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High-speed network that gave Navy edge

30 January 2012 | UK  By Tim Cooper 
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One hundred and sixty five years ago this month, the Royal Navy closed down a unique system of communication.

In an age before telegraph, phone or the Internet semaphore enabled the admiralty in London to communicate with ships in Portsmouth in a matter of minutes.

It is a signalling system using two arms which are moved to different positions to represent letters.

The tower at Portsmouth is one of the few survivors from a system which was in operation from 1822 until January 1847 when it was replaced by the telegraph.