I HAVE analysed bittern and carnallite of industrial origin and deduced the concentration of cæsium-137 in the coastal waters in early 1958 of Japan as 70–150 µµc. kgm./l. 1 Recently, by ...

This provides a signal of roughly the correct value which excites the cesium beam tube. The tube’s output is used in a phase-locked loop to discipline the 5 MHz clock to be right on. This works ...

Accurate timekeeping has always been part of humankind’s social evolution. At the Neolithic monument of Newgrange in Ireland, a special opening above an entrance allows sunlight to illuminate the ...