The Royal Institution Christmas lectures for young people.
A series of six lectures on the theme of measurement given by Professor R.V. Jones FRS.

During World War II, scientists on both sides were much concerned with the difficult problem posed by accurate navigation. However, as with so many war-time inventions, the consequent improvement in navigational methods were also used to drop bombs precisely and to guide long-range missiles to their distant targets. The subsequent development of early radio and radar guidance systems, today enables intercontinental rockets to be aimed with an accuracy of a few hundred yards from their intended target at a range of 8,000 miles.
(Final part tomorrow)