History of
Sciences in the Islamic World
Medical
Science
Hospitals
Pharmacology
Industry
Geography
Chemistry
Mathematics
Art
Mechanical Engineering
MISCELLANEOUS
CONCLUSIONS
Reference
Dr. Meyerhof writes in "The
Legacy of Islam" (P.132): "Muslim doctors laughed at the Crusaders' medical
attendants for their clumsy and elementary efforts. The Europeans had not the advantage of
the books of Avicenna, Jaber, Hassan bin Haytham, Rhazes. However, they finally had them
translated into Latin. These translations exist still, without the translators' names. In
the 16th century the books of Averroes (Inb Rushd) and avicenna (Ibn Sina) were put out in
Latin translation in Italy and used as the basis of instruction in the Italian and French
universities."
On page 116 of the same work he
writes that after Rhazes' death the works of Avicenna (AD 980-1037) were taken up. His
influence on thought and philosophy and general science was profound, and his medical
works (based on the works of Galen which he had found in the Samarqand library in Arabic
translation) had a sensational outrech.
Other scientists followed -
Abu'l-Qais of Andalusia; Ibn-Zahr of Andalusia; Abbas the Irani; Ali ibn-Rezvan of Egypt;
Ibn Butlan of Baghdad; Abu Mansur Muwaffaq of Herat; Ibbn Wafeed of Spain; Masooya o
Baghdad; Ali-ibn-Esau of Baghdad; Ammar of Mosul; Ibn-Rushd (Averroes) of Andalusia; whose
works were translated into Latin were used in European universities. Europe knew nothing
of the cholera bacterium when Islam entered Spain, and the people there regarded the
disease as a punishment sent from heaven to exact the penalty of the sins: but Muslim
physicians had already proved that even the public plague was a contagious disease and
nothing else.
Dr. Meyerhof writes of Avicenna's
book "The Canon" that it is a masterpiece of medical science which proved its
vworth by being printed in a series of 16 editions in the closing years of the 15th
century AD, 15 Latin and one Arabic. In the 16th century more than a score of further
editions were published, because of its value as a scientific work. Its use continued
throughout the 17th and 18th centuries, so that it became the most widely known of all
medical treatises. It is still consulted in medical schools.
Will Durant writes that Mohammad
ibn Zachariah Razi (Rhazes) was one of Islam's most progress physicians, author of 200
treatises and books well worth studying today: in particular his
1. "Smallpox and
Measles" (published in Latin and other European tounges in 40 editions between 1497
and 1866), and
2. "The Great
Encyclopedia" 20 volumes mostly unobtainable nowadays: five volumes were devoted to
optics; translated into Latin AD 1279; printed in five editions in 1542 alone; known as
the most authoritative work on the eye and its ailments and treatment for centuries; one
of the nine basic works on which Paris University composed its medical course in 1394 AD.
Surgery made similar progress in
the hands of Islamic practitioners, who even used anaesthetics, though theses are assumed
to be of modern origin. They employed a henbane base.
Among Rhazes' innovations was the
use of cold water to treat persistent fever, of dry-cupping for apoplexy, of mercury
ointment and animal gut for wound sutures, and many others.
Further information on Islamic
medicine can be sought from the many books on the subject. The diagnosis of tuberculosis
from the fingernails, the cure of jundice, the use of cold water to prevent haemorrage,
the crushing of stones in bladder and kidney to facilitate their removal, and surgery for
hernia are among advances too numerous to mention in detail. The greatest of the Islamic
surgeons was Abu'l Qasem of Andalusia, affectionately called Abu'l-Qays, and sometimes
Abu'l-Qasees, flourit 11th century AD, inventor of very many surgical instruments and
author of books to describe them and their uses -books translated and printed in
innumerable editions in Latin and used all over Europe, the last such edition being in
1816.
Georgi Zeidan writes:
"Within two centuries of the death of the Prophet, Mecca, Medina and and other great
Muslim cities all had hospitals, while the Abbasid governors and their ministers competed
each for his own region to have the best such institution for the care of the sick.
Baghdad alone had four important hospitals. By three centuries after the hijra the
governor Adhud-ud-Dowleh Deylamy had founded the Adhudi Hospital with 24 specialists, each
master of his own particular field, a hospital which soon earned the reputation of
excelling all hospitals throughout Islam, though in the course of time it too was
surpassed.
The order and arrangement of
Islamic hospitals was such that no distinctions of race, religion or occupation were
recognised, but cure was administered with meticulous care to any patient. Separate wards
were allotted for patients of specific diseases. These were teaching hospitals where the
students learned theory and observed practice. In addition, There were travelling
hospitals which carried doctors and their gear by camel or mule to every district. Sultan
Mahmoud the Seljuk travelled with a hospital which required 40 camels for its
transport."
Dr. Gustave le Bon writes:
"Muslim hospitals went in for preventive medicine and the preservation of health as
much as if not more than for the cure of the already diseased. They were well-aired and
had plenty of running water. Muhammad bin Zachariah Razi (Razes) was ordered by the Sultan
to seek out the healthiest place in the Baghdad neighbourhood for the construction of a
new hospital. He visited every section of the town and its environs, and hung up a piece
of meat which he left while he looked into infectious diseases in the neighbourhood and
studied climatic conditions, particularly the state of the water. He balanced all these
various experimental tests and finally found them all to indicate that the place where the
portion of meat was the last to putrefy and develop infectious bacteria was the spot on
which to build. These hospitals had large common wards and also private wards for
individuals. Pupils were trained in diagnosis and brought obserrvation and experience to
the perfecting of their studies. There were also special mental hospitals, and pharmacies
which dispensed prescriptions gratis."
