Concerning Hero of Alexandria, the author of the treatise here
translated, little is known with certainty. When his name and the place
of his abode have been given, all that can be positively affirmed is
exhausted. We are further told by Hero the younger, who is supposed to
have written in the seventh century A. D., that Hero, the author of
the “Pneumatics,” was a pupil of Ctesibius;—a statement sufficiently
probable from the character of his works, and strengthened by the
inscription Ἥρωνος Κτησιβίου[1] prefixed to another work by Hero on the
construction of missiles.
Even the precise period at which Hero lived is a debated point. From
his own writings all that can be gathered is that he knew the works
of Archimedes, and of Philo the Byzantian, who, again, is known to
have been a contemporary of Ctesibius; and, as the earliest mention of
him by others is as low down as the fourth century A. D., external
evidence, even if it were distinct, would be little trustworthy. Such
evidence, however, is vague and scanty. The only direct statement
bearing on the date of Hero is the assertion that he was the pupil of
Ctesibius. The date of Hero therefore depends on the date of Ctesibius,
and this has been variously fixed by different chronologists.
Clinton, (F. H. vol. iii. pp. 535, 538,) who puts Hero as low down
as the end of the second century B. C., proceeds on the following
evidence: Athenæus (vol. iv. p. 174, edit. Schweighæuser) quotes one
Aristocles as saying, in a work περὶ χορῶν, of the water-organ, φασὶ
τοῦτο εὑρῆσθαι ὑπὸ Κτησιβίου κουρέως ἐνταῦθα οἰκοῦντος ἐν τῇ Ἀσπενδίᾳ
ἐπὶ τοῦ δευτέρου Εὐεργέτου· διαπρέψαι τέ φασι μεγάλως. Now Euergetes
II. (Ptolemy VII.) reigned from B. C. 170 to B. C. 117, and hence
Clinton assigns Hero, the pupil of Ctesibius, to the reign of Ptolemy
VIII. that is, to B. C. 117–81.
Fabricius, on the other hand, (Bibi. Græc. vol. iv. pp. 222, 234,
edit. Harl.) setting out from an entirely different datum, places him
more than a hundred years earlier, in the time of Ptolemy Philadelphus
(Euergetes I.): Athenæus Mechanicus, (one of the mechanical writers
whose works are printed in the _Veterum Mathematicorum Opera_), in his
treatise περὶ μηχανημάτων, p. 8, speaks of Ctesibius as a contemporary;
his words are Κτησίβιος ὁ Ἀσκληνὸς, ὁ ἐν Ἀλεξανδρείᾳ μηχανικός. This
treatise is dedicated to a Marcellus, and Fabricius, assuming, after
Hero junior, this Marcellus to be the conqueror of Syracuse, has hence
assigned Ctesibius and Hero to the reigns of the second and third
Ptolemies (B. C. 285–222).
Of these conflicting dates that assigned by Clinton has been generally
adopted. The question is discussed at some length by Schweighæuser,
in a note on the passage of Athenæus referred to above: he deems the
identification of the patron of Athenæus Mechanicus with the conqueror
of Syracuse to be unwarranted, and, besides, thinks it most unlikely
that at so early a period a Greek should dedicate a work on military
engines to any Roman. But from the expression employed by Athenæus,
(ὦ σεμνότατε Μάρκελλε,) it may be inferred that his patron was a
man of very exalted rank; and the second objection from the alleged
improbability that a Greek should dedicate such a work to a Roman at
that period will hardly be thought to apply at the period referred
to, while the skill displayed by Marcellus in the siege of Syracuse,
and the regret expressed by him for the fate of Archimedes, (whether
genuine or not,) may well have suggested the dedication to him of
a work on military engineering. The assumption of Fabricius, then,
is, in itself, not to be too hastily rejected; and it will be seen
that it is not so irreconcileable with the statement of Aristocles
as has been supposed. Fabricius has carried back the date further
than his argument requires or even warrants. Marcellus was killed B.
C. 208: Athenæus might have inscribed his work to him about B. C.
212 or 210; at this period, then, we must suppose Ctesibius to have
been known as a philosopher,[2] but he may have lived far into the
succeeding century,—possibly even into the reign of Euergetes II. (B.
C. 170–117); Hero would thus be placed about B. C. 150, a result by
no means inconsistent with the statement of Aristocles, since it is
not necessary, with Clinton, to assign the whole of the long reign of
Euergetes II. to Ctesibius, and then to put Hero so low down as the
reign of Ptolemy VIII.
The treatise on Pneumatics was first published in an Italian
translation by Aleotti (Bologna, 1547). In 1575 appeared a Latin
version by F. Commandine (Urbino, 1575): this translation, through
which the work has been most extensively known, was reprinted at
Amsterdam and at Paris. Several other translations were made into
Italian, and one into German (see Fabricius, iv. p. 235). It was not
till the year 1693, and subsequently to the appearance of all the
versions named above, that the Greek text was published at Paris in
the _Veterum Mathematicorum Opera_. The design of this collection was
formed by Thevenot, deputy librarian of the Royal library in the reign
of Louis XIV., and after his death it was carried out by De la Hire.
