Thames Tunnel

Hand-coloured. Marc Brunel's Thames Tunnel between Rotherhithe and Wapping was the first underwater tunnel in the world. Several attempts to construct a tunnel under the Thames had failed by the time Brunel patented a tunnelling shield in 1818. Five years later Parliament authorised his plan to use the shield. It worked by exposing only a small proportion of the excavation face, thus reducing (although not eliminating) the chances of the tunnel collapsing. Opened in 1843, the tunnel was used solely for foot passengers until the 1860s, when it was converted to carry the East London Railway. It still carries trains of the East London Line, now part of the London Underground.

Thames Tunnel (Plan and elevation of the Rotherhithe Tunnel - engineer Isambard Marc Brunel -annotated in ink) Opened 25 march 1843

© National Maritime Museum Collections

The Codebreakers: The Comprehensive History of Secret Communication from ... - David Kahn - Google Books

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From: https://books.google.co.uk/books?id=3S8rhOEmDIIC

"These men received their foreign interceptions from the Secret Office and their

domestic ones from the Private Office, both subdivisions of the Post Office. The Secret

Office was quartered in three rooms adjoining the Foreign Office and entered privately

from Abchurch Lane. Fire and candles burned constantly in one room; the staff lodged

in the others. It included men who made their life's work the specialty of unsealing

diplomatic packets with such deftness that they could be resealed without evidence of

tampering; one such opener was J. E. Bode, father of John Bode, Jr. He regularly spent

three hours on the dispatches of the King of Prussia, opening them and then resealing

them with special wax and carefully counterfeited seals. Perhaps surprisingly in a

bastion of human rights, its interceptions enjoyed full legality. The statute of 1657 that

established the postal service declared outright that the mails were the best means of

discovering dangerous and wicked designs against the commonwealth. Leases of 1660

and 1663, confirmed by the Post Office Act of 1711, permitted government officials to

open mail under warrants that they themselves issued. They sidestepped this

bothersome procedure by promul gating all-inclusive general warrants." The Secret

Office sent interceptions en clair to the king and those in cipher to the cryptanalysts."