Geoffrey Chaucer is best known as the author of The Canterbury Tales, one of the most important works of early English literature. I guess that didn’t pay the bills, because he also wrote one of the first English technical manuals.
Chaucer wrote A Treatise on the Astrolabe in about 1391. He wrote it as if for a child – and possibly it was specifically for a ten year old named Lewis (a family friend).
The text sets out a systematic and clear description of the astrolabe, its workings, and general notes on astronomy and astrology. It was written, like much of Chaucer’s work, in English, although modern speakers may have difficulty deciphering the Middle English of the time:
This tretis, divided in fyve partis, wole I shewe thee under ful lighte rewles and naked wordes in English; for Latin ne canstow yit but smal, my lyte sone.