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. (shrink)