Slowly the day wore on. At frequent intervals Denbigh climbed the hillock and brought his glasses to bear upon the distant high ground. Once or twice he fancied he heard the sounds of musketry and Maxim firing in the sultry air. Armstrong and several of the men were of the same opinion, agreeing that the firing was desultory and not constantly maintained. At length darkness fell. No one had seen the sea-planes returning before sunset, and in addition to the great risk of making a night landing these craft are of little practical use except in daylight. With the approach of night Denbigh ordered double sentries to be posted, and cautioned the boat-keepers to be alert and watchful for signals. Those of the men left behind slept or rested beside the quick-firers, protected from the heavy dew by boat awnings stretched on oars and boat-hooks. For Denbigh sleep was out of the question. Muffled in a boat-cloak, for the off-shore wind blew chilly, he paced up and down with the mate of the _Myra_. "What's that over yonder?" asked Armstrong. "Flashes--musketry," replied Denbigh. "It's strange that we cannot hear the reports, for the wind is in our favour." "Too steady for rifle-firing," suggested the mate. "Looks to me like a bush fire." "By Jove, I hope not," said the sub earnestly. "The grass will catch like tinder." A minute or so passed, then Denbigh lowered his binoculars. "You're right, Armstrong," he said. "It is a fire. Those brutes have set the grass ablaze to cover their retreat." "Hark!" exclaimed the mate. Overhead came the unmistakable buzzing of an aerial propeller. One of the sea-planes, if not both, was returning. Seizing a flashing-lamp Denbigh directed it skywards. It was the only means at his disposal for communication. "All right?" he asked. A light blinked through the darkness. "_Dash, dot_. Pause. _Dash, dash, dash_" it flashed; then it ceased abruptly. Nevertheless the answer was to the point. It was NO. CHAPTER XXV Accounted For Before another quarter of an hour passed the long line of flames was visible to the naked eye. Fanned by the strong breeze the fire spread rapidly. It seemed as if its activity was by no means confined to the horseshoe loop formed by the river. It appeared to have obtained a grip upon the grass on the opposite bank. Once the flames attacked the mangroves there was no saying where the mischief might end. Denbigh could do little to aid his absent comrades, who, for aught he knew, might even now be overwhelmed by the swift advance of the devouring elements. Turning out the men who remained he had the quick-firer ammunition removed to the boats. Then setting fire to the grass around the bivouac he cleared a broad belt nearly a hundred yards in diameter. At all events the main fire would be checked before the flotilla was seriously imperilled.