In addition to the redoubts, he erected a long, slightly curved breastwork behind the embankment, at such a distance from the latter that it was concealed from the view of the enemy. Without experience in this sort of work himself, he relied on Sturge and Jackson, who were learned in all that pertained to parados, traverses, and so on, and took a great pride in the fortification which the Arabs constructed to their plans, and still more in the fact that, though they had picked up only a word or two of Arabic, they were able to dispense with Burnet's assistance as interpreter after the first day. The Turks, meanwhile, though they refrained from attacking, were not idle. They strengthened their bridgehead half-way along the causeway, fencing the latter on both sides with a mud wall just high enough to cover their movements up and down. The wall was no doubt easily penetrable by rifle or machine-gun bullets, but, as the Turks must have guessed, the garrison's supply of ammunition was not sufficient to allow them to pepper the wall at random on the chance of hitting the men behind it. Burnet hindered their work as much as possible by employing some of the best marksmen among the Arabs as snipers; the vegetation, however, that fringed the causeway formed in itself a very effective screen to the enemy, and he feared that a good proportion of the snipers' bullets were wasted. Remembering the old adage that it is lawful to learn from the enemy, Burnet was inclined to raise similar walls on his own side of the central gap. But he saw on reflection that if the Turks succeeded in bridging the gap--and that was always to be reckoned with--such walls would give them invaluable cover right up to the shore of the island. He therefore abandoned the idea. It was Sturge who suggested the employment of listening patrols by night, to discover any new movement on the part of the enemy. His crude idea was merely to send a few picked men along the causeway as far as the gap. Burnet improved on this. With Rejeb's consent he sent, nightly, a swimmer on an inflated skin from the kelak to worm his way under cover of the reeds as near to the enemy's walls as possible. For three nights the scout's report was of no great value, but on the fourth, just before dawn, he came back with the news that there was considerable movement at the bridgehead and along the causeway, and a good deal of bustle on shore. Not a little surprised that the enemy, after waiting so long for guns, had apparently decided to attack without them, Burnet at once reinforced the small body of picked men on duty at the outwork at his end of the gap, and sent word to the garrisons of the redoubts to be on the alert. The two English gunners were eager to take a part at once, but Burnet, with wise forethought, declined to let them use their guns or even enter the firing-line. The enemy's intentions were not yet disclosed.