This "chariot-seat"-- philologically no other explanation can well be given (comp.

Servius ad Aen.i.

16)--is most simply explained by supposing that the king alone was entitled to ride in a chariot within the city (v.

The King)--whence originated the privilege subsequently accorded to the chief magistrate on solemn occasions--and that originally, so long as there was no elevated tribunal, he gave judgment, at the comitium or wherever else he wished, from the chariot-seat.
2.

I.V.The Housefather and His Household 3.