limitations of spatial resolution to explore the structure and dynamics of the subarcsec magnetic struc tures. Extensive numerical simulations of the interaction between convection and magnetic fields using powerful supercomputers are providing deepened physical insight. Granulation, magnetic fields, and dynamo processes are being explored in the photospheres of other stars, guided by our improved understanding of the solar photosphere.

"Letters to the Editor" issued as Part 2 and separately paged from v. 148, 1967.

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.