Artesian well: Artesian well, well from which water flows under natural pressure without pumping. It is dug or drilled wherever a gently dipping, permeable rock layer (such as sandstone)
It is known to be the worst air-pollution event in the history of the United Kingdom, and the most significant in terms of its effect on environmental research, government regulation, and public awareness of the relationship between air quality and health. Bell, Michelle L. and Davis, Devra Lee. 2  Reassessment of the Lethal London Fog of 1952: Novel Indicators of Acute and Chronic Consequences of Acute Exposure to Air Pollution ( Environmental Health Perspectives , June 2001).
By 1932, the first tubes made from a PVC copolymer were produced. Nearly three years later the first PVC pipes were produced using a roll mill and hydraulic extruder. This two step process involved melting the PVC powder on a roll mill and rolling the sheet produced up to a billet. The PVC could then be processed in a discontinuously working ram extruder to make pipe.