Ibnu Yunus (977-1003)
Sebagai bentuk pengakuan dunia astronomi terhadap kiprahnya,
namanya diabadikan pada sebuah kawah di permukaan bulan. Salah satu kawah di
permukaan bulan ada yang dinamakan Ibn Yunus. Ia menghabiskan masa hidupnya
selama 30 tahun dari 977-1003 M untuk memperhatikan benda-benda di angkasa.
Dengan menggunakan astrolabe yang besar, hingga berdiameter 1,4 meter, Ibnu
Yunus telah membuat lebih dari 10 ribu catatan mengenai kedudukan matahari
sepanjang tahun.
Abu al-Hasan 'Ali ibn 'Abd al-Rahman ibn Ahmad ibn Yunus al-Sadafi
al-Misri (Arabic: ابن
يونس) (c. 950-1009) was
an important Egyptian Muslim astronomer and mathematician,[1][2][3][4] whose
works are noted for being ahead of their time, having been based on meticulous
calculations and attention to detail.
The crater Ibn Yunus on the Moon is named after him.
Information regarding his early life and education is
uncertain. He was born in Egypt between 950 and 952 and came from a respected
family in Fustat. His father was a historian, biographer and scholar of hadith,
who wrote two volumes about the history of Egypt—one about the Egyptians and
one based on traveler commentary on Egypt.[5] A prolific writer, Ibn Yunus'
father has been described as "Egypt's most celebrated early historian and
first known compiler of a biographical dictionary devoted exclusively to
Egyptians".[6] His great grandfather had been an associate of the noted
legal scholar Imam Shafi.
Early in the life of Ibn Yunus, the Fatimid dynasty came to
power and the new city of Cairo was founded. In Cairo, he worked as an
astronomer for the Fatimid dynasty for twenty-six years, first for the Caliph
al-Aziz and then for al-Hakim. Ibn Yunus dedicated his most famous astronomical
work, al-Zij al-Kabir al-Hakimi, to the latter.
As well as for his mathematics, Ibn Yunus was also known as
an eccentric and a poet.[7]
Astrology[edit]
In astrology, noted for making predictions and having
written the Kitab bulugh al-umniyya ("On the Attainment of Desire"),
a work concerning the heliacal risings of Sirius, and on predictions concerning
what day of the week the Coptic year will start on.
Astronomy[edit]
Ibn Yunus' most famous work in Islamic astronomy, al-Zij
al-Kabir al-Hakimi (c. 1000), was a handbook of astronomical tables which
contained very accurate observations, many of which may have been obtained with
very large astronomical instruments. According to N. M. Swerdlow, the Zij
al-Kabir al-Hakimi is "a work of outstanding originality of which just
over half survives".[8]
Yunus expressed the solutions in his zij without
mathematical symbols,[9] but Delambre noted in his 1819 translation of the
Hakemite tables that two of Ibn Yunus' methods for determining the time from
solar or stellar altitude were equivalent to the trigonometric identity [10]
identified in Johannes Werner's 16th-century manuscript on conic sections. Now
recognized as one of Werner's formulas, it was essential for the development of
prosthaphaeresis and logarithms decades later.
Ibn Yunus described 40 planetary conjunctions and 30 lunar
eclipses. For example, he accurately describes the planetary conjunction that
occurred in the year 1000 as follows:
A conjunction of Venus and Mercury in Gemini, observed in
the western sky: The two planets were in conjunction after sunset on the night
[of Sunday 19 May 1000]. The time was approximately eight equinoctial hours
after midday on Sunday ... . Mercury was north of Venus and their latitude
difference was a third of a degree.[11]
Modern knowledge of the positions of the planets confirms
that his description and his calculation of the distance being one third of a
degree is exactly correct. Ibn Yunus's observations on conjunctions and
eclipses were used in Richard Dunthorne and Simon Newcombs' respective
calculations of the secular acceleration of the moon.[11][12]
Pendulum
Recent encyclopaedias[13] and popular accounts[14] continue
to repeat the claim that the tenth century astronomer Ibn Yunus used a pendulum
for time measurement, despite the fact that it has been known for nearly a
hundred years that this is based on nothing more than an error made in 1684 by
the Savilian Professor of Astronomy at Oxford and Arabist Edward Bernard.[15]
Ibn
Yunus and The Pendulum: A History of Errors
In
this article, Professor David A. King explores the authenticity of the
statement that tenth-century Egyptian astronomer Ibn Yūnus was the first person
to use a pendulum to measure time. After examining evidence originating from
medieval sources along with a series of statements made by historians and
orientalists, Professor David A. King challenges common misconceptions and reveals
that the association of the pendulum with Ibn Yūnus is a history of errors.
This revelation by no means lessens
the scientific contribution of Ibn Yūnus, who was perhaps the greatest
astronomer in Islamic history. In 1970, whilst preparing his doctoral
dissertation on the astronomical handbook of Ibn Yūnus, the Hākimī Zīj, Prof. King discovered the corpus of 200 pages of tables
for astronomical timekeeping by the sun and regulating the times of Muslim
prayer for Cairo associated with the Egyptian astronomer; these were described
in a study published in 1973. In Professor King’s Magnum Opus, entitled In Synchrony with the Heavens and published in
2004, he describes dozens of such tables for different localities all over the
Islamic world, based on hundreds of previously unstudied medieval manuscripts.
