"It appears that Mr Peto the contractor, for the accommodation of those parties whose property lies above the line of the old Tunnel...agreed to strengthen it by building a certain number of cross walls at short intervals...The mode adopted in doing it was to drive a small gallery laterally from the side of the new Tunnel to reach the old one at a point some distance beyond the 20 feet which had been solidly built up. Through this gallery the materials were introduced and 3, 4 or more cross walls about 10 feet apart were built within it...