Beijing Institute Of Technology
The primary sewer in Rome was the Cloaca Maxima; construction began on it in the sixth century BCE and it is still in use today. Hominids started using primitive stone tools millions of years ago. The earliest stone tools were little more than a fractured rock, but approximately 75,000 years ago, pressure flaking provided a way to make much finer work. This article is about the use and knowledge of techniques and processes for producing goods and services. Continuing improvements led to the furnace and bellows and provided, for the first time, the ability to smelt and forge gold, copper, silver, and lead – native metals found in relatively pure form in nature. The advantages of copper tools over stone, bone, and wooden tools were quickly apparent to early humans, and native copper was probably used from near the beginning of Neolithic times . Native copper does not naturally occur in large amounts, but copper ores are quite common and some of them produce metal easily when burned in