Dick now came to his determination. At about a foot above the water-level, that is, about seven feet from the ground, he resolved to bore a hole through the clay. If he should find himself in communication with the open air, he would have the proof he desired that the top of the cone was still uncovered; if, on the other hand, he should ascertain that he had pierced the wall below the surface of the external water, he would be prepared to plug up the hole instantaneously, and repeat the experiment higher up. It was true that the inundation might have risen even fifteen feet above the plain; in that case the worst had come, and there was no alternative but that they must all die of asphyxia.
Carefully considering the chances of his undertaking, Dick calmly and steadily set about his task. The best instrument that suggested itself for his purpose was the ramrod of a gun, which, having a sort of corkscrew at the end for extracting the wadding, would serve as an auger. The hole would be very small, but yet large enough for the requisite test. Hercules showed him all the light he could by holding up the lantern. There were several candles left, so that they were not in fear of being altogether in darkness.
The operation hardly took a minute; the ramrod passed through the clay without difficulty; a muffled sound was distinguished as of air-bubbles rushing through a column of water. As the air escaped, the water in the cone rose perceptibly. The hole had been pierced too low. A handful of clay was immediately forced into the orifice, which was thus effectually plugged; and Dick turned round quietly, and said,-
"We must try again."
The water had again become stationary, but its last rise had diminished the amount of breathing space by more than eight inches. The supply of oxygen was beginning to fail, respiration was becoming difficult, and the flame of the candle burned red and dim.
About a foot higher than the first hole, Dick now set about boring a second. The experiment might again prove a failure, and the water rise yet higher in the cone; but the risk must be run.
Just as the auger was being inserted, a loud exclamation of delight was heard proceeding from Cousin Benedict's cell. Dick paused, and Hercules turned the lantern towards the excited naturalist, who seemed beaming with satisfaction.
"Yes, yes; I see it all well enough," he cried; "I know now why the termites left their home; they were wide-awake; they were more clever than we are; they knew that the storm was coming!"
Finding that this was all the worthy entomologist had
[Illustration: All fired simultaneously at the nearest boat.]