Thevenot’s plan was to publish an accurate transcript of the MSS. of
the several authors. The inevitable obscurity arising from the numerous
corruptions which had crept into the manuscripts was to be remedied by
an appendix of notes and a Latin translation. But for the Pneumatics of
Hero it seemed sufficient to adopt the already well-known translation
of Commandine; and, in consequence, of the eight MSS. of this treatise
existing in the Royal Library, that one was chosen which most nearly
agreed with the Latin version. This MS. was closely followed, and,
as might be expected, the printed text is extremely corrupt: not
unfrequently entire clauses are wanting, which, ending with the same
word as the clause preceding, seem to have been passed over by the
transcriber, whose eye, in returning from his copy to the original,
rested on the second instead of the first of the two similar words.
These defective passages, which appear to have been conjecturally
restored by Commandine, have been supplied in the present translation
from MSS. of Hero preserved in the British Museum. These MSS. are
described in the appendix, where the most important cases in which the
printed text has been supplemented, or otherwise amended, from this
source are collected. When any words are included in the translation
between brackets, it is to be understood that they appear neither in
the text nor in any of the MSS. collated, but have been inserted as
necessary to the sense.
The other treatises of Hero are:—1. On the construction of slings. 2.
On the construction of missiles. 3. On automata. These are published in
Greek and Latin in the _Vet. Math._ 4. On the method of lifting heavy
bodies. This treatise has not yet been edited: it exists only in an
Arabic translation. 5. On the “dioptra” or spying-tube: also inedited.
It exists in manuscript in the Royal Library at Vienna, and among the
MSS. of Hero contained in the Library of the University of Strasburgh.
Schweighæuser in his notice of these MSS. (ap. Fabric. iv. p. 226),
intimates that this treatise is of much interest, and contains an
account of the dioptra “newly invented or improved by Hero himself.”
Some help might perhaps be derived from it towards the settlement of
Hero’s date, as the dioptra is mentioned and minutely commented on by
Polybius. Several other treatises, entirely lost, are enumerated by
Fabricius, iv. p. 236.
A question of great interest presents itself as to the claim of
Hero to be considered as the inventor of the several machines and
methods described by him. In the introduction of the “Pneumatica” he
declares that his purpose is to arrange in order the discoveries of
his predecessors, and to add to them his own. The treatise on the
construction of missiles is ascribed in some MSS. to Ctesibius, (as
in one at Leyden, Fabric. iv. p. 229,) while at the end of a MS. of
the same work in the Library of Vienna are these words, τέλος τῶν
Ἀρχιμήδους Βελοποιΐκῶν, τῶν ἐξηγηθέντων παρὰ Ἥρωνος Κτησιβίου. Again,
it is singular that neither Pliny nor Vitruvius has any reference to
Hero, though Ctesibius and his inventions are repeatedly mentioned.
Vitruvius (x. 7) minutely describes a machine for raising water to a
great height, which he expressly ascribes to Ctesibius; and in the
following chapter he treats, at great length, of the construction
of water-organs, yet without any notice of Hero. Both Pliny and
Vitruvius expressly name Ctesibius as famous for his skill in the
invention of pneumatic and hydraulic instruments. Pliny’s words are
(vii. 38) “Laudatus est Ctesibius pneumatica ratione et hydraulicis
organis repertis.” Vitruvius, (x. 7, compare also ix. 8,) after his
description of the machine for raising water, says “Nec tamen hæc sola
ratio Ctesibii fertur exquisita, sed etiam plures et variis generibus
ab eo liquore pressionibus coacto spiritus efferre ab natura mutuatos
effectus ostenduntur, uti merularum aquæ motu voces, atque engibata,
quæ bibentia tandem movent sigilla, cæteraque quæ delectationibus
oculorum et aurium usu sensus eblandiuntur.” He refers the curious to
the commentaries of Ctesibius himself. How well this description of
Ctesibius’ inventions suits the general character of those preserved
by Hero, will be manifest at once. Vitruvius, as Schneider has pointed
out,[3] seems to have had no knowledge of Hero’s Pneumatics, as both
the forcing-pump and the water-organ differ in several important
particulars from those of Hero: he does not even notice the application
of the forcing-pump in extinguishing conflagrations. This silence on
the part of Vitruvius and Pliny, so remarkable on the supposition that
Hero was an original discoverer, is more easily accounted for if we
regard him rather as the interpreter of Ctesibius.[4]
For further details on the life and writings of Hero, the reader
is referred to Fabricius, iv. pp. 222–239, Smith’s Dictionary of
Biography, and Baldi _de Vita Heronis_, in his edition of the Belopœica.