Instantly the sea began to boil up around him like a young geyser. The sand was swept and swirled in every direction by the column of compressed air that was boring relentlessly into everything it touched. The young diver could feel his feet sinking slowly into an aperture as the sea bottom was scooped up and distributed into the yellow clouds that filled all the space of water around the periscope pole. A new danger confronted the youth. Unless he exercised extreme caution he might dig his own grave. The shifting sand might collect around his own body and imbed him quickly unless he kept it shifting away from him instead of around him. The thought of being buried alive made him shudder for an instant, but he dismissed it and set himself carefully to keep the moving sand in front instead of behind him. He resolved to keep on the move, holding the air hose ever far in front and drawing himself, as best he could shift the weights that held him down, in a wide circle around the periscope pole, throwing the sand off to the left. In this way he hoped to make an excavation that would gradually bring the conning tower of the U-boat above the level of the sea bottom. Backing steadily all the time on the circumference of his circle, he kept the sand moving ever outward; and move it did with the assistance of the undertow that aided and abetted the work of the air hose just as Jay had anticipated it would do. Despite the perils of the undertaking Jay persisted and soon had worked himself completely around to the starting-point, a complete circle having the periscope pole of the U-boat as the hub of the imaginative wheel. By the feel of it under his feet and by thrusting his right foot out into the hole that he had dug Jay could tell his efforts had not been in vain. Considerable sand must have been shifted. He decided to turn off the compressed air and await the clearing of the water so that he could see what he had accomplished. He had by now been down for considerable time and was commencing to feel the effects of his hard toil, the wear and tear of the sea, and the weight of his added incumbrances. Nevertheless, since his breathing was still free and easy he decided he could risk a few more minutes anyway to view the results of his handiwork. By and by the sand clouds began to settle and the yellow sedimentation to subside. Imagine his joy when he found that he had successfully dug a great excavation right over the deck of the U-boat amidships, with the conning tower standing out entirely freed of all sand investiture. "Good enough," he told himself gleefully. "And now to get inside the U-boat before the sands shift back again." Reluctantly he gave the signal to be raised away after lashing the air hose with which he had successfully accomplished the task fast to the conning tower of the U-boat.