Ibn Yūnus was largely responsible for this remarkable development in Islamic
astronomy.
[Note of the Editing Manager] This article was originally published as: David A.
King, "Ibn Yūnus and the Pendulum: A History of Errors” in "Archives
Internationales D'Histoire Des Sciences, vol. 29, no. 104 (1979)". We are
grateful to Professor David King for permitting republishing on the Muslim Heritage website.
Some images added as indicated in their captions.***
In the popular
literature on Islamic science one often meets the statement that the
tenth-century Egyptian astronomer Ibn Yūnus was the first person to use a
pendulum to measure time. The purpose of this note is firstly to state that
there is no evidence whatsoever in the known medieval sources that Ibn Yūnus
used a pendulum, and secondly to document a series of statements by historians
and orientalists that have led to this association of the pendulum with Ibn
Yūnus[[1]].
The
distinguished German historian of Islamic science Eilhard Wiedemann made two
separate attempts in 1919 and 1922 to kill the myth, but, judging by the
frequency of its recurrence in the modern literature, he was unsuccessful[[2]].
Wiedemann pointed out that drawings of plumb-lines in Islamic sources might
have led to the idea that Muslim scholars were already acquainted with the
pendulum. I doubt that this was the case, because such plumb-lines are
illustrated only in sections of Islamic treatises on levelling. Plates I and II
show two such illustrations, taken respectively from the treatise on
theoretical astronomy entitledNihāyat al-idrāk by the celebrated thirteenth-century
scholar Quṭb al-Dīn al-Shīrazī[[3]],
and from the treatise on the use of the Indian circle for determining the
meridian by the late-sixteenth-century writer al-Khalkhāli[[4]].
These plumb-lines need concern us no further in the present study: they have
been adequately discussed by Wiedemann. As presented in the Islamic treatises,
they are unrelated to the pendulum as a means of reckoning time.
Wiedemann
was not familiar with the Arabic manuscripts of Ibn Yūnus’ works which survive
in various libraries in Europe and the Near East, so that he was unable to seek
the origin of the myth about Ibn Yūnus and the pendulum in the primary sources.
In the past few years I have examined several dozen manuscripts of the various
astronomical works compiled by and attributed to Ibn Yūnus[[5]].
These
include manuscripts of the remaining parts of his major work, theHākimī Zīj; fragments of other zījes which
I think are also due to him; a corpus of tables for timekeeping by the sun and
regulating the astronomically-defined times of prayer; extensive solar and
lunar equation tables; trigonometric tables with entries for each minute of
argument; an astrological treatise; and a poem on the times of prayer. In none
of these is there any mention of the measurement of time using a pendulum.
Wiedemann
located the origin of the myth in the secondary sources but did not trace its
subsequent development. Besides, some of the most fantastic claims about the
invention of the pendulum by Ibn Yūnus have been made since Wiedemann’s time. I
therefore present a series of quotations from the secondary literature on
Islamic
science to document the colorful history of this myth. In view of the diverse
nature of the source material I shall include many direct quotations, with
translations into English where necessary.
***
The
association of the pendulum with the Arabs began a few decades after the
European discovery of the use of the pendulum. In 1684 the English historian
Edward Bernard wrote a letter concerning various medieval star catalogs to the
Provost of Trinity College near Dublin[[6]],
in which he stated:
“... quam
illi sollicite temporis minutias per aquarum guttulas, immanibus Schitheris,
imo (mirabile) fill penduli vibrationibus jam pridem distinxerint et
mensurarint . . .”
Translation: “... when long ago they (the Arabs)
have distinguished and measured with the same care the divisions of time by
drops of water, and by enormous sundials, and marvellously, by the vibrations
of a hanging string.”
A more
extensive quote from Bernard’s letter is recorded in translation below. No
evidence whatsoever is presented for Bernard’s assertion, but he was an Arabist
and had familiarity with some of the Arabic manuscripts in Oxford. However, the
catalogs of the Arabic manuscripts in Oxford published in 1787 (by J. Uri) and
1821-35 (by A. Nicoll) do not mention any treatises on the pendulum. One might
speculate that Bernard would probably have left some note in any Arabic
manuscript in which he had discovered some reference to the pendulum. But, as
far as we know, he did not.
In 1804
the French historian J. F. Montucla published an account of Bernard’s statement
in his Histoire
des Mathematiques[[7]].
He wrote:
“... (M.
Edouard Bernard) nous apprend que la seule bibliothèque d’Oxford possède plus
de 400 manuscrits Arabes sur l’astronomie, et si l’on veut y ajouter ceux que
pourrait encore fournir la bibliothèque orientale de M. Herbelot, celles
d’Hottinger, du père Labbe, et divers catalogues de biblio-thèques riches en
manuscrits orientaux le nombre en parâitra très consider-able. Le même M.
