On the 28th of May the enemy sent in a flag of truce. Before the object of it was known, the governor remarked to the officers near him that he supposed the duke had arrived, and had sent to summon the garrison to surrender. His reply, he said, would be brief, “No--no;” and he hoped his officers would support him. The summons, however, was not made, and the laconic answer, therefore, was not given. But it is due to the Duke of Crillon to record his courtesy. He wrote to General Elliot to acquaint him with the arrival of the French prince, and in their name to express their high estimation of his courage and character. The letter was accompanied by a present of fresh fruits and vegetables, with ice, game, and other luxuries for the use of his staff. He knew, said the duke, that the governor lived wholly upon vegetables, and if informed of the description he preferred, he would furnish a daily supply. The governor replied in suitable terms; but while accepting the Spanish commander’s gifts, begged of him to send no more, as he made it a point of honour to share with the meanest of his fellow-soldiers both want and plenty. In planning a combined attack by land and sea upon the Rock, the besiegers felt it was necessary to guard against the destruction of the naval force by the batteries of the fortress before it could get near enough to render any service. But how was the fire of the English guns to be silenced? It occurred to M. d’Arçon that what was wanted was a number of fireproof batteries, which could take up and maintain a position in the Bay, regardless of the cannonade delivered against them by the garrison. In the construction of these floating castles M. d’Arçon exhausted all his ingenuity. There were ten of them, each armed with fifteen heavy guns, and their structure was as follows:--On the larboard side they were six or seven feet thick, made of green timber, bolted and cased with cork, iron, and raw hides. Inside they were lined with a bed of wet sand, and in case they should nevertheless take fire, currents of water were poured through them by a system of pumps and channels, so that, should any red-hot shot pierce the vessel and open up any one of the ducts, the water would pour forth instantly and extinguish the flames. As an additional protection, each tower was covered with a slanting bomb-proof roof, capable of being raised or lowered at pleasure, by means of machinery, from which, it was calculated, the balls would glide harmlessly into the sea. In fact, the devices for the protection of the besiegers seem to have been more numerous and more skilful than those for the attack of the besieged. We must add that these ponderous floating batteries were masted and rigged, so as to sail like frigates.