The storage coefficient for a confined aquifer in lower Cambrian sandstone has been calculated, partly from pumping tests and partly from correlations of water-level fluctuations with changes in atmospheric pressure. The different methods of calculation were in close agreement, although the values differed slightly depending on drawdown or recovery and on the horizontal distance to the border of the confining bed. In the pumping tests, the aquifer was undergoing conversion from confined to unconfined condition, which made it possible to calculate the specific yield of the sandstone too.