TAILIEUCHUNG - An Encyclopedia of the History of Technology part 10

An Encyclopedia of the History of Technology part 10. This one of a kind encyclopedia presents the entire field of technology from rudimentary agricultural tools to communication satellites in this first of its kind reference source. Following an introduction that discusses basic tools, devices, and mechanisms, the chapters are grouped into five parts that provide detailed information on materials, power and engineering, transportation, communication and calculation, and technology and society, revealing how different technologies have together evolved to produce enormous changes in the course of history | PART ONE MATERIALS Roman lead and silver Roman municipal life was characterized by a prodigal use of water for the supply of which very impressive aqueducts were constructed and lead piping was extensively used for local distribution and plumbing. Some of the lead piping from the ruins of Pompeii which was submerged by volcanic ash in AD 79 has recently been examined in considerable metallurgical detail. These pipes varied in outside diameter from 30 to 40mm and had a wall thickness of 5mm. The method used to produce the pipes was a model of simplicity. Lead sheets 6mm thick were cast on a flat stone surface cut to size and then wrapped around an iron mandrel in such a way that a narrow longitudinal gap was left along the pipe. Into this gap molten lead was poured at such a temperature that it was able to remelt the edges of the cast sheet before solidification. The pipes were then hammered on the mandrel over the whole of their cast surface to reduce their thickness to 5mm and to increase their diameter so that they could be withdrawn. These Pompeian lead pipes contained about per cent copper and per cent of zinc. The mineral wealth of Britain provided much incentive for the Claudian invasion. Tacitus for example remarked that Britain produces gold silver and other metals which are the reward of victory and although the British output of gold was disappointingly low substantial quantities of silver were soon obtained by the cupellation of lead. The Romans were working lead mines in the Mendips six years after the conquest in AD 49. After the silver had been extracted the lead was run into pigs weighing 77-86kg 170-190lb which were exported to the Continent from the port of Clausentum in Southampton Water. The lead from Derbyshire and more northern districts contained very little silver and the lead mines of Mendip Devonshire and Cornwall although significantly richer were still unable to compete with the argentiferous chalcopyrite deposits of Rio Tinto. .

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