the quadriga-yes , by god , it was ; the four horses ran abreast , threatening at every moment to overturn the chariot that bounced like a pebble in their wake-galloped on , held in perilous check by the one-armed maniac who stood upright behind them , a terrified groom with a whip beside him , clinging with one hand to the chariot and with the other to the graf von namtzen .