preparing the intrenchment in the courtyard, so that by destroying the connecting walls, he could separate the southwest tower from the rest, and thus, if tho enemy should breach the southern wall, cut them off from the great keep and the two other towers. Friar Bacon looked attentively at the diagram.
"But how," he asked in a few moments, "are you going to destroy the walls?"
"I have already begun digging away the earth beneath," Hugh answered, marking the two places where he meant to throw down the wall. "Then, having propped up those parts with heavy timbers, I can smear them with pitch, set fire to them, and down they will go!"
"The ignorant have often accused me of a knowledge of the 'black art,’" said the monk with a smile. "But with two men like yourselves it is not necessary for me to say that I am only a poor scholar, and no servant of the Evil One. Yet there is a certain black powder which I have learned to make that might well cause me to be considered a dealer in magic. If you will keep my counsel, and will believe me when I tell you that I am no more than a student of nature's secrets, I will show you an experiment that may give our young lord good reason to be glad he was hospitable to the poor brother of St. Francis."
