Science: Tracing the Thames

Britain's Hydraulic Research Board (concerned with rivers, harbors and beaches) has been using radioactive tracers to keep track of the mud of the Thames. At present, the Port of London Authority keeps a fleet of dredges at work on the channel at an annual cost of nearly $2,000,000, and it suspects that a lot of the mud they dredge is washed back up the river by the rising tides. If it could be sure, the Authority figured, it might train the tides of the Thames to carry more mud out to sea.

Asked for help, Britain's Atomic Energy Research Establishment at Harwell...