CONTROVERSIES AS TO HERON S DATE 307
Heron was known as о ’AXegarSpevs (e.g. by Pappus) or
о /11-¡yaviKos (mechanicus), to distinguish him from other
persons of the same name; Proclus and Damianus use the
latter title, while Pappus also speaks of oi тгер! той "Hpcoua
pr/^avLKoi.
s Character of works.
Heron was an almost encyclopaedic writer on mathematical
and physical subjects. Practical utility rather than theoreti
cal completeness was the obj ect aimed at; his environment in
Egypt no doubt accounts largely for this. His Metrica begins
with the old legend of the traditional origin of geometry in
Egypt, and in the Dioptra we find one of the very problems
which geometry was intended to solve, namely that of re
establishing boundaries of lands when the flooding of the
Nile had destroyed the land-marks: ‘ When the boundaries
of an area have become obliterated to such an extent that
only two or three marks remain, in addition to a plan of the
area, to supply afresh the remaining marks.’ 1 Heron makes
little or no claim to originality; he often quotes authorities,
but, in accordance with Greek practice, he more frequently
omits to do so, evidently without any idea of misleading any
one; only when he has made what is in his opinion any
slight improvement on the methods of his predecessors does
he trouble to mention the fact, a habit which clearly indi
cates that, except in these cases, he is simply giving the best
traditional methods in the form which seemed to him easiest
of comprehension and application. The Metrica seems to be
richest in definite references to the discoveries of prede
cessors; the names mentioned are Archimedes, Dionysodorus,
Eudoxus, Plato; in the Dioptra Eratosthenes is quoted, and
in the introduction to the Catoptrica Plato and Aristotle are
mentioned.
The practical utility of Heron’s manuals being so great, it
was natural that they should have great vogue, and equally
natural that the most popular of them at any rate should be
re-edited, altered and added to by later writers; this was
inevitable with books which, like the Elements of Euclid,
were in regular use in Greek, Byzantine, Roman, and Arabian
1 Heron, Dioptra, c. 25, p. 268. 17-19,
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