Bernard, qui avait parcouru une grande partie de ces manuscrits, donne une idée
fort avantageuse de l’astronomie arabe. Je vais rapporter ses paroles mêmes,
qui sont remarquables. Plusieurs avantages, dit il, rendent recommandable
l’astronomie des Orientaux, comme la sérénité des régions où ils ont observé,
la grandeur et l’exactitude des instrumens qu’ils y ont employes, et qui sont
tels que l’on aurait de la peine a le croire; la multitude dés observateurs et
des écrivains, dix fois plus grande que chez les Grecs et les Latins; le nombre
enfin des princes puissans, qui l’ont aidée par leur protection et leur
magnificence. Une lettre ne suffit pas pour faire connaître ce que les astronomes
Arabes ont trouvé à réformer dans Ptolémée, et leurs efforts pour le corriger;
quel soin ils ont pris pour mesurer le temps par des clepsidres à eau, par
d’immenses cadrans solaires, et même, ce qui surprendra, par les vibrations du
pendule; avec quelle industrie enfin et quelle exactitude ils se sont portés
dans ces tentatives délicates, et qui font tant d’honneur l’esprit humain;
savoir, de mesurer les distances des astres et la grandeur de la terre.”
Elsewhere
in his book Montucla writes of the achievements of Ibn Yūnus, without
mentioning the pendulum[[8]].
He was aware of the observation accounts in the Leiden manuscript of the Ḥākimī Zīj.
A few
years later the French astronomer P. S. Laplace in his Précis de I’ Histoire de
I’Astronomie, published in 1821, made the same
claim as Montucla about the Arab astronomers using the pendulum but did not
mention Ibn Yūnus in this connection[[9]].
Writing of the interest of the Arab astronomers in astronomical instruments, he
stated:
“Ils
donnèrent encore une attention particulière à la mesure du temps, par des
clepsydres, par d’immenses cadrans solaires, et même par les vibrations du
pendule.”
The first
reference to the use of the pendulum specifically by Ibn. Yūnus occurs in the Course of Lectures on
Natural Philosophy and the Mechanical Arts by the English scientist Thomas Young, which was published
in 1809[[10]].
Without citing any authority whatsoever, Young wrote:
“But for
the general purposes of timekeepers, all other inventions have been almost
universally superseded by the pendulum and the balance spring, or pendulum
spring. About the year 1000, Ibn Junis, and the other Arabian astronomers were
in the habit of measuring time, during their observations, by the vibrations of
pendulums; but they never connected them with machinery. The equality of the
times occupied by theses vibrations, whether larger or smaller, was known to
Galileo in 1600, and some time before 1633, he proposed that they should be
applied to the regulation of clocks.”
Where did
Young pick up this specific reference to Ibn Yūnus? The spelling Junis might
indicate a German influence. However, I think it is more significant that Young
thought that not only Ibn Yūnus but also “the other Arabian astronomers” used
the pendulum for measuring time during observations. Given the assertion of
Bernhard that the Arabs used the pendulum to measure time, and the fact that
Ibn Yūnus was celebrated for his observations, Young put two and two together
and made five.
The first
serious studies of the unique manuscript of Ibn Yūnus’ Ḥākimī Zīj preserved in Leiden were conducted in Paris in the early
nineteenth century[[11]].
In 1804 Caussin de Perceval published the text and translation of the
introductory chapters of the zīj dealing with observation accounts. Not long thereafter J.-J.
Sedillot prepared a translation of the entire manuscript which he intended to
publish. A summary was prepared by J. B. Delambre in his Histoire de l’Astronomie au
Mayen Age published in 1820, but Sédillot’s
work on Ibn Yūnus was never published, and the fate of his own papers relating
to Ibn Yūnus is uncertain. It is significant that neither J. J. Sédillot nor
Delambre made reference to the use of the pendulum by Ibn Yūnus. Sédillot’s
work on Islamic astronomy was continued by his son L. A. Sédillot, and before
the work of the Italian Arabist C. A. Nallino and the Swiss historian of
science H. Suter at the end of the nineteenth century, the researches of
Sédillots père
et fils constituted the first serious
studies on major Islamic astronomical works which had not been transmitted to
Europe, such as those of Ibn Yūnus, al-Marrākushi, and Ulugh Beg. However, Sédillot-fils
had a tendency to get carried away with certain erroneous ideas, the most
notable and controversial example of which was the alleged discovery of the
lunar variation by the tenth-century Arab astronomer Abu l-Wafā’[[12]].
In 1844 L.
A. M. Sédillot wrote in his summary of the treatise on astronomical instruments
by the thirteenth-century astronomer Abū `Alī al-Marrākushī[[13]]:
“Connaissaient-ils
le pendule, comme l’a prétendu E. Bernard, de l’université d’Oxford? c’est ce
que nos recherches ne nous ont pas encore appris.”
Elsewhere
in the same study he wrote:
“On a
prétendu que les Arabes connaissaient le pendule; c’est une question encore en
litige, main que des recherches ultérieures pourront résoudre affirmativement.”
At this
point Sédillot refers to the passage of Bernard which we have already quoted
above. In a letter to the German historian Alexander von Humboldt published in
1853 Sédillot wrote[[14]]:
“Dès les
premiers temps de cette belle période, d’importantes corrections sont apportees
aux Tables des Grecs, dont les livres sont traduits; les instruments
nécessaires sont construits par d’habiles artistes; des observatoires s’élevent
de tous cotes: le mural, le gnomon à trou, le pendule même, sont employés.”
