six o'clock
Robin had gone with him ; but Dr Thorpe remained at home . For a time there was nothing but silence . The usual hum of the City was stilled : everybody was at Westminster . From Goodman 's Fields the cows came lowing home ; now and then a single person , intent on business with which nothing might interfere , passed quickly up the Minories ; the soft chime of the bells of Saint Katherine floated past the Tower wall , for the ringers were practising after evensong ; and one great gun rang out sharply from the Tower , to inform the world that it was six o'clock . Five minutes afterwards , a low sound , like the roll of distant thunder , came from the City side of Aldgate . It grew louder every moment . It became first a noise , then a roar .