ABSTRACT
At the time when European societies were embarking on the conquest of the great oceanic routes they had at their disposal technical equipment infinitely superior to what was possessed by the Roman Empire in its declining years. There seem to be three large groups of documents which appear in themselves to be capable of shedding some light on mediaeval technical equipment-namely texts, iconography, and material objects. The information that comes from all these three sources is extremely fragmentary and uncertain. The civilisation is mortal, but it is not yet dead: the archaeologist has a perfect right to say that it has at present no ruins. A skilful research-worker, by scrutinising a piece of equipment, or the remains of it, can reconstitute some extremely useful chronological series, as students of prehistory have so brilliantly demonstrated. Thus it was that when modern methods of harnessing first appeared and found slavery moribund, they were not even capable of completing its downfall.