In his Histoire des Arabes published in Paris in 1854[[15]],
L. A. Sédillot wrote of Ibn Yūnus as “… inventeur du pendule et du gnomon à
trou …”, that is “... inventor of the pendulum and the aperture gnomon ...” and
stated as one of the achievements of the Arab scientists that “… le pendule
même était connu des Arabes …”, that is, “... even the pendulum was known to
the Arabs ...” No references are given for either of these assertions. However,
in none of the manuscripts of works associated with Ibn Yūnus is there any
mention of an aperture gnomon. Sédillot’s statement that Ibn Yūnus invented the
aperture gnomon has fortunately not been repeated, apparently because his Arab
translators did not know what a gnomon à trou was.
In `Alī Mubārak’s Arabic version of Sédillot’s work printed in Cairo in 1891/92
this first quotation was translated as[[16]]:
...ikhtara’a
l-rub’ dha l-thaqb (or thuqab) wa-bandūl al-sā`a
al-daqqāqa ... which means “... he invented the quadrant with hole(s?)
and the pendulum of the ticking clock ...” In the Arabic translation published
in Cairo in 1948 by Adel Zuaitar it is translated[[17]]:
... wa-khtara`a
Ibn Yūnus al-raqqāş wa-mayl al-sā`a al-shamsīya dha l-thaqb (or thuqab) which means “… Ibn Yūnus invented the pendulum and the
inclination of the sundial with hole(s?) ...”
Thus von
Humboldt was able to write in his universal history entitled Kosmos (English translation by E. C. Otté, 1859-61), citing Laplace,
Young, and Sédillot[[18]]:
“Amongst
the advances which science owes to the Arabs, it will be sufficient to mention
Alhazen’s work on Refraction, partly borrowed, perhaps, from Ptolemy’s Optics,
and the knowledge and first application of the pendulum as a means of measuring
time, due to the great astronomer Ebn-Junis.”
‘The French scholar Gustav Lebon, in
his La
Civilisation des Arabes,
published in Paris in 1884, was the only author in the nineteenth century to
express any scepticism about the use of the pendulum by the Muslims. He wrote[[19]]:
“Les
Arabes ne connurent que les cadrans solaires comme moyen de mesurer le temps
avec précision. Le pendule n’ayant pas encore été de leur temps appliqué aux
horloges, ces dernières ne pouvaient posséder la précision nécessaire aux
recherches astronomiques ...”
“...Le
docteur E. Bernard, d’Oxford, a soutenu que les Arabes ont découvert
l’application du pendule aux horloges; mais ses raisons ne semblent pas
suffisantes pour permettre de leur attribuer une invention aussi capitale …”
In 1919
the celebrated historian of Islamic physics E. Wiedemann published an article
entitled Über
die angebliche Verivenclung des Pendels zur Zeitmessung bei den Arabern, “On the supposed use of the pendulum for time-keeping
amongst the Arabs”[[20]].
This short article begins as follows:
“Immer von
neuem taucht die Ansicht auf, daß die Araber schon um 1000 n. Chr. das Pendel
zur Zeitmessung benutzt haben. Als einer, der es verwendet hat, wird z.B. der
größte Astronom des Orientes Ibn Junus/Junis genannt, der in Kairo die nach dem
damaligen Sultan al-Hakim benannten großen hakimitischen Tafeln verfaßte. Die
Angaben stiitzen sich wohl alle auf eine recht vage Bemerkung von Ed. Bernard,
für die schon L. Sédillot eine Nach-prüfung für wünschenswert erachtete. Ed.
Bernard rühmt bei der Besprechung von Handschriften im Merton College in Oxford
die Tätigkeit der arabischen Gelehrten and bemerkt dabei:
“quam illi
sollicite temporis minutias per aquarum guttulas, immanibus Sciotheris
(Gnomone), imo (mirabile) fill penduli vibrationibus jam pridem distinxerint et
mensurarint.”
Bei
umfangreichen Studien, die ich teils allein, teils gemeinsam mit Prof. Dr.
Hauser über arabische Uhren usw. angestellt habe, ist mir aber nie die
geringste Andeutung einer Verwendung des Pendels begegnet.”
Wiedemann
went on to point out that drawings of plumb-lines in medieval Arabic
manuscripts might have led to the notion that the Muslims were familiar with
the pendulum. He presented illustrations from three Islamic works, one
anonymous and the others by al-Khalkhālī (fl. ca. 1600) and al-Isfazārī (fl. ca. 1100).
“In einer
früheren Veröffentlichung habe ich Abbildungen von Senkeln mit-geteilt, die
meiner Ansicht nach zu der irrigen Annahme führen konnten, daß die Araber
bereits Pendel zur Zeitmessung benutzt haben. Einige andere interessante
derartige Zeichnungen von Setzwagen, die zum Nivellieren von Flächen dienen,
finden sich auf fol. 16b einer
Leidener Handschrift (Gol. 192, Nr. 1105). Sie sind enthalten in dem Werk Das
königliche Geschenk über die Astronomic von Quṭb al Din al Schîrâzî (d. 1311).
An der betreffenden Stelle handelt es sich um die Bestimmung der Meridianlinie
…”
Wiedemann
then presented a diagram copied from the manuscript of al-Shīrāzī’s work and a
translation of his instructions on the use of the plumb-line. He concluded his
short paper with these words:
"Eingefügt
sind die folgenden Figuren, von denen bei der ersten die Anbringung des Senkels
an diejenige bei einem von Ibn Jûnus beschriebenen Gnomon erinnert und bei der
das Senkel bei einiger Phantasie als ein Pendel aufgefaßt werden kann."
