London's only lighthouse — at Trinity Buoy Wharf near Canning Town — will emit a beam, for the first time since it closed for duty in the late 19th century.
Sonic Ray is an installation by Artangel that'll project a beam from the lighthouse, across the river to North Greenwich and Richard Wilson's cleaved ship sculpture, Slice of Reality.
The beam of light — which will appear from dusk Wednesdays till Sundays, from 30 September till 21 November — will in fact encode and transmit the sound of Longplayer, Jem Finer's 1,000 year-long musical composition, which has been playing in Trinity Buoy Wharf Lighthouse since midday on 31 December 1999. Slice of Reality will then be used as a 'listening' post for the composition.
A short ferry ride will connect the lighthouse and the listening post, inviting people to experience Longplayer as a 'bridge of light' between the two landmarks.
Sonic Ray, until 21 November, tickets (including ferry ride) £7.50/£5 concessions
Pedant's note: you might argue — as indeed we previously have — that Trinity Buoy Wharf's is not London's only lighthouse. Depends on how you stretch the definition really.