On Weights and Measures is a historical, lexical, metrological, and geographical treatise compiled in 392 AD in Constantia by Epiphanius of Salamis (). The greater part of the work is devoted to a discussion on Greek and Roman weights and measures.

The composition was written at the request of a Persian priest, sent to Epiphanius by letter from the Roman emperor in Constantinople. Although five fragments of an early Greek version are known to exist, with one entitled (), added by a later hand, this Syriac version is the only complete copy that has survived. Partial translations in Armenian and Georgian are also known to exist. Its modern title belies its content, as the work also contains important historical anecdotes about people and places not written about elsewhere.

Two manuscripts of On Weights and Measures, written in Syriac on parchment, are preserved at the British Museum in London. The older was found in Egypt and, according to the colophon, was written in the Seleucid era, in "nine-hundred and sixty-[...]" (with the last digit effaced, meaning, that it was written between the years 649–659 AD).William Wright, Catalogue of Syriac manuscripts in the British Museum 2 756 (pp. 717–718)

The first to attempt a modern publication of Epiphanius' work was Paul de Lagarde in 1880, who reconstructed the original Syriac text by exchanging it with Hebrew characters,Paul de Lagarde, Veteris Testamenti ab Origene recensiti fragmenta apud Syros servata quinque. Praemittitur Epiphanii de mensuris et ponderibus liber nunc primum integer et ipse syriacus, Gootingae 1880 and who had earlier published excerpts from several of the Greek fragments treating on weights and measures in his Symmicta.Paul de Largarde, Symmicta I, Göttingen 1877, pp. 210–225 In 1973, a critical edition of the Greek text was published by E.D. Moutsoulas in Theologia.E.D. Moutsoulas, ed., "Epiphanius of Salamis, Concerning Weights and Measures" (Introduction, Commentary, Text and Notes), Theologia, 44 (1973), pp. 157–198

Synopsis Part One In folios [54b–55c], Hadrian's journey and arrival in the East is dated "47 years after the destruction of Jerusalem." Translations In folios [47a–49a]; [51d–52a]; [56d–57b] Epiphanius names four major translations of the Hebrew Bible, made in the Greek tongue: the LXX made by the seventy-two translators, another by Aquila of Pontus, one by Theodotion, and yet another by Symmachus. A fifth Greek translation was discovered in wine jars in Jericho, and a sixth in Nicopolis near Actium. Afterwards, Origen arranged six columns of the extant Greek translations and two of the Hebrew side by side, naming it the Hexapla. Epiphanius expands his description of the translation of the seventy-two translators (known as the Septuagint) and how they were assigned thirty-six cells, two to each cell, on the Pharian island. Two translators translated the Book of Genesis, another two the Book of Exodus, another two the Book of Leviticus, and so forth, until the entire 22 canonical books of the Hebrew Bible (today there are 24) had all been translated into the Greek tongue. The seventy-two translators were drawn from the twelve tribes of Israel, six men to each tribe who were skilled in the Greek language.

In folios [49a–50a] Epiphanius gives a description of the canonical books of the Hebrew Bible and translations made of the same. In his day, he notes that the Scroll of Ruth and the Book of Judges were joined together, and considered as one book. So, too, the Books of Ezra and Nehemiah were joined, and considered as one book, as were First and Second Chronicles (Paraleipomena) considered as one book, as were the First and Second Samuel (Book of First and Second Kingdoms) considered as one book, and the First and Second Kings (Book of Third and Fourth Kingdoms) considered as one book.

