11.45 Geophysical Techniques
For many years it was believed that the basement rocks under Wensleydale were granites. This programme shows how scientists mapped the rocks and eventually succeeded in proving that they were indeed granite.
12.10Modulation
How can you have lots of radio signals in a single aerial and be able to ' tune In ' to the one you want? It's by using modulation, and different types are available for use in special circumstances.