Measuring the Monument: fibre optic sensor systems show why Hooke’s and Wren’s plans for a giant telescope within the Monument in London failed

Fibre optic sensor systems have often been used for structural health monitoring applications, usually on bridges, in tunnels and sewers and in various infrastructure where installation is usually only affected by access. This work has tackled a problem of structural monitoring on one of London’s iconic historic buildings, where installation of the chosen fibre optic sensors had to be very carefully planned and agreed with the building owners who imposed severe limits to avoid creating any damage to the structure. Given these restrictions, a fibre optic sensor system was designed and installed to enable the accurate determination of the structural parameters of the building, solving a 350-year-old question of why the building was not able to be used for its original subsidiary purpose, from its design by Robert Hooke and Christopher Wren, as a telescope. Results of on-going research and analysis are reported.