The distant rumbling sound now became louder from time to time, and at moments shook the walls of his prison, then died away to a faint murmur.
Frederick-Christian now tried to collect his thoughts upon the situation and bring some sort of order to his mind.
Susy d'Orsel was dead ...
The King had felt no deep love for the girl. Still, he had been fond of her in a way and her sudden death affected him deeply.
He himself was a prisoner. But a prisoner of whom? Evidently of those who had killed his mistress. Again, in all probability, they did not contemplate killing him since they had had the opportunity to do so and he was still alive and unharmed. This being so, they would not let him die of hunger and thirst.
His watch had stopped and he had no way of measuring the lapse of time; but his attention was called to the fact that the rumbling noises were happening at greater intervals.
"The pulse-beats of a man are separated by intervals of a second," he thought, "and by counting my pulse I can determine the interval between the rumbling, and thus gain some idea of the passing hours."
He was about to put this plan into practice when a sudden cry escaped him:
"Good God!"
In the blackness of his cell a thin shaft of light appeared.