The Astrolabe Project

An Early Portuguese Mariner's Astrolabe from the Sodré Wreck‐site, Al Hallaniyah, Oman

“…The development of the mariner's astrolabe is unclear (Anderson, : 3; Castro et al ., ). They were first recorded as being used by the Portuguese Diogo d'Azambuja on a voyage down the west coast of Africa in 1481 (Stimson, : 16).…”

“…The analysis reveals the disc to be made of leaded gunmetal with the following major elements: copper (66.43%), zinc (7.82%), tin (5.34%) and lead (2.78%). Castro has suggested that knowing the alloy composition of mariner's astrolabes could be used, along with other characteristics, to guess their geographic origin (Castro et al ., : 232). Metallurgical analysis (EDX) has also been performed on the Champlain or Cobden astrolabe (NMM‐8; CMAC‐8, see Fig.…”

“…The mantle of maintaining the inventory of known astrolabes has since been taken up by a team led by Professor Filipe Castro from the J. Richard Steffy Ship Reconstruction Laboratory (ShipLAB) at the Center for Maritime Archaeology and Conservation (CMAC) of Texas A&M University. Continuing Stimson's list and incorporating the results of an earlier student thesis (Garcia, ), the CMAC team published their first catalogue at the end of 2015, which included 40 new specimens (Castro et al ., ). The CMAC catalogue has since been updated twice and the total number of specimens currently stands at 109; comprised of 105 astrolabes and four alidades (Fig.…”

“…The significant increase in astrolabe numbers from the time of Stimson's study also provided CMAC with an opportunity to conduct a major review of all known specimens with regards to taxonomy and chronology (Castro et al ., ). In addition to compiling the history, situation, condition, and characteristics of these astrolabes in a single publication, CMAC have established a multitude of new sub‐types to reflect the variety of forms seen mainly in wheel‐type astrolabes with base ballasts.…”

“…In addition to compiling the history, situation, condition, and characteristics of these astrolabes in a single publication, CMAC have established a multitude of new sub‐types to reflect the variety of forms seen mainly in wheel‐type astrolabes with base ballasts. While a stated objective is to use the taxonomy and chronology of an astrolabe to help date and identify the shipwreck from which it was recovered, the authors concede that the current sample size is still too small for such determinations (Castro et al ., : 231). In some cases, however, an astrolabe from a reliably dated shipwreck can fill a gap, or help to bolster the taxonomic and chronologic record.…”