For this, and the other dignities of the empire, it may be sufficient to refer to the ample commentaries of Pancirolus and Godefroy, who have diligently collected and accurately digested in their proper order all the legal and historical materials. From those authors Dr. Howell (History of the World, vol. ii. p. 24-77) has deduced a very distinct abridgment of the state of the Roman empire.