Thyne Oldest Known Tech Manual

johnshirley writes "How old is the oldest known technical manual? About 613 years, it seems. Written in 1391 by Geoffrey Chaucer for his ten year old son Lewis (Lowys), the manual explains in great detail but very rough spelling and grammar, the intricate workings of the Astrolabe--the predecessor to the sextant. Read Chaucer's 'A Treatise on the Astrolabe here."