ПЕРЕВЕСТИ
3. The deep tunnelling came later, in 1890. Tunnelling a tube through miles of clay, and sometimes sand and gravel is no easy task, and it was James Henry Greathead who developed the method which was to make most of London's tube tunnels possible.

London transport's experience with tunnels brought them another record. One of the longest continuous railway tunnels in the world is the 17 1/2 mile tunnel on the Northern line.