The Severn Tunnel works - building the railway tunnel linking South Gloucestershire to Monmouthshire under the estuary of the River Severn. It was built between 1873 and 1886. 1. View of the present Great Western Railway steam ferry, Monmouthshire bank, low tide. 2. Diver in Great Engine pit preparing to descend into the inundated portion to rectify the machinery, Monmouthshire side. 3. Construction of the tunnel on the Gloucestershire side, showing the system of timbering. 4. Scene at the pumping shaft in Five Mile Four pit, Monmouthshire bank.