source: The second tube was in lifted into place 7 January 1850, a single line was open to public traffic through these tubes 18 March 1850, and the second line was open 19 October.
target: The second tube was in lifted into place 7 January 1850. A single line was open to public traffic through these tubes 18 March 1850. The second line was open 19 October.
references: The second tube was in lifted into place 7 January 1850. A single line was open to public traffic through these tubes 18 March 1850. The second line was open 19 October.