EUCLID, EkNeOnc, The most famous of the Greek writers on geom etry who flourished at Alexandria. is known of his life except that Proelus tells us that be lived in the tune of Ptolemy I. (who reigned B.C. 306-'283). It is probable that the period of his greatest activity was in the neighborhood of n.e. 300. llis fame was so great among the Greeks that he was called it crocieudrhc,`the author of the Elements,' and even to-day' the name Euclid is synonymous with elementary geometry. II is Iroixaa, or 'Elements,' were well known to the Arabs, a portion having been translated in the time of Ilarun-a1-1Zashbl, a second (complete) translation being made under Al-Mamun and oth ers appearing later. It was translated from Arabic into Latin by Adelard of Bath (c.1120) , from a copy obtained in Spain; and this translation, under the name of Giovanni Campano (1260), was printed in 1482 at Venice. Iiillingsley's translation from
the Latin into English appeared in 1570. The extant works unquestionably ascribed to Euclid are the Elements (Irot•ria); the Data (Jedokiera); the Phenomena (bcor6ka Ca); 'the Optics ('Orroai) ; the Reflections (Karorrpl ); the Di cis ion of the Seale (KaTorokch scicoro;) , and a work, be DkisiuniLus, known only through the Arabic. The best editions of Euclid's works are: Peyrard, Les alleles d'Euel-id en. yrec, cn latin et en fruneals (Paris, 3 vols., 1814-18) Heiberg and Menge, Oataiu (Leipzig. 7 vols., 1SS3-96). One of the best biographies of Euclid is that by De Mor gan, in Smith's Dictionary of Greek and Roman Biography (under EUCLE1DES) . Consult, also: Cow, History of Greek Mathematics (Cambridge, I884), and the authorities referred to under MATHEmAncs.