Book Reviews 491 of Christianity in the late Roman Empire. This will be one of several points where a teacher will want to provide much needed context and better informed historical argu- ments. Because the story basically ends at Newtonian mechanics, the book does not cover enough material for one-semester introductory astronomy courses as they are commonly taught. The graphics, while serviceable, are sometimes crowded and would be consider- ably clarified in many cases by redrafting to cover a full page. However, typographical errors are relatively few for a first edition. The book includes a full index, but a glossary would be a valuable addition. JAMES M. LATTIS Department of Astronomy, University of Wisconsin - Madison, USA lattis@astro.wisc.edu Early Portable Watches Zeit haben – Tragbare Uhren vor 1550. Dietrich Matthes (Carpe Diem Publishing, Dover, DE, 2018). Pp. 499. €99. ISBN 9780692979457. This large and amply illustrated book provides a list and classification of all currently known “portable watches” up to 1550. Portability means the possibility of wearing clocks on the owner’s garment or body. Matthes sorts the watches into three categories by shape: pomander watches, drum-shaped watches, and flat watches worn around the neck (Bisamapfeluhren, Dosenuhren, Halsuhren). The first two chapters of this weighty book provide general background on the devel- opment of miniature horological mechanisms, including larger table clocks and other spring-driven clocks (Tischuhren, Kutschenuhren). Archival sources and glimpses of contemporaneous iconography suggest that this development arose from exchanges of technology and luxury fashion among France, Italy, and Germany and other regional centres. The following three chapters are dedicated to the three categories of watches, with the longest on the drum-shaped watches, covering 50 pages. It further divides this set into sub-categories (group HS – Henlein Steinmeissel, group C and M – according to a pounced “C” and “M,” group Z – Zech), based on either identified workshops or char- acteristics of the mechanical realization. Matthes has chosen not to explore why the wealthy, in Europe as in the Near East, began wearing watches. Instead, he offers his survey and categories as a prerequisite for a better understanding of the social roles of these objects. Nevertheless, the passing of time certainly was one of the aspects that captivated the imagination of early watch own- ers. Chapter 6 treats the various indications of hours, minutes, and even seconds and astronomical information on the watches (the chronological scope is expanded here to the end of the sixteenth century). This chapter contains a short digression on the use of spring-driven clocks in astronomy, sometimes with a seconds hand (mentioned in Fabricius’ Encomion sanitatis, 1557; in the 1586 observation records in Kassel under the