A Brief History Of The Internet Pearl, 8.25pm Looking suitably nerdish and bespectacled, Bob Cringely showcases everyone who is anyone related to the Net. Among the eye-openers are the lowly paid software engineers of India's Silicon Valley in Bangalore who keep the www in good repair while the centre of the world in California sleeps. This brief history is pretty comprehensive, at least for the layman, in charting the development of the system, from how it all started in the bowels of the Pentagon to the day Bill Gates (above) caught on and went to war against Netscape. Great Railway Journeys BBC World, 10.10pm The BBC manages to find seven more great railway journeys in the world on which to send renowned personalities, beginning tonight with veteran climber Sir Chris Bonington (above). With his camera and walking boots, the Scotsman crosses mountains more easily than he is used to, travelling in the comfort of trains from Halifax to Porteau Cove in Nova Scotia, Canada, crossing the prairies and the Rockies and exploring the history and culture of this wild land as he goes. At journey's end he goes kayaking in the Pacific Ocean. Subsequent journeys will be made by comedian Alexei Sayle, author and scholar Henry Louis Gates, and explorer Benedict Allen, among others. Horizon: Magic Bullet BBC World, 8.10pm The BBC's oldest science series, which began reporting scientific breakthroughs in 1964, tells of what could be the greatest discovery of all, the drug that might cure any disease from arthritis to cancer and Aids. The drug, called Antisense, targets diseased cells with its encoded DNA, like a magic bullet.