Part Two Prominent figures In spite of Epiphanius' interest in Jewish themes, his narrative often takes on a distorted and stereotypical view of Judaism. Still, he is an invaluable source on the lives of people and places that figure highly in Jewish lore. In folios [54a–55c]; [55c–55d] Epiphanius treats on the lives of two prominent persons who became proselytes to the Jewish religion; the one Aquila (known also as Onkelos) who was a relation of Hadrian, and whom he made the overseer of Jerusalem's rebuilding around 115 AD. The other person of interest who is described by him is Symmachus, also known as Sūmkos () in rabbinic literature.See: Mishnah Eruvin 3:1; Baba Metzia 6:5; Ḥullin 5:3 in The Mishnah (ed. Herbert Danby), Oxford University Press, 1974; the Babylonian Talmud Eruvin 13b, Baba Bathra 73a, Baba Kamma 46a, et al. Symmachus is mentioned as belonging originally to the Samaritan nation, and is said to have converted to Judaism during the reign of Verus. He subsequently underwent a second circumcision and became a disciple of Rabbi Meir.Babylonian Talmud Eruvin 13b Symmachus belonged to the fifth generation (165–200 CE) of Rabbinical teachers referred to in the text of the Mishnah.The Mishnah (ed. Herbert Danby), Oxford University Press: Oxford 1977, Appendix III, pp. 799–800 The Emperor Hadrian is said to have passed through Palestine while en route to Egypt, some 47 years after the destruction of Jerusalem.

Part Three Weights and Measures Folios [61d–73b] contain a treatise on the known weights and measures used in his day among the Hebrews, the Greeks and the Romans. He states the equivalent weights for the kab (cab), kor, the lethekh (Lethek), homer, bath, modius (Hebrew: seah = lit. "measure"),A measure of capacity equivalent to the volume of 144 medium-sized eggs (about 8.5 litres); Marcus Jastrow, Dictionary of the Targumim, the Talmud Babli and Yerushalmi, and the Midrashic Literature (2nd edition), Massachusetts 2006, s.v. מודיא p. 738. . Herbert Danby (ed.), The Mishnah, Oxford University Press: Oxford 1977, Appendix II (Liquid and Dry Measure), p. 798 , who, like all the earlier and later rabbinic writers, prescribe 6 kabs to each seah; 4 logs to each kab; the content of 6 eggs to each log. and mina (Hebrew: maneh), among others. Epiphanius, explaining the sense of certain obscure passages in the original Aramaic New Testament, writes: "The talent is called Maneh (mina) among the Hebrews," the equivalent of 100 denarii. In folios [62b–62c] Epiphanius distinguishes between "a handful" () in I Kings 17:12 and "a handful" () in Exodus 9:8 and Leviticus 16:12; in the former case it refers to only one handful, but in latter cases it refers to "a measure of two handfuls."

Part Four Geography of Palestine, Asia Minor and the Levant In folios [73b–75a] Epiphanius gives the names of several cities and places of renown, both in his time and in ancient times, such as: Mount Ararat (§ 61), Aṭaṭ (§ 62), or what is known as the "threshing floor of the thorn bush" (), and whose description echoes that of Rashi's commentary on Genesis 50:10, Abarim (§ 63); Aviʿazar (§ 68), or what is Eḇen haʿezer of I Samuel 4:1, said to be "fourteen [Roman] miles distant east and north of Eleutheropolis, in a valley"; Carmel(§ 77); Carmel of the sea (§ 78); Akko (§ 76); Anathoth (§ 66); Azekah (§ 64) - a city in whose time was called Ḥǝwarta; Bethel (§ 73); Ophrah (§ 67); Carthage (§ 79) - where the Canaanites had migrated from Phoenicia and who were called in his day Bizakanoi (scattered people); Rekem (§ 71), Jaffa (§ 75), Jerusalem(§ 74), et al.

Chronology of the Ptolemies

Ptolemy (I), also called Soter (of the Rabbit [Lagos]) = reigned 40 years Ptolemy (II) Philadelphus = reigned 38 years Ptolemy (III) the Well-Doer (Euergetes) = 24 years Ptolemy (IV) Philopator = 21 years Ptolemy (V) Epiphanes = 22 years Ptolemy (VI) Philometor = 34 years Ptolemy (VIII) the Lover of Learning and the Well-Doer = 29 years Ptolemy the Savior (Soter) = 15 years Ptolemy (X) who is also Alexas = 12 years Ptolemy (IX) the brother of Alexas = 8 years Ptolemy (XII) Dionysius = 31 years Cleopatra, the daughter of Ptolemy = 32 years

