The Chief Engineer of Anglo-Iranian, Clifford Hartley, was visiting the Petroleum Warfare Department at this time, and he heard about the proposal, and was convinced that it was possible.[8] In the hilly terrain of Iran, Anglo-Iranian had employed a 3-inch (7.6 cm) pipeline. Running at 1,500 psi (10,000 kPa), it delivered 100,000 imperial gallons (450,000 l) per day, the equivalent of over 20,000 jerricans. On 15 April he pitched his proposal for a continuous length of pipeline similar to a submarine communications cable without the core and insulation, but with armour to withstand the internal pressure, which could be deployed by a cable-layer ship.