By way of countering Sir Garnet Wolseley's invocation of the opinion of the Duke of Wellington on the dangers of invasion, the promoters put it about that the Duke of Wellington in his day had strongly opposed the construction of a railway between Portsmouth and London on the ground that it would dangerously facilitate the movement of a French army upon London. They asserted that one unnamed but very high English military figure had even expressed alarm, at the time of the Universal Exhibition of 1851, that the English Cabinet did not insist on the Queen's retiring to Osborne, her country place on the Isle of Wight, because of the large numbers of foreigners at the Exhibition, including three thousand men of the French National Guard, who were allowed to parade the streets of London in uniform, wearing their side arms. And pro-tunnelers recalled in derisive fashion Lord Palmerston's denunciation of the Suez Canal project as "a madcap scheme which would be the ruin of our Indian Empire, were it possible of construction, and which would spell disaster to those who had the temerity to assert it." Colonel Beaumont, as an engineer and military man, too, wrote an article challenging the validity of General Wolseley's conclusions about the tunnel. Colonel Beaumont maintained that Dover might already be regarded as "a first-class fortress, quite safe from any _coup de main_ from without." Concerning an attack by bodies of infantry or cavalry through the tunnel, he declared, "They cannot come by train; as, irrespective of any suspicions on the part of the booking clerks, special train arrangements would have to be made to carry [them]; they cannot march, as they would be run over by the trains, running, as they would do, at intervals of ten minutes, or oftener, without cessation, day or night." Colonel Beaumont also outlined, in his article, a number of precautionary measures that could be taken to secure the safety of the English end of the tunnel. They included a system of pumping coal smoke instead of compressed air from a ventilating shaft into the tunnel, and also the provision of a system of iron water mains that would connect the sea with the ventilating shaft and make it possible for the officer of the guard, in case of invasion, to flood the tunnel by turning a stopcock. In accordance with these proposed measures, Sir Edward, early in 1882, attempted to forestall further military criticism of the Channel-tunnel scheme by having such a ventilating shaft sunk at the eastern end of Shakespeare Cliff, about a mile from the main shaft, and having a start made on another horizontal gallery bored from the foot of the new shaft in the direction of the main pilot tunnel under the sea. The new gallery was four feet instead of seven feet in diameter—the smaller aperture in itself being an additional measure of protection, Sir Edward explained, in that intruders would find it impossible to walk along the ventilation shaft in an upright