Mr. Peter Mason (Member of Council), opening the discussion, said that he personally found the whole subject of immersed tube tunnels an extremely fascinating one. He was an engineer with a foot in both camps, both civil and structural. As a civil engineer he was very interested in tunnelling, but for the normal bored tunnel the part the structural engineer had to play was not quite so prominent as that of the mining and civil engineer. However, with the type of submerged tunnel that they had just been hearing about the structural engineer came into his own because the design of the tunnel sections was a completely structural problem.