This is an addendum to an earlier essay on the Purāṇic cosmograph interpreting it in terms of the principles of stereographic projection: Kloetzli (Hist Relig 25(2): 116–147, 1985). That essay provided an approach to understanding the broad structures of the Purāṇic cosmograph but not the central island of Jambudvīpa or its most important region (varṣa) of Bhārata. This addendum focuses on the works of Ptolemy as a resource for understanding the Purāṇic materials. It reaffirms the broad outlines of earlier conclusions, (...) but by understanding the major concerns of Ptolemy’s Geography, is able to provide a far ranging interpretation of the Purāṇic central island of Jambudvīpa. Viewed in the light of the main features of Ptolemy’s Geography, Jambudvīpa, the central island of the Purāṇic cosmograph, can be seen as a geograph modeled on the principles of Ptolemy’s Geography embedded within a larger cosmograph modeled on the principles of Ptolemy’s Planisphaerium—the earth at the center of the universe. Parallels between the seven Ptolemaic climates and the Purāṇic varṣas, the Nile and the Ganges, and the inhabited world (oikumene) and Bhārata deepen our sense of shared tradition as do representations of Bhārata alternately as Alexandria and Babylon. (shrink)

Ptolemy wrote the Planetary Hypotheses for both astronomers and instrument-makers. Most studies of this text concentrate on its meaning for the former, but there remain many questions surrounding its meaning for the latter.1 This article investigates the purpose of Ptolemy’s Planetary Hypotheses in light of what he says about instrument-making. It takes up the following questions: what kind of instrument does Ptolemy describe? And, could such an instrument have been constructed? I argue that he did not have one specific design (...) in mind, but instead he offered craftsmen options for the content, design, and operational methods. In addition to exhibiting his astronomical models and estimating planetary positions, the... (shrink)

The Science Museum, London, has recently acquired four fragments of a portable sundial with associated calendrical gearing. All the fragments are made of low zinc brass of substantially the same composition. The sundial is of a type known in other examples, some the products of recent archaeological excavations and all dated to the Late Antique or Early Byzantine period. Dating by the place names included in the latitude table, by the style of the heads of the planetary gods used to (...) identify the days of the week, and by the style of the script, all indicate that the instrument dates from the late fifth century of the Christian era or the first half of the sixth.The gearing, of which two arbors survive, carrying four toothed wheels and one ratchet, seems to have resembled that of a calendrical device described by al-Bīrūnī in about AD 1000. Like al-Bīrūnī's device and the geared calendar associated with a Persian astrolabe of AD 1221/2 now in the Museum of the History of Science, Oxford, the Byzantine instrument displayed the shape of the Moon and its age in days. Probably the calendar further resembled its Islamic counterparts in also displaying the positions of Sun and Moon in the Zodiac.The emergence of Byzantine mathematical gearing indicates that the Hellenistic tradition attested by the Antikythera machine continued to be active in the Byzantine period, and suggests that it may have influenced the Islamic tradition. Once again an artefact has shown up the inadequacy of the evidence derived from literary sources. (shrink)