John Davis obtained his PhD from Cambridge University in 1982 for work on electron beam processing of semiconductors. Since his retirement from telecommunications research in 2000 he has researched early scientific instruments, particularly sundials and astrolabes, with a particular interest in their metallurgy.Anthony Turner is an independent scholar and freelance consultant. His main areas of interest are the social history of ideas during the Ancien Régime, the history of scientific instruments, clocks, watches and sundials, and of precision technology in general. Consultant to Sotheby's and to Bonhams on scientific instruments, he also acts as expert to Paris auctioneers for horology and science sales held in their rooms in the rue Drouot. In 2018 he was awarded the Paul Bunge prize for contributions to the history of scientific instruments, and in 2021, the Gaia Prize for his work on the history of horology.

• Introduction: what is an astrolabe? 1: Astrolabes and Quadrants in England, 1000-1300 2: Making the Instruments 3: Methods of Analysis and dating 4: The Instruments Described 5: Interpreting the Data 6: English Styles of Astrolabe Design and their Influence in Mainland Europe Appendix 1: The early Latin astrolabe (IIL 161) in the British Museum Appendix 2: Saint's days on the astrolabes described Appendix 3: Stars on the instruments described Appendix 4: XRF results from Medieval European astrolabes Appendix 5: Luni-solar data on the astrolabes Appendix 6: Spacing of the azimuth curves and almucantars on the instruments described arranged by date Appendix 7: Altitude sundials on astrolabe alidades Appendix 8: Concordance of instrument numbers with International Instrument List numbers