I
personally doubt that Sédillot confused Ibn Yūnus’ gnomon with a pendulum,
since Ibn Yūnus’ description of it occurs in the middle of a section on tests
for levelling.
Wiedemann
gave no further reference to Ibn Yūnus’ gnomon, although he discussed it
elsewhere, namely, in the article Mīzān (balance)
in the Encyclopaedia
of Islam(1st ed.)[[22]],
where he listed as one of the tests used by Muslim scholars to see whether an
object was standing vertically, the following:
“In the
side of the gnomon, a perpendicular rod, often with a cone-shaped top, Ibn
Yūnus cut out a groove which ended in a hemi-spherical cavity. In the groove a
thread is hung from the top of the gnomon with a ball shaped weight. If this
comes to rest in the hollow, the gnomon is perpendicular.”
The
reference cited for this is C. Schoy’s Die Gnomonik der Araber, the basic work on Islamic sundial theory, published in
1923, where Schoy translated the section of Ibn Yūnus’ Ḥākimi Zīj dealing with gnomons[[23]].
One method of ensuring that a gnomon is vertical is translated as follows:
“Man kann
auch in dem Gnomon selbst einen Spalt und einen Faden [unter diesem Faden ist
wohl ein Senkel zu verstehen] anbringen und erkennt mittels dieser beiden, daß
der Gnomon senkrecht steht.”
If we go
back to the text of Ibn Yūnus’ Zīj, partially extant in the precious MS Leiden
Universiteitsbibliotheek Or. 143, we find the original passage on p. 240, line
2: ... wa
qad yuj`alu fi l-shakhş nafsihi kharq wa-khatt yu`lamu bi-hā waznuhu … which translates : “... a hole and a line may be made
in/on the gnomon itself, and its alignment be known by them ...”. It is difficult
to be sure what was originally intended by Ibn Yūnus in this passage. The word kharq means “hole”, not “groove”. Schoy read khaṭṭ as khayṭ, “thread”, which may indeed have been intended.
Nowhere
does Ibn Yūnus describe the shape of the gnomon, but the above passage is of
interest to the present study because it illuminates the origin of another myth
about. Ibn Yūnus. L. A. Sédillot (fils) wrote in his notes to his translation
of the introduction of the Zīj of Ulugh Beg:[[24]]
“(Ebn
Jounis) employait déjà le gnomon à trou.”
Sédillot
refers the reader to an earlier work of his[[25]],
in which there is, however, no reference whatsoever to a gnomon à trou. Ibn Yūnus did indeed observe that the end of the shadow of
a gnomon corresponds to the lower limb of the sun rather than the center of the
sun[[26]],
but nowhere does he mention an aperture gnomon. On the other hand, as we have
seen, he does mention a gnomon with a hole in it, which would also be a gnomon à trou. We should remember that Sédillot’s father translated the
entire text of the Leiden manuscript of the Ḥākimī Zīj,
and so may have told his son that Ibn Yūnus had a gnomon à trou. But we have strayed from our main theme.
Not long
after the publication of Wiedemann’s articles the American historian of science
D. E. Smith, in his widely-read History
of Mathematics first published in 1923 and since
reprinted, repeated the myth of Ibn Yūnus’ invention of the pendulum[[27]].
He also misdated Ibn Yūnus by two centuries. Without mentioning any sources, he
wrote:
“The
pendulum clock was introduced about 1657 and seems chiefly due to Huygens. The
principle of the pendulum, properly attributed to Galileo, has been observed as
early as the 12th century by Ibn Yūnis (c.1200), and had been employed by
astronomers to estimate intervals of time elapsing during an observation, but
it had not been applied to a clock …”
In another
popular book on the history of science published in the United States in the
early twentieth century W. T. Sedgwick and H. W. Tyler stated simply that “the
Arabs employed the pendulum for time measurement, and tabulated specific
gravities of metals, etc.”, again without citing any sources[[28]].
As far as
I am aware the only other person to associate Ibn Yūnus with the pendulum in
the first fifty years of this century was H. Leon, author of a non-scholarly
article on the astrology of Ibn Yūnus published in 1931. Leon described Ibn
Yūnus as “the inventor of the pendulum and the measurement of time by its
oscillations”[[29]].
The myth
of Ibn Yūnus’ invention of the pendulum might have been forgotten for all time
had it not been for the publication of an Arabic book entitled Turāth al-`Arab al-`ilmi fi
l-riyaḍiyāt wa-l-falak (The
Scientific Heritage of the Arabs in Mathematics and Astronomy), first published
in 1941 and reprinted several times since. The author, Q. H. Tuqan, presented
an uncritical summary of earlier Western writings on Islamic science. The
quality of the books as a whole is reflected by Tuqan’s entry on Ibn Yūnus,
which translates as follows[[30]]:
“Ibn Yūnus
Inventor of the Pendulum
Many
people think that the pendulum is an invention of the famous Italian scholar
Galileo (1564-1642), and that he was the first to use it. These people would be
surprised if they were told that this is not correct, and that the credit for
the invention of the pendulum goes to a Muslim Arab scholar who lived in Egypt
and grew up by the banks of the Nile. He used the pendulum before anyone else
in striking clocks, and thus preceded Galileo in this invention by six
centuries.