Chronology of the Roman emperors

Augustus = reigned 56 years, 6 months Tiberius = reigned 23 years Gaius = 3 years, 9 months, 29 days Claudius = 13 years, 1 month, 28 days Nero = 13 years, 7 months, 27 days Galba = 7 months, 26 days Otho = 3 months, 5 days Vitellius = reign: 8 months, 12 days Vespasian = reign: 9 years, 7 months, 12 days Titus = reign: 2 years, 2 months, 2 days Domitian = reign: 15 years, 5 months Nerva = reign: 1 year, 4 months Trajan = reign: 19 years Hadrian = reign: 21 years Antoninus, surnamed Pius = reign: 22 years Marcus Aurelius Antoninus ("otherwise known as Verus", also "called Commodus Lucius") = reign: 19 years. Of these years, 7 years he ruled jointly with Lucius Aurelius Commodus Commodus II = reign: 13 years Pertinax = 6 months Severus (reigned jointly with his son, Antoninus) = reign: 18 years Caracalla, also called Geta, who is also Antoninus = reign: 7 years (ruled jointly with Lucius Aurelius Commodus) Macrinus = 1 year Antoninus II = 4 years Alexander, the son of Mammaea = reign: 13 years Maximian = 3 years Gordian = 6 years Philip = 7 years Decius = 1 year, 3 months Gallienus (Gallus), who ruled jointly with Volusianus = 2 years, 4 months Valerian, who ruled jointly with Gallienus, also known as Gallus = 12 years Claudius = 1 year, 9 months Aurelian = 5 years, 6 months Tacitus = 6 months Probus = 6 years, 4 months Carus, who ruled jointly with his sons, Carinus and Numerian = 2 years Diocletian, who ruled jointly with Maximian, Constantine and Maxentius = 20 years Maximian (Galerius), Licinius and Constantine, who ruled in succession one after the other = 32 years Constans, Constantine and Constantius, followed by Julian, Jovian, Valentinian the Great, Valens, Gratian the son of Valentinian, Valentinian the younger (son of Valentinian), Theodosius, Arcadius the son of Theodosius, Honorius the Illustrious, who was the son of Theodosius, as far as the time of Epiphanius, during the second consulship of Arcadius Augustus and Rufus [year 392] . Years collected altogether: 57 years.

The regnal years of the Caesars as stated by Epiphanius differ slightly in some places from the extant Greek sources. With respect to events in Rome after the reign of Pertinax, both Epiphanius and Jerome do not mention the ascension of Didius Julianus after the assassination of Pertinax, but write only that Severus succeeded him.Cf. Chronicon of Jerome, 2005 online edition (tertullian.org), year 193. Epiphanius, by his own admittance (On Weights and Measures, p. 66 [folio 71c]), was familiar with Eusebius' Chronicle from which Jerome had based his Chronicon and may have used it to construct his own chronologies. This may have been because they did not consider his 9-week reign, which he obtained through usurpation, to be legitimate. Similarly, Epiphanius does not mention the ascension of Aemilian. It can be adduced from Jerome's Chronicon that Aemilian, who "caused a revolt in Moesia," was never officially confirmed by the Senate in Rome.Chronicon of Jerome, 2005 online edition (tertullian.org), year 254 Epiphanius' method of recording the regnal years from Augustus to Hadrian, with his pinpoint recollection of the number of months and days to each reign, can be said to be accurate, based on Josephus' own testimony about himself, saying that he was aged 56 in the 13th year of the reign of Caesar Domitian,Josephus, Antiquities (20.11.3) and that he (Josephus) was born in the 1st year of Caesar Gaius.Josephus, Vita § 1 Using Epiphanius' chronology for the later empire, the years are collected as 56. By comparison, the span of years in Suetonius' De vita Caesarum (Lives of the Caesars), which gives 14 years for Claudius and 15 years for Nero, the same time frame would span a period of some 58 years.Suetonius, Lives of the Caesars (the Loeb Classical Library series), vol. ii, book v, paragraph xlv

See also