In this part of Lord of the Flies, Piggy has just been brutally killed by Roger who pushed a rock off the ledge onto Piggy. This was the most savage act committed on the island because it was premeditated. Roger is developing as an even more savage, power-hungry leader than Jack is. In this same passage at the end of chapter 11, Roger edges by Jack and just barely misses hitting Jack with his shoulder. This action, though subtle in observation, means a great deal in the shift of power. While Jack hungered for power and he wanted the other kids on the island to see him as the supreme person in charge, Roger wants power because it would give him the ability to be cruel at will. The nameless authority that he is wielding is just that - authoritarian power. We have already seen that Roger hungers for the ability to hurt others. In chapter 4, he throws stones toward Henry for no reason, but he purposely doesn't hit Henry because he's held back by the rules of the society from which he came. Those rules and that society no longer exists. Any remnants of it were crushed along with Piggy.