We should
not dare to attribute this important invention to the Arabs if it were not for
the acceptance of it by certain foreign scholars. If we read the History of the
Arabs by the famous French scholar Sédillot we find un-equivocal evidence about
the priority of the Arabs in inventing the pendulum ... Likewise Taylor and
Sedgwick state that the Arabs used the pendulum for measuring time. From this
it is clear that the Arabs preceded Galileo in the invention of the pendulum
and in using it in striking clocks.
I do not
say that the Arabs formulated the laws governing the pendulum or that they
expressed this in mathematical terms in the form which we know now, but I do say
that they preceded Galileo in inventing and using the pendulum.
Smith says
in his History
of Mathematics that although the principle of the
pendulum was formulated by Galileo, Kamāl al-Dīn ibn Yūnus noticed it and
preceded him in knowing something about it, and that the astronomers used the
pendulum for measuring time intervals during observations …”
Enough of
this. Tuqan takes Smith’s Ibn Yūnus of circa 1200
and turns him into Kamāl al-Dīn Ibn Yūnus, the celebrated scholar of Baghdad
(died 1242),30a but still writes of him here as the Fatimid astronomer Ibn
Yūnus. However, to be on the safe side, Tuqan included the quotes about the
pendulum in his article on Kamāl al-Dīn Ibn Yūnus. My translation of the
relevant passage is as follows[[31]]:
“Kamāl
al-Dīn preceded Galileo in the knowledge of some of the laws concerning the
pendulum. Smith says [sic]: “Even thought the law of the pendulum was formulated by
Galileo, Kamāl al-Dīn b. Yūnus noticed something about it and preceded
(Galileo). Astronomers used it to calculate time intervals during
observations.”
Hence it
is clear that the Arabs knew something about the laws governing the pendulum.
Galileo came after them and after numerous experiments was able to discover its
laws, insofar as he found that the period of oscillation depended on the length
of the pendulum, and the value of the acceleration due to gravity. He
formulated this in mathematical terms in an unprecedented way which widened the
scope of its use and he derived therefrom significant information.”
Unfortunately
several writers since Tuqan have reiterated the nonsense of Ibn Yūnus’
invention of the pendulum. For example, Dr. A. Zaki, in his book Turāth al-Qāhira al-`ilmī
wa-l-fannī (Medieval Legacy of Cairo),
published in Cairo in 1969, wrote (my translation)[[32]]:
“Ibn Yūnus
preceded the Italian Galileo in the invention of the pendulum and in its use in
ticking clocks.”
Likewise
Dr. A. Muntasir in his book Ta’rikh
al-`ilm wa-dawr al-`ulemā’ al-`Arab fī taqaddumihi (The History of Science and the Role of the Arabs in its
Develop-ment), published in Cairo in 1973, wrote (my translation)[[33]]:
“It was he
(that is, Ibn Yūnus) who invented the pendulum, thus preceding Galileo by
several centuries. It (that is, the pendulum) was used to calculate time
intervals during observations, as it was used in ticking clocks.”
same
author made an even bolder claim in a chapter Theon science in a UNESCO -
sponsored volume Athar
al-`Arab wa-l-Islām fi l-nahḍa al-Ūrūbīya (The Influence of the Arabs and Islam
on the European Renaissance) (my
translation)[[34]]:
“Ibn Yūnus
invented the pendulum and the Arabs used it in their calculations and
astronomical experiments. Ibn Yūnus and Ibn Hamza take the credit for their
studies of arithmetical and geometrical series: their studies had the greatest
influence in laying the foundations on which were built differential and
integral calculus and tables of logarithms.”
At least
Ibn Yūnus wrote nothing on mathematical series. What Ibn Ḥamza (fl. Mecca, ca. 1590) wrote on series and algebraic notation was of
interest but with-out any influence on the development of mathematics in the
West[[35]].
Again, Dr.
S. Maher, in her book on navigation in medieval Egypt published in Cairo in
1968(?), wrote (my translation)[[36]]:
“Enough
glory to Ibn Yūnus that it was he who invented the pendulum and thus preceded
Glileo in this invention by six centuries (Tuqan, p. 275).”
Tuqan’s
claims for Ibn Yūnus have been repeated more recently by Dr. G. Shawqi in an
article on ideas of motion in medieval Arabic sources published in 1975.
Quoting in full from Tuqan the “evidence” of Sédillot, and Tyler and Sedgwick,
he writes (my translation)[[37]]:
“The Arab
scholar ... Ibn Yūnus . . . is considered the inventor of the pendulum. The
attribution of this invention to Ibn Yūnus ... occurred in the writings of the
equitable French orientalist Sedillot . . . Likewise two other orientalists (I)
Tyler and Sedgwick refer to the priority of the Arabs in (the invention of) the
pendulum . . . These sources show that the credit for in-venting the pendulum
and using it to calculate time intervals during observations is due to the
Arabs. Consequently it is inevitable that they were aware of the relations
pertaining to the duration of the oscillation of the pendulum, and this was
before the Italian scholar Galileo Galilei by more than six centuries."
