The Astrolabe Craftsmen of Lahore and Early Brass Metallurgy

Summary

A study of the metallurgy and manufacturing techniques of a group of eight astrolabes (seven from Lahore, one attributed to India) using non-destructive methods has produced the earliest evidence for systematic use of high-zinc (α + β) brass. To produce this alloy, the brass industry supplying the Lahore instrument makers must have co-melted metallic copper and zinc. This brass-making technology was previously believed to have been developed on an industrial scale in the nineteenth century in Europe. This work hypothesizes that this technology was used in Lahore on an industrial scale as early as ad 1601. In addition, this work hypothesizes that the α + β brass alloy was used specifically for its ease in manufacturing the thin sheet brass required for astrolabe-component manufacture.

Acknowledgments

The authors would like to thank the Adler Planetarium and Astronomy Museum of Chicago, IL for access to the astrolabes studied in this work. Dr Newbury was supported by the Department of Energy Office of Science, Office of Basic Energy Sciences, under contract # W-31-109-Eng-38 as well as by the Adler Planetarium and Astronomy Museum for travel funds.

Notes

¹R.B. Gordon, ‘Sixteenth-Century Metalworking Technology Use in the Manufacture of Two German Astrolabes’, Annals of Science, 44 (1987), 71–84.

R.B. Gordon, ‘Metallography of Brass in a Sixteenth Century Astrolabe’. Historical Metallurgy, 20 (1986), 93–96.

²For a more thorough introduction and explanation of synchrotrons, please visit the home page of the Advanced Photon Source synchrotron at www.aps.anl.gov.

³G.B. Stephenson, B. Stephenson, and D.R. Haeffner, ‘Investigations of Astrolabe Metallurgy Using Synchrotron Radiation’, MRS Bulletin, 26 (2001), 19–23.

⁴On the Lahore instrument makers see S.R. Sarma, ‘The Lahore family of astrolabists and their ouvrage,’ Studies in History of Medicine and Science 13 (1994), 203–24; E. Savage-Smith, Islamicate Celestial Globes (Washington, 1985), 34–44 et passim.

⁵A.J. Turner, The Time Museum Volume 1, Time Measuring Instruments: Part 1 Astrolabes and Astrolabe Related Instruments (Rockford, IL, 1985), 74–83.

⁶Lahore workshops continued to produce astrolabes into the nineteenth century. None of these later Lahore astrolabes, however, are in the Adler collection.

⁷R.T. Gunther, The Astrolabes of the World, 2 vols (Oxford, 1932), I.

S.R. Sarma, 205–24.

⁸E. Savage-Smith, p. 93.

⁹On these globes, see Savage-Smith (1984). Although it is perfectly possible to fashion metal globes by combining two individually shaped hemispheres, the Lahore craftsmen preferred to make so-called ‘seamless’ globes using the demanding lost-wax (cire perdue) method, well described by Savage-Smith, which yields a more truly spherical shape at the cost of a great deal of tedious labour.

¹⁰P.T. Craddock, I.C. Freestone, L.K. Gurjar, A.P. Middleton, and L. Willies, ‘Zinc in India’, in 2000 Years of Zinc and Brass Revised Edition, edited by P.T. Craddock, (London, 1998), 27–72.

¹¹W. Zhou, ‘Chinese Traditional Zinc Smelting Technology and the History of Zinc Production in China’. Bulletin of the Metals Museum, 25 (1996), 36–47.

¹²For a complete description of phase diagrams, please see ASM Handbook Volume 3: Alloy Phase Diagrams, edited by H. Baker (Materials Park, OH, 1992), Section 2, 182.

¹³These composition ranges are approximate, since the phase boundary changes with temperature as seen in figure 2. For an in-depth discussion of the temperature dependence on the phase boundaries of the α and α + β phase fields, please see pp. 146, 164–65 of Brian Dale Newbury, ‘A non-destructive synchrotron X-ray study of the metallurgy and manufacturing processes of Eastern and Western astrolabes in the Adler Planetarium collection’ (doctoral dissertation, Lehigh University, 2005).

¹⁴J. Bayley, ‘Roman Brass-Making in Britain’, Historical Metallurgy, 18 (1984), 42–43.A.M. Pollard and C. Heron, Archaeological Chemistry (Cambridge, 1996), 196–238.

¹⁵K. Haedecke, ‘Equilibria in the Production of Brass by the Calamine Process’, Erzmetall, 26 (1973), 229. P.T. Craddock, Early Metal Mining and Production (Edinburgh, 1995), 292–302. Joseph B. Lambert, Traces of the Past: Unraveling the Secrets of Archaeology Through Chemistry (Reading, MA, 1997), 192–93. R.F. Tylecote, A History of Metallurgy (London, 1976), 96.

¹⁶J. Bayley, 42–43.

¹⁷Joan Day, ‘Brass and Zinc in Europe from the Middle Ages Until the Mid-Nineteenth Century’, in 2000 Years of Zinc and Brass Revised Edition, edited by P.T. Craddock, (London, 1998), 147.

¹⁸P.T. Craddock, S.C. La Niece, and D. Hook, ‘Brass in the Medieval Islamic World’, in 2000 Years of Zinc and Brass Revised Edition, edited by P.T. Craddock (London, 1998), 73–114.

¹⁹M. Martinon-Torres and T. Rehren, ‘Agricola and Zwickau: Theory and Practice of Renaissance Brass Production in SE Germany’, Historical Metallurgy, 36 (2002), 95–111.

²⁰K. Haedecke, 229–33.

²¹A.M. Pollard and C. Heron, 196–234.

P.T. Craddock, S.C. La Niece, and D. Hook, 73–114.

²²Brian Dale Newbury, 102–45.

²³B. Newbury, B. Stephenson, J. Almer, M. Notis, G.S. Cargill, III, G.B. Stephenson, and D. Haeffner, ‘Synchrotron Applications in Archaeometallurgy: Analysis of High Zinc Brass Astrolabes’, Powder Diffraction, 19 (2004), 12–15.

²⁴The difference between ? and ?′ is immaterial to the scope of this work, but for a further discussion see Brian Dale Newbury, 146–255.

²⁵J. Lang, ‘Chapter 2 Metals’, in Radiography of Cultural Material, edited by J. Lang and A. Middleton (Oxford, 1997), 41.

²⁶Sandra K. Zacharias, ‘Brass Making in Medieval Western Europe’, in All That Glitters: Readings in Historical Metallurgy, edited by Michael L. Wayman (Montreal, 1989), 37.

A. Sisco and C.S. Smith, Lazarus Ercker's Treatise on Ores and Assaying (Chicago, 1951), 258.

²⁷J.H. Mendenhall, Understanding Copper Alloys (New York, 1977), 42.

²⁸D.K. Allen, Metallurgy Theory and Practice (Chicago, 1969), 430–40.

²⁹J.H. Mendenhall, p. 12.

³⁰A.Y. Al-Hassan and D.R. Hill. Islamic Technology: an Illustrated History (Cambridge, 1986), 249–50.

³¹D.K. Allen, p. 438.

³²B. Newbury, M. Notis, and D. Newbury, ‘Revisiting the zinc composition limit of the cementation process of brass manufacture’, Historical Metallurgy, in press.

³³P.T. Craddock, I.C. Freestone, L.K. Gurjar, A.P. Middleton, and L. Willies, 27–72.

³⁴A.K. Biswas, Minerals and Metals in Pre-Modern India (New Delhi, 2001), 141–85.