John Greaves (1602 - October 8, 1652) was the
second Savilian Professor of Astronomy at
Oxford University from 1643 to 1649.
He was a scholar of many languages (including
ancient Greek, Arabic, Persian, and
oriental languages, which he later applied to
his study of ancient astronomy. He is well
known as being the co-editor and translator
of the Canicularia a compilation of
Arabic astronomical tables, which included
the Zij-i-Gurgani of Ulugh Beg. He
is also well-known for his studies of ancient
units of measurement, as well as his analysis
of the pyramids of ancient Egypt
published in his Pyramidographia. His
own astronomical work included early measurements
of the solar diameter.
Greaves was born in Colemore parish, Hampshire,
in the south of England. He was the eldest son
of Reverend John Greaves, and a
Laudian. As a student, he studied
classics and oriental languages at
Balliol College, Oxford, from 1617 to 1621.
He was appointed to a professorship of
Geometry at Gresham College, London, a
college which served (and still serves) to present
free lectures on academic subjects to the people of
London. However, he left this post (apparently
without leave!) in 1637 to travel to Rome with
the goal of studying ancient units of measurement
by measuring the dimensions of ancient monuments.
This work included measurements of Roman, Greek,
and Egyptian archaeological sites,
including the pyramids. He published at least two
books on this subject, including his two best-known,
Pyramidographia, or, A description of the
pyramids in Ægypt in 1646, and
A Discourse of the Roman foot and Denarius:
from whence, as from two principles, the measures,
and weights, used by the ancients, may be deduced
in 1647. The former work was criticized,
primarily because his measurements of the pyramids'
dimensions were incorrect -- the bases of the
pyramids were covered by several thousand years
worth of sand and debris. However, the latter work
was highly praised by other contemporary scholars
In 1643, Greaves was appointed to the Savilian
Chair of Astronomy at Oxford, a position which
required him to teach students the contents and
theory behind Ptolemy's
Almagest, along with more recent (primarily Arabic)
revisions to it. During his time as the Savilian
Professor, he worked to translate many works of
Arabic and Persian astronomy and astrometry to
Latin, as had his predecessor, John Bainbridge.
He released several books on the subject, including
the tables of the great astronomer of Samarkand,
Ulugh Beg, and Abu al-Fida' Isma'il ibn 'Ali.
Such works were very valuable to astronomy at the
time, as accurate, ancient records of stellar
positions and planetary motions helped later
astronomers to understand the motions of stars
and planets. For example, Greaves' translation of
Shah Cholgii Persae Astronomica (presumably
the translations of observations of a Shah(*) of
Persia) were used by John Flamsteed for his
Gresham Lectures, specifically Lecture 10 on the
obliquity of the solar ecliptic. Greaves'
work culminated with the publication of
Canicularia(**) in 1648, a large work
including translations of Arabic and Persian
astronomical tables, and derivations of
stellar positions and the Earth's precession, a
work commenced by John Bainbridge.
Unfortunately, Greaves' time as Savilian Chair
was short -- he was essentially sacked in 1649.
One reference says this was due to his
misappropriation of funds from the school.
However, as Greaves was a Laudian, and since
Charles I was executed that year, his removal
was probably due to a purge of academia
by the Cromwellians in
Apparently, Greaves knew he would be let go,
and rather than be fired, he resigned his Chair
and offered it to Seth Ward, who then held the
Savilian Chair until 1661, when Christopher Wren
In any case, Greaves remained in London, married,
and wrote several more books on astronomy,
ancient architecture, and ancient Persian grammar
before his death in 1652.
(*) Gritchka suggests "Shah Cholgius" might be
Il-Khan Hülegü, grandson of Genghis Khan.
(**) specifically, Iohannis Bainbrigii --
Canicularia: Una cum demonstratione ortus Sirii
heliaci, pro parallelo inferioris Ægypti /
Auctore Iohanne Gravio. Quibus accesserunt,
insigniorum aliquot stellar longitudines, &
latitudines, ex astronomicis observationibus Ulug
Beigi, Tamerlani Magni nepotis (nunc primum a J.
In English, it's something like Concerning
the Dog Star: one with a demonstration of
the heliacal position of Sirius from lower
Egypt. With stellar longitudes
and latitudes from astronomical
observations of Ulugh Beg, grandson of
Tamerlane. Thanks again to Gritchka
for helping to translate this ridiculously long
Francis R. Johnson, Astronomical Thought In Renaissance England, Octagon Books, NY, 1968
The Gresham Lectures of John Flamsteed, edited by Eric Forbes, Mansell
Yale University library catalog