pilot boring การใช้

• The pilots bore down on the throttles and headed for the open sea.
• To establish a greater understanding, a horizontal pilot boring was undertaken along the line of the service and main tunnels.
• A contract was made with John Waddell & Sons of Edinburgh who appointed James Brunlees and Charles Douglas Fox, eldest son of Sir Charles Fox, as engineers in chief . and as a result construction began in August 1881 before the pilot bore had been completed.