| From: Thomas Hockey et al. (eds.). The Biographical Encyclopedia of Astronomers, Springer Reference. New York: Springer, 2007, p. 538 |
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Courtesy of 
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Jacob ben Makhir ibn Tibbon
Raymond Mercier
Alternate
names
Don Profeit Tibbon
Profatius
Died circa
1305
Jacob
ben Makhir was a translator of Arabic scientific works into Hebrew and also
wrote a few original astronomical works. Known also as Don Profeit Tibbon,
he was a Jewish scholar who lived in Montpellier and other Provençal towns.
He wrote exclusively in Hebrew; his extensive output included both translations
into Hebrew and original compositions. Since he was known under two distinct
Hebrew names, modern scholars had treated these as representing two separate
persons, until Salomon Munk (Mélanges, p. 489, n. 3) showed they were
one and the same. The Hebrew word mekîr means “gain” or “profit,”
hence the Provençal form Profeit (and many variants) and the Latin Profatius.
Jacob ben Makhir's translations were almost entirely of mathematical
and astronomical works, both original Arabic tracts and Arabic versions of
Greek works. These included Euclid's Elements and Data; Autolycus'
Moving Sphere; Menelaus'
Sphere; Qusṭā ibn Lūqā's On the Spherical Astrolabe (al‐Kura
al‐falakiyya); Ibn al‐Haytham's On the Configuration of the World
(Fī hayʾat al‐ʿālam); Ibn al‐Ṣaffār's On Using the Astrolabe
(al‐ʿAmal bi‐ʾl‐asṭurlāb);
Jābir ibn Aflaḥ's Correction of the Almagest (Iṣlāḥ al‐Majisṭi);
and Zarqālī's, On the al‐ṣaf īḥa (A development of the
astrolabe plate).
Jacob
ben Makhir's two original works were on the quadrant and an “almanach.” His
Explanation of the Instrument Called the Quadrant of Israel was translated
widely into Latin, where it was referred to as Quadrans Novus; it is
found in the manuscripts with various incipits (such as quoniam scientie
astronomie non completur absque instrumentis). The work had a wide influence
from the last decade of the 13th century.
The
Almanach was known simply in Hebrew as luḥot, a term used for all
astronomical tables. This is based directly, as the author says, on a quite
similar work by Zarqālī (circa 1075), and calculated according
to the Toledan Tables, but with a change of meridian from Toledo to Montpellier.
This is not a set of tables like those found in a typical Arabic handbook
(zīj). Rather, the true tropical positions of the Sun and the
planets are given in cycles such that only small corrections are to be applied
to cycles beyond the original one. In the case of the Moon, some calculations
are required, but much less than when working directly from the tables of
a zīj. The tabulation of the Sun is given in a 4‐year cycle,
beginning 1 March 1301, while the five planets (Saturn to Mercury) begin on
10 March 1300 (outer planets), 5 March 1301 (Venus), and 5 March 1300 (Mercury);
the periods in years of the tabulations are approximately 60, 84, 80, 9, and
47 years, respectively. The tabulation of the corrected equation of the Moon
is given daily from 22 March 1300 for 23 years. In these tables the amount
of precession, which is represented by the “equation of the eighth sphere,”
has been added to the sidereal longitudes derived from the Toledan Tables,
so as to give tropical longitudes. A table of the equation of the eighth sphere
is found in manuscripts of the Almanach, but it is not included in
the edition by Boffito d'Eril. Both this work and the Almanach of Zarqālī
could be usefully examined in greater depth.
Jacob ben Makhir was influential long after his time, perhaps surprising
in view of his extant work. For example, Nicholas
Copernicus (De Revolutionibus, III, 2 and 6) attributes to
him the value 23° 32′ of the obliquity for the year 1290, although this has not been traced
to any surviving text.
Finally we should mention that Jacob ben Makhir also produced Hebrew
versions of the works of various philosophers, including Ibn
Rushd.
Selected References
Boffito,
J. and C. Melzi d'Eril (1908). Almanach Dantis Aligherii, sive Profhacii
Judaei Montispessulani Almanach perpetuum ad annum 1300 inchoatum. Florence:
Olschki.
Millás
Vallicrosa, José María (1932). “La introducción del cuadrante con cursor en
Europa.” Isis 17: 218–258. (Reprinted in Millás Vallicrosa, Estudios
sobre historia de la ciencia española. Barcelona,
1949.)
———
(1933). Tractat de l'assafea d'Azarquiel. Barcelona.
——— (1943–1950). Estudios
sobre Azarquiel. Madrid‐Granada.
Munk,
Salomon (1859). Mélanges de philosphie juive et arabe. Paris:
A. Franck.
Renan,
E. (1877). “Les rabbins français du commencement du xive siècle.” Histoire littéraire de la France 27: 599–623.
Steinschneider, Maurice (Oct. 1876). “Prophatii Judaei Montepessulani
Massiliensis (a. 1300): Proemium in Almanach.” Bulletino di bibliografia
e di storia delle scienze matematiche e fisiche 9: 595–614.
Toomer,
G. J. (1973). “Prophatius Judaeus and the Toledan Tables.” Isis 64:
351–355.