Not sure what you have in mind with "manuals", but I believe there were treatises on every subject, e.g. Vitruvius' On architecture (~20BC), "a guide for buildi

Not sure what you have in mind with "manuals", but I believe there were treatises on every subject, e.g. Vitruvius' On architecture (~20BC), "a guide for building projects. As the only treatise on architecture to survive from antiquity, it has been regarded since the Renaissance as the first book on architectural theory, as well as a major source on the canon of classical architecture. It contains a variety of information on Greek and Roman buildings, as well as prescriptions for the planning and design of military camps, cities, and structures both large (aqueducts, buildings, baths, harbours) and small (machines, measuring devices, instruments)" https://en.wikipedia.org/wiki/De_architectura https://en.wikipedia.org/wiki/De_architectura Ptolemy (100-170AD) wrote treatises on many subjects, and his works on astronomy and geography "never ceased to be copied or commented upon, both in Late Antiquity and in the Middle Ages" https://en.wikipedia.org/wiki/Ptolemy https://en.wikipedia.org/wiki/Ptolemy Vegetius wrote a military manual On military matters, extremely influential until about 1500. https://en.wikipedia.org/wiki/Vegetius https://en.wikipedia.org/wiki/Vegetius Apicius wrote On the Subject of Cooking, a cook book. https://en.wikipedia.org/wiki/Apicius https://en.wikipedia.org/wiki/Apicius (So much ancient writing hasn't survived, e.g. none of Aristotle's many writings survived - what we know as his writings are just his students' lecture notes.)