3. The younger, so called because we have not even an adjective of place to distinguish him from Heron of Alexandria, is supposed to have lived under Heraclius (A. D. 610-641).
In his own work on Geodesy (a term used in the sense of practical geometry), he says that in his own time the stars had altered their longitudes by seven degrees since the time of Ptolemy: from which the above date must have been framed.
But if he spoke, as is likely enough, from Ptolemy's value of the precession of the equinoxes, without observing the stars himself, he must have been about two hundred years later.
He was a Christian.
The writings attributed to Heron the younger are,--
There is one Greek manuscript at Bologna.
Published (Lat.) by Barocius, Venice, 1572, 4to.
Montucla notices this as the first treatise in which the mode of finding the area of a triangle by means of its sides occurs. Savile, who had a manuscript of this treatise, rejects with scorn the idea of its having been written by Heron; but we suspect that he supposed it to be attributed to Heron of Alexandria.
published (Lat.) with the above by Barocius.
Published (Gr.) in the Veter. Mathemat. Opera, &c. mentioned in the life of Heron of Alexandria.
This exists only in manuscript.
Published (Gr. Lat.) with the first book of Euclid, by Dasypodius, Strasburg, 1571, 8vo.
(Gr. Lat.), in the Analecta Graeca of the Benedictines, vol. i. Paris, 1688, 4to.
This work exists only in manuscript.
Fabric. Bibl. Graec.
vol. iv. p. 237 ; Heilbronner, Hist. Mathes. Univ.;
Montucla, Hist. des Mathém.