In a short time, however, it was perceived by those on board the ship that a change had taken place in the appearance of the crabs; the visible portion of their backs was growing larger and larger; they were rising in the water. Their mailed roofs became visible from end to end, and the crowd of observers looking down from the ship were amazed to see what large vessels they were. Higher and higher the crabs arose, their powerful air-pumps working at their greatest capacity, until their ponderous pincers became visible above the water. Then into the minds of the officers of the Llangaron flashed the true object of this uprising, which to the crew had seemed an intention on the part of the sea-devils to clamber on board. If the cylinder were left in its present position the crab might seize the chains by which it was suspended, while if it were raised it would cease to be a defence. Notwithstanding this latter contingency, the order was quickly given to raise the cylinder; but before the hoisting engine had been set in motion, Crab Q thrust forward her forceps over the top of the cylinder and held it down. Another thrust, and the iron jaws had grasped one of the two ponderous chains by which the cylinder was suspended. The other end of the cylinder began to rise, but at this moment Crab R, apparently by a single effort, lifted herself a foot higher out of the sea; her pincers flashed forward, and the other chain was grasped. The two crabs were now placed in the most extraordinary position. The overhang of their roofs prevented an attack on their hulls by the Llangaron, but their unmailed hulls were so greatly exposed that a few shot from another ship could easily have destroyed them. But as any ship firing at them would be very likely to hit the Llangaron, their directors felt safe on this point. Three of the foremost ironclads, less than two miles away, were heading directly for them, and their rams might be used with but little danger to the Llangaron; but, on the other hand, three swift crabs were heading directly for these ironclads. It was impossible for Crabs Q and R to operate in the usual way. Their massive forceps, lying flat against the top of the cylinder, could not be twisted. The enormous chains they held could not be severed by the greatest pressure, and if both crabs backed at once they would probably do no more than tow the Llangaron stern foremost. There was, moreover, no time to waste in experiments, for other rams would be coming on, and there were not crabs enough to attend to them all. No time was wasted. Q signalled to R, and R back again, and instantly the two crabs, each still grasping a chain of the cylinder, began to sink. On board the Llangaron an order was shouted to let out the cylinder chains; but as these chains had only been made long enough to allow the top of the cylinder to hang at or a little below the surface of the water, a foot or two of length was all that could be gained.