Abstract
This article examines a little known, but superb piece of ancient technical writing, in fact the first technical writing in English on a complex scientific instrument: A Treatise on the Astrolabe by the medieval poet, Geoffrey Chaucer. As late as 1932, Chaucer's treatise was still touted by a science historian as unsurpassed among English writings on the astrolabe; yet it has received little attention within the technical writing field. To gain deeper understanding of the strengths and enduring powers of this piece of technical writing, so we can apply these insights to modern efforts, this article examines Chaucer's treatise and also looks briefly at Chaucer's source, an eighth-century work by an Arabian astronomer, Messahala. This examination of historical descriptions and instructions shows that many of our current conventions and forms in handling these modes of writing were both natural and traditional in Chaucer's time, and some even in Messahala's.