In the summer of 1645, the Oratorian Virgilio Spada (1596–1662) acquired a painting of a debate on astronomy by the Sienese artist Niccolò Tornioli (1598?–1651) and displayed it in the Palazzo Spada, the Roman residence of his older brother, Cardinal Bernardino Spada (1594–1661). Our discussion of The Astronomers questions some of the traditional identifications of its characters, although we cannot claim to have solved these figures’ identities and several remain a mystery. We do present new iconographic interpretations of particular scientific instruments, diagrams, and natural phenomena in the canvas. These novel readings occasionally remain conjectural in part because Tornioli represents these entities in a way that makes it clear that he did not fully comprehend them. The errors and obscurities in Tornioli’s painting lead us to two conclusions. First, that the erudite Virgilio Spada was unlikely to have been involved in the definition of the painting’s iconographies, as he would have objected to Tornioli’s crass mistakes and obscure imagery. Second, that these errors and indistinct details should be taken at face value, insofar as they accentuate the difficulties of astronomical observation. Beyond highlighting these challenges, we argue that the painting also visualizes techniques for countering them. Specifically, the canvas would have focused early modern observers’ attention on the edifying powers of civil conversations and communal observations with scientific instruments as well as images—including diagrams, celestial maps, and paintings.

Time of Our Lives

Sundials of the Adler Planetarium

Sara J. Schechner

Published by the Adler Planetarium, with the support of the North American Sundial Society

The Adler Planetarium of Chicago has the best and most comprehensive collection of sundials and time-finding instruments in North America. Now many of these objects can be yours to explore. This volume encompasses a dazzling array of sundials, 268 in all, that date from the 15th to 20th centuries.

What makes this catalogue special is that it is written to engage non-specialists approaching sundials for the first time. Although the organizational logic is astronomical and mathematical, the primary Interpretive essays set the sundials into cultural and social context.

The catalogue divides sundials into classes according to the element of the Sun’s apparent motion that they track (e.g. hour-angle, altitude, azimuth, or a combination) and the orientation of the surfaces on which the hour lines are mathematically drawn. Within each chapter, the instruments are organized chronologically and by workshop, thereby giving readers insight into that type’s development over time and differences among makers. Technical object descriptions are supplemented by tables of divisions, gazetteers, saints’ days, weather forecasts, and in the case of polyhedral dials, the dial types, orientations, and hour systems drawn on every face. The tables offer a snapshot of the precision to which the maker aimed and the sundial’s complexity. Color photographs of each sundial show its overall appearance and details.

Chapter introductions go beyond mathematical descriptions of how each type works. Drawing upon research findings presented here for the first time, the essays offer insights into early production techniques, fads and fashions, social hierarchy among users, the impact of church and civil authorities, and the history of the sundial classes.

Throughout the ages, people’s sense of time has been influenced by their culture, politics, religion, labor, society, and geography. This catalogue offers concrete evidence, for every sundial in it embodies the time-related needs and values of its maker and users.

The catalogue includes a taxonomy of compass needles, glossary, bibliography, and index. It is hardcover, 488 pages, 9.75” x 11”.

"The Material Culture of Astronomy in Daily Life: Sundials, Science, and Social Change," Journal for the History of Astronomy 32 (2001): 189-222. Translated into Polish by Darek Oczki, and posted with color illustrations in three parts on the Polish sundial website, http://gnomonika.pl at these addresses:

1. Zegary słoneczne, nauka i przemiany społeczne (cz. 1): http://gnomonika.pl/news.php?id=54
   
2. Zegary słoneczne, nauka i przemiany społeczne (cz. 2): http://gnomonika.pl/news.php?id=59
   
3. Zegary słoneczne, nauka i przemiany społeczne (cz. 3): http://gnomonika.pl/news.php?id=62