Every hour of the day and night all over the world silent instruments are watching, listening, recording. In cellars the needles of seismographs detect and record the slightest vibration in the earth; at hundreds of meteorological stations thermographs and barographs continuously record information about the weather. In today's programme Philip McAllen shows how these instruments and the people who use them have a strange connection with the backroom planners who organise and control complicated railway systems.
(Recording of Monday's broadcast)
(to 11.45)