THE annual session of the Institution of Naval Architects, was held in the Royal Society of Arts during March 29-31. Lord Stonehaven, the president of the Institution, reviewed the events of the last year in his opening address. Sir Stanley Goodall, Director of Naval Construction for the Admiralty, then read an interesting paper describing H.M.S. Ark Royal, the first ship to be designed exclusively as an aircraft carrier. As it is not the function of this type of ship to fight a gun duel, its armament consists mainly of aeroplanes. The ship carries a few guns capable of both high angle and low angle fire. She has a heavily armoured deck, side-armour adequate against medium guns, and improved underwater protection. 103,000 horse-power on three shafts gave her a speed in trials of 313/4 knots and special attention had been given to rapid manoeuvring. The auxiliary machinery is both electric and hydraulic. Special aircraft fittings include two catapults at the fore end of the flying deck, arresting wires at the after end for aircraft landing on it, hydraulically operated wind screens which fold down flat when necessary and three two-story lifts which take aircraft with their wings folded. Electric welding was used extensively in her construction, and this lessened her weight by 500 tons. In the discussion which followed the paper Sir George Preece, engineer-in-ehief to the Navy, said that owing to the necessity for rapid manoeuvring it was found necessary to have two engineers of the watch, one for general control and one for direct supervision. The large rudder immediately abaft the centre propeller was invaluable when turning at rest. In the last cruise, 1,400 aircraft landings on deck had been made without a scratch. ‘Landing on’ had proved safer than driving a car on an English road.