What does "assumed a tenfold austerity of brow" mean in this context? Here a general shout burst from the bystanders—“A tory! a tory! a spy! a refugee! hustle him! away with him!” It was with great difficulty that the self-important man in the cocked hat restored order; and, ***having assumed a tenfold austerity of brow***, demanded again of the unknown culprit, what he came there for, and whom he was seeking? The poor man humbly assured him that he meant no harm, but merely came there in search of some of his neighbors, who used to keep about the tavern. “Well, who are they? Name them.” Rip bethought himself a moment, and inquired, “Where’s Nicholas Vedder?” There was a silence for a little while, ... This is from the short story, Rip Van Winkle, and I don't have any idea what the part marked in stars means, especially because I'm not sure which definition of these words in the dictionary fits in this context. Please let me know if you need more context. Thanks in advance!