"Try them, Pencroft," replied the engineer. "However, I think that in making the experiment, we ought to employ, not the ordinary powder, the supply of which, I think, should remain untouched, but the pyroxile which will never fail us." "Can the cannon support the shock of the pyroxile?" asked the reporter, who was not less anxious than Pencroft to try the artillery of Granite House. "I believe so. However," added the engineer, "we will be prudent." The engineer was right in thinking that the guns were of excellent make. Made of forged steel, and breech-loaders, they ought consequently to be able to bear a considerable charge, and also have an enormous range. In fact, as regards practical effect, the transit described by the ball ought to be as extended as possible, and this tension could only be obtained under the condition that the projectile should be impelled with a very great initial velocity. "Now," said Harding to his companions, "the initial velocity is in proportion to the quantity of powder used. In the fabrication of these pieces, everything depends on employing a metal with the highest possible power of resistance, and steel is incontestably that metal of all others which resists the best. I have, therefore, reason to believe that our guns will bear without risk the expansion of the pyroxile gas, and will give excellent results." "We shall be a great deal more certain of that when we have tried them!" answered Pencroft. It is unnecessary to say that the four cannons were in perfect order. Since they had been taken from the water, the sailor had bestowed great care upon them. How many hours he had spent, in rubbing, greasing, and polishing them, and in cleaning the mechanism! And now the pieces were as brilliant as if they had been on board a frigate of the United States' Navy. On this day, therefore, in presence of all the members of the colony, including Master Jup and Top, the four cannon were successively tried. They were charged with pyroxile, taking into consideration its explosive power, which, as has been said, is four times that of ordinary powder: the projectile to be fired was cylindro-conic. Pencroft, holding the end of the quick-match, stood ready to fire. At Harding's signal, he fired. The shot, passing over the islet, fell into the sea at a distance which could not be calculated with exactitude. The second gun was pointed at the rocks at the end of Flotsam Point, and the shot, striking a sharp rock nearly three miles from Granite House, made it fly into splinters. It was Herbert who had pointed this gun and fired it, and very proud he was of his first shot. Pencroft only was prouder than he! Such a shot, the honour of which belonged to his dear boy. The third shot, aimed this time at the downs forming the upper side of Union Bay, struck the sand at a distance of four miles, then having ricocheted, was lost in the sea in a cloud of spray.