ten o'clock
I waited from this time the greater part of a week , that I might have the benefit of a bright moonlight . It was necessary that I should work in the night ; it was necessary that my operations should be performed between the last visit of the keepers at night and their first in the morning , that is , between nine in the evening and seven . In my dungeon , as I have already said , I passed fourteen or sixteen hours of the four-and-twenty undisturbed ; but since I had acquired a character for mechanical ingenuity , a particular exception with respect to me was made from the general rules of the prison . It was ten o'clock when I entered on my undertaking . The room in which I was confined was secured with a double door . This was totally superfluous for the purpose of my detention , since there was a sentinel planted on the outside . But it was very fortunate for my plan ; because these doors prevented the easy communication of sound , and afforded me tolerable satisfaction that , with a little care in my mode of proceeding , I might be secure against the danger of being overheard .