Think of a NumberSeries 1Episode 4: WaterBBC One Duration: 25 minutesFirst broadcast: Wed 3rd May 1978, 17:15 on BBC One WestLatest broadcast: Wed 18th Apr 1979, 16:35 on BBC One WalesIn this edition, the theme is water. Johnny Ball considers icebergs, soap bubbles, model divers and John Lethbridge's early diving bell.GenresChildren'sFactualBrandThink of a NumberSeriesThink of a Number: Series 1 Source: BBC Online