Pair of sound mirrors

The mirrors are at either end of the bridge just to the left of each end.

A modern acoustic mirror has been built (in 2003?) on the bank of the Royal Military canal close to the Hythe mirrors.

There is a listening mirror on the north (far) bank of the canal, and a speaking point on the south (near) side. The idea is that you can use the mirror to talk to someone on the opposite bank.