In a book
on the Arab contribution to mechanics published just two years earlier—Shawqi
made no reference whatsoever to either Ibn Yūnus or the pendulum[[38]].
“(Ibn
Yūnus) was probably the first to study the isometric oscillatory motion of a
pendulum — an investigation which later led to the construction of mechanical
clocks.”
In his new
book, Islamic
Science: an Illustrated Study,
published in 1976 on the occasion of the Festival of the World of Islam in
London, Nasr was able to writes[[40]]:
“Ibn Yūnus
was also the first person to make a serious study of the oscillatory motion of
a pendulum, which finally led to the invention of the mechanical clock.”
He gives
no reference for the statement, and it is sad indeed to see inaccuracies of
this kind throughout a book which is likely to be widely considered as an
authoritative general work on Islamic sciences[[41]].
Whilst all
of these authors since Tuqan associate the invention of the pendulum with the
Egyptian astronomer Ibn Yūnus, the association with the Baghdad scholar Ibn
Yūnus is recorded for posterity in the article “Pendulum” by F. J. Wood in the
International Edition of the Encyclopedia
Americana[[42]],
where we read:
“The
periodic, oscillatory motion of a pendulum provides an example of the kinetic
state known in physics as simple harmonic motion. This property of a pendulum,
while known to the Arab Ibn Yûnis (ca. 1200), was rediscovered by Galileo ...”
In 1962
there appeared in a Beirut newspaper an article about the invention of the
pendulum by the scholar Kamāl al-Dīn ibn Yūnus[[43]].
I have not seen this article, but following its publication the author Usama
Anuti, then lecturer at the Lebanese University, decided to pursue the evidence
for the invention more carefully, and in 1964 published a booklet in Arabic
entitled Hal
iktashafa I-‘Arab raqqāş al-sā`a? (Did
the Arabs Discover the Pendulum?)[[44]].
The paper
consists mainly of a carefully documented account of the statements of
Sédillot, Smith, and Tuqan, and includes two citations from modern popular
works in which the discovery by Ibn Yūnus is stated as if it were a fact[[45]].
Anuti noted that three scholars who might have been expected to know something
about Ibn Yūnus, namely, Caussin de Perceval (who in 1804 published part of the
introduction to Ibn Yūnus’ major work), H. Suter (who in 1900 published a list
of over five hundred Muslim scientists and their works and all available
manuscripts), and G. Sarton (whose monumental bibliographical work on the
history of science published in 1927-48 is thought by the misinformed to be the
last word on Islamic science), all made no mention of Ibn Yūnus and the
pendulum. However, weighing the “evidence” presented by Sédillot, Smith, and
Tuqan, Anuti came to five conclusions[[46]],
of which three are relevant to the present study[[47]].
A translation follows:
“Firstly,
the Arabs participated in this scientific discovery, and they knew some of the
laws of the pendulum and they used them in the mathematical field but not in
the instrumental.
Secondly,
the credit for finding its laws goes back, apparently, to Ibn Yūnus the
Egyptian, not to (the Ibn Yūnus) from Mosul.
Fourthly,
it appears that the ancient authors of biographies attributed something due to
the Egyptian to the scholar of Mosul ...”
Anuti had
enough of the necessary modern sources at his disposal to realise that the
attribution of the discovery of the pendulum to Ibn Yūnus stood on rather
insecure foundations, but at least he sorted out the problem of Kamāl al -Dīn
Ibn Yūnus.
Anuti’s
work has, as far as I know, been cited only once in the more recent literature.
In the introduction of the photo-offset edition of the treatise on mechanical
devices by the twelfth -century engineer al-Jazari published in 1977 by the
Centre for the Revival of the Arab Scientific Heritage at the University of
Baghdad, mention is made of the discovery of the pendulum by the Arabs47a. The
editor, M. A. Shams, asserts that “the sources” state that Abū Sa`īd `Abd
al-Raḥmān ibn Yūnus al-Miṣri discovered the pendulum (hereby confusing the
astronomer ‘Alī ibn `Abd al-Raḥmān ibn Yūnus with his father, who was also
called Ibn Yūnus!) and, quoting Anuti’s second article, not his first one (!),
adds that the scholar of Mosul, Yūnus ibn Muḥammad ibn Man`a (hereby confusing
Kamāl al-Din Ibn Yūnus with his father!), also “knew many things about the laws
governing the oscillation of the pendulum.” Now we have three Ibn Yūnus’es and
one Yūnus who are associated with the discovery of the pendulum!
After the
completion of this paper Prof. Bert S. Hall of the University of Toronto showed
me the proofs of a paper of his on the early history of the pendulum in Europeo[47b]. In this
study Prof. Hall has devoted a paragraph to the false attribution of the
invention of the pendulum to Ibn Yūnus, and has refered to the origin of the
myth in the writings of Bernard, its recurrence in later European sources, and
its confutation in the two articles by Wiedemann.
