Roger of Hereford

Roger of Hereford (sometimes Rogerus Herefordensis or Roger Infans or Roger Puer; flourished 1176–1198) was a medieval astronomer active at Hereford in the period 1178 to 1198.

Nothing is known of Roger's nationality or when he was born nor of his education. He first appears in the historical record in 1176, when he wrote a computus, a treatise on calculating ecclesiastical dates for Gilbert Foliot, who had previously been Bishop of Hereford but was at that time Bishop of London. In this computus, Roger criticized the work of Gerland, which was the standard work at the time on calculating ecclesiastical dates, and drew on Hebrew and Arabic learning.

Roger's connections with Hereford are shown by the fact that he wrote a set of tables showing the meridian of Hereford in 1178. He is probably the same person as the Roger Infans who was a witness on charters at Hereford in the time frame 1186 to 1198.

Another work of Roger's was an astronomical treatise covering most aspects of the subject. Entitled Liber de Quatuor Partibus Judiciorum Astronomie, it drew on earlier works by Raimond de Marseille, and the translations of Arabic works performed by Juan de Sevilla and Hermann of Carinthia. Besides the above works, manuscripts assign works on astrology and alchemy to Roger, although these works do not survive.

Roger was the dedicatee of a translation made by Alfred of Shareshill. Roger may also be responsible for a new method of calculating horoscopes.

Roger was an important scholar in transmitting the knowledge of Adelard of Bath and others of a previous generation to a new generation of scholars, including Robert Grosseteste, who was a young member of the same household with Roger during Roger's later years at Hereford.