LIST OF TREATISES 
309 
by B. Baldi (Augsburg, 1616), Thdvenot {Vet. math.), Kochly 
and Rlistow (1853) and by Wescher {Poliorcétique des Grecs, 
1867, the first critical edition). 
VI. The Cheirobalistra {"Hpoovos xeipofSaWiarpas KaraaKeurj 
Kai crupper pia (?)), edited by Y. Prou, Notices et extraits, xxvi. 2 
(Paris, 1877). 
VII. The geometrical works, Definitiones, Geometria, Geo- 
daesia, Stereometrica I and II, Mensurae, Liber Geeponicus, 
edited by Hultsch with Variae collectiones {Heronis Alexan 
drini geometrioorum et stereometricorum reliquiae, 1864). 
This edition will now be replaced by that of Heiberg in the 
Teubner collection (vols. iv, v), which contains much addi 
tional matter from the Constantinople manuscript referred to, 
but omits the Liber Geeponicus (except a few extracts) and the 
Geodaesia (which contains only a few extracts from the 
Geometry of Heron). 
Only fragments survive of the Greek text of the Mechanics 
in three Books, which, however, is extant in the Arabic (now 
edited, with German translation, in Heronis Opera, voi. ii, 
by L. Nix and W. Schmidt, Teubner, 1901). 
A smaller separate mechanical treatise, the BapovXKos, is 
quoted by Pappusd The object of it was ‘ to move a given 
weight by means of a given force ’, and the machine consisted 
of an arrangement of interacting toothed wheels with different 
diameters. 
At the end of the Dioptra is a description of a hodometer for 
measuring distances traversed by a wheeled vehicle, a kind of 
taxameter, likewise made of a combination of toothed wheels. 
A work on Water-clocks {vrepi vSpicor wpouKOTreiwv) is men 
tioned in the Pneumatica as having contained four Books, 
and is also alluded to by Pappus. 2 Fragments are preserved 
in Proclus {Hypotyposis, chap. 4) and in Pappus’s commentary 
on Book V of Ptolemy’s Syntaxis reproduced by Theon. 
Of Heron’s Commentary on Euclid's Elements only very 
meagre fragments survive in Greek (Proclus), but a large 
number of extracts are fortunately preserved in the Arabic 
commentary of an-Nairizi, edited (1) in the Latin version of 
Gherard of Cremona by Curtze (Teubner, 1899), and (2) by 
1 Pappus, vili, p. 1060. 5. 2 lb., p. 1026. 1.