This essay deals chieﬂy with the Reign of the Emperor Probus. But the essential preliminary to an investigation of the reign of any emperor who ruled between a.d. 117 and 285 is an exam ination of the Augustan History, and therefore considerable space has necessarily been devoted to a discussion of the views which have been put forward, from time to time, by so many scholars. The controversy as to the date and authenticity of the Augustan History has been maintained chieﬂy by German, Italian and French scholars, and, so far as I am' aware, no monograph dealing with the subject has yet appeared in England. Miss Orma Fitch Butler, of the Oxford College for Women (ohio), in Studies in the Life of Helioga balus has recently discussed the question of the authorship of the Augustan History. The conclu sions to which I have come were arrived at before I had had the advantage of seeing her work.