their movement was checked by the mass of people in front , who were no longer moving , but they were still being pushed onwards from behind ; the crowd became denser and more closely packed , yet despite the jostling and pushing , the occasional surge of movement backwards or forwards as the pressure grew , no one spoke , so that the only sound was that of thousands of feet treading a slow rhythm , and the occasional crack of resin spitting from one of the torches , and the distant crackling of the great fires .