***
When did
the pendulum became known in the Islamic world? We cannot do better than read
what has been written by O. Kurz in his European Clocks and Watches in the Near East, published in 1975, on this very subject[[48]]:
“Watches
were not the only line English craftsmen had to offer; pendulum clocks too
found a ready market in Turkey, although only at a slightly later date. With
the invention of the pendulum clock in the seventeenth century precise
time-keeping had at last become possible. While Europe was still discussing
this amazing new invention and arguing whether the priority belonged to Galilei
or to Huygens, somebody came forward with the surprising claim that the real
inventors of the pendulum clock were the Arabs [footnote referring toBernard]. The extraordinary idea that medieval Arabic clocks could
have been regulated by a pendulum was widely believed [foot-note referring to von Humboldt]. E. Wiedemann has shown how the misunderstanding came
about: what looked like a pendulum in the illustrations of medieval Arabic
manuscripts was in reality a plumb-line [footnote referring to Wiedemann 1 and 2].
Bringing
pendulum clocks to Turkey was not as easy as it might appear. In the year 1680,
not so long after the new invention had been made, the English ambassador to
the Sublime Porte, Sir John Finch, thought of modernizing the traditional
“gifts” by including among them a telescope and a “rare pendulum”, but as the
Grand Vizier expected a large sum of money, the gifts were refused [footnote].
In 1699 a new French ambassador arrived in Istanbul. He brought with him a
magnificent pendule with a dial marked à la turquedestined
for the Grand Vizier, and an even more magnificent one for the Sultan. But when
he was about to enter the audience chamber, the proud ambassador of Louis XIV
refused to give up his sword. The audience never took place, and the presents
were returned to the ambassador [footnote]. In spite of these initial setbacks
pendulum clocks did eventually arrive in the Saray. When a new French
ambassador arrived in Turkey in 1716, he successfully delivered at the Sublime
Porte une
magnifique pendule for the Grand
Vizier and deux
magnifiques pendules for the
Sultan himself [footnote].”
Conclusions
In order that
no confusion may arise about my own conclusions I shall summarize them as
follows:
1.
The statement that the pendulum was
used by the Arabs was first made by Edward Bernard (1684). It was repeated by
Montucla (1804) and Laplace (1821), but Thomas Young (1809) introduced the
additional fiction that Ibn Yūnus and “the other Arabian astronomers” used the
pendulum. The distinguished historian of Islamic science L. A. Sédillot
(1853-54) convinced himself that this was indeed the case. The American
historian of mathematics Eugene Smith (1923) mentioned the attribution of the
discovery to Ibn Yūnus but made a mistake about the date of Ibn Yūnus, which
enabled Qadri Tuqan (1941) to introduce Kamāl al-Dīn Ibn Yūnus into the picture
as well.
2.
No author from Bernard (1684) to
Nasr (1976) has adduced a shred of evidence to support the claim that the
pendulum was used by Ibn Yūnus or any other Muslim scholar.
References
^ Ivan van Sertima, Egypt: Child of Africa, p. 337.
^ Science & Technology in the Islamic World - Page 77
^ Science in Medieval Islam: an illustrated introduction
by Howard R. Turner - Page 65
^ Eternal Egypt. Ibn-Yunus El-Falaky.
^ Eternal Egypt. Ibn Yunus The Historian.
Jump up ^ Eickelman, Dale F. James Piscatori. Muslim
Travellers: Pilgrimage, Migration, and the Religious Imagination. Berkeley:
University of California Press, 1990. p. 58
Jump up ^ Berggren, J. L. (2003), Episodes in the
Mathematics of Medieval Islam, Springer, p. 148, ISBN 9780387406053.
Jump up ^ N. M. Swerdlow (1993), "Montucla's Legacy:
The History of the Exact Sciences", Journal of the History of Ideas 54
(2): 299-328 [320].
Jump up ^ Complete Dictionary of Scientific Biography,
2008
Jump up ^ David A. King, 'Islamic Math and Science',
Journal for the History of Astronomy, Vol. 9, p.212
^ Jump up to: a b O'Connor, John J.; Robertson, Edmund
F., "Abu'l-Hasan Ali ibn Abd al-Rahman ibn Yunus", MacTutor History
of Mathematics archive, University of St Andrews.
Jump up ^ Raymond Mercer (1994), 'English Orientalists
and Mathematical Astronomy' in The 'Arabick' Interest of the Natural
Philosophers in 17th-Century England, p.198
Jump up ^ Good, Gregory (1998). Sciences of the Earth: An
Encyclopedia of Events, People, and Phenomena. Routledge. p. 394.
ISBN 0-8153-0062-X.
"Pendulum". Encyclopedia Americana 21. The
Americana Corp. 1967. p. 502. Retrieved 2009-02-20.
Baker, Cyril Clarence Thomas (1961). Dictionary of
Mathematics. G. Newnes. p. 176.
Jump up ^ Newton, Roger G. (2004). Galileo's Pendulum:
From the Rhythm of Time to the Making of Matter. US: Harvard University Press.
p. 52. ISBN 0-674-01331-X.
Jump up ^ King, D. A. (1979). "Ibn Yunus and the
pendulum: a history of errors". Archives Internationales d'Histoire des
Sciences 29 (104): 35–52.
Hall, Bert S. (September 1978). "The scholastic pendulum".
Annals of Science (Taylor & Francis) 35 (5): 441–462.
doi:10.1080/00033797800200371. ISSN 0003-3790. Retrieved 2010-04-22.
O'Connor, J. J.; Robertson, E. F. (November 1999).
"Abu'l-Hasan Ali ibn Abd al-Rahman ibn Yunus". University of St
Andrews. Retrieved 2007-05-29.
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