Dictionary of National Biography, 1885-1900/John of London (fl.1267)
JOHN (fl. 1267), called of London, mathematician, born about 1246, was a poor boy of fifteen when he attracted the notice of Roger Bacon [q. v.], who caused him to be instructed in languages, mathematics, and optics. Bacon speaks of him as one of the only two perfect mathematicians of his time (Opus Tertium, c. xi.); and when in 1267 he sent John to Rome to present his 'Opus Majus,' 'Opus Minus,'and 'Opus Tertium' to Pope Clement IV, to explain difficulties, and exhibit certain experiments, there was no (Bacon wrote) whom he could employ with so much satisfaction (ib. c. xix.) Bacon is said to have received him into the order of St. Francis. Some have supposed that he is identical with John Peckham [q. v.], the archbishop of Canterbury. Tanner ascribes to him two treatises,(l)'De Trigonio Circinoque Analogico,' (2) 'De Speculis Comburentibus,' both of which ore preserved in Cott. MS. Vit C. vii. It is possible that some of the works which pass under the name of Bacon are by John of London, In Vatican MS. 3202 there is a treatise styled 'Joannes de Ponderibus,' along with a number of Bacon's minor works.
[Bale, xiii. 81; Pits, p. 878; Tanner's Bibl. Brit.-Hib. p. 436; Leland's Collect. ii. 40; Sbaralea's Suppl. in Script. Ord. S. Francisc. p. 437; Bacon's Opus Tertium, cc. xi. and xix.; Opus Majus, i. c. x.; Brewer's Preface to his Opera Inedita R. Bacon in Rolls Ser.]