Marc Kapp writes: "Cairo had
a huge hospital with playing fountains and flower-decked gardens and 40 large courtyards.
Every unfortunate patient was kindly received, and after his cure sent home with five gold
coins. While Cordoba, besides its 600 mosques and 900 hammams, had 50 hospitals."
[Pharmacology, as many other
branches of sciences, is considered by Europeans to be an entirely new scientific field.
In this respect, they feel, like ancient tribes, that the world is limited to the horisons
of their territory. One must realize that this knowledge has mainly originated from the
Middle East as well as from China].
[In Europe, until recently,]
there was a surprising reluctance to apply anything resembling scientific principles to
therapeutics. Even Robert Boyle, who laid the scientific foundations of chemistry in the
middle of the seventeenth century, was content, when dealing with therapeutics (A
Collection of Choice Remedies, 1692), to describe and recommend a hotch-potch of messes
consisting of worms, dung, urine and the moss from a dead man's skull.
Gustave le Bon writes:
"Besides the use of cold water to treat typhoid cases - a treatment later abandoned,
though Europe is taking this Muslim invention up again in modern times after a lapse of
centuries - Muslims invented the art of mixing chemical medicaments in pills and
solutions, many of which are in use to this day, though some of them are claimed as wholly
new inventions of our present century by chemists unaware of their distinguished history.
Islam had dispensaries which filled prescriptions for patients gratis, and in part of
countries where no hospitals were reachable, physicians paid regular visits with all the
tools of their trade to look after public health."
Georgi Zeidan writes:
"Modern European pharmacologists who have studied the history of their profession
find that Muslim doctors launched many of the modern beneficial specifics centuries ago,
made a science of pharmacology and compound cures, and set up the first pharmacies on the
modern model. So that Baghdad alone had 60 chemists shops dispencing prescriptions
regularly at the charges of Caliph. Evidence of these facts can be seen in the names given
in Europe to quite a number of medicines and herbs which betray their Arabic, Indian or
Persian origin." Such are 'alcohol', 'alkaner', 'apricot', 'arsenic', to quote some
'a's alone.
The Abbasid Caliph
Haroun-al-Rashid sent Charlemagne in Aix from Baghdad a present of a clock made by his
horologists which struck a bell on the hour very hour, to the great wonder and delight of
the whole court of the newly crowned Holy Roman Emperor.
The massacre and expulsion of the
Muslims of Andalusia by the Christians carried with it the clousure of many of the great
factories that has existed under Islamic rule, and the standstill of progress that had
been made in science, crafts, arts, agriculture, and other products of civilization. Towns
began to fall into ruin because of the lack of skilled masons. Madrid dropped from 400,000
to 200,000 inhabitants: Seville, which had possessed 1,600 factories under the Muslims,
lost all but 300, and the 130,000 workers formerly employed had no more jobs, while the
census of Philip IV showed a fall of 75% in population figures.
It was the Muslims also who
brought about the substitution of cotton-wove paper for the old parchments; and it was
this invention which formed the basis for Europe's later invention of printing, using an
old Chinese technique, and so for the vast uprush of learning which came with the
Renaissance. More, since monks were starved for parchment on which to write their
religious works, they were tending more and more to scrape off priceless ancient
scientific texts from old parchments and to use them again as palimpsets. The introduction
of paper put a stop to this disastrous practice in time to save quite a number of texts
which would have otherwise been lost for ever, as, alas, too many were.
A paper manuscript of the year AD
1009 was found in the Escorial library, and claims to be the oldest hand-written book on
paper still in existence. Silk-wove paper, of course, was a Chinese invention, since silk
was native to China though rare in Europe; and the Musulman genius lay in seeing the
possibility of substituting cotton for silk, and so giving Europe a plentiful supply of a
practicable material for the reproduction of books by the monkish scribes.
Philip Hitti writes in his
"History of the Arabs" that the art of road-making was so well developed in
Islamic lands that Cordova had miles of paved road lit from the houses on each side at
night so that people walked in safety; while in London or Paris anyone who ventured out on
a rainy night sank up to his ankles in mud - and did so for seven centuries after Cordova
was paved! Oxford men then held that bathing was an idolatrous practice; while Cordovan
students revelled in luxurious public hammams!
The Arabian Nights' tales of
Sindbad the Sailor, and of his voyages to China, Japan, and the Spice Islands of
Indonesia, give quite enough evidence of the brilliance of Arabic commercial shipping and
the knowledge of meteorology and geography which was at their disposal. Small wonder that
the Faith spread through them from Morocco to Mindanao.
But, besides the SE Asian seas,
arabic sailors penetrated far down the East coast of Africa, and also up the rivers which
are channels from the Black Sea into the distant interior of Russia. The Safarname (Travel
journal) of Suleiman, a sea-captain of Seraf, the port on the Persian Gulf recently
excavated by Dr. David Stronach of the British Institute of Persian Studies, was published
at the end of the 9th century AD with accounts of his voyages to India and China. It was
translated into Latin, as giving some of the earliest first-hand knowledge of China which
ever reached Europe.
The geographer Ibn Hauqal
(floruit circa AD 975) wrote in his preface: "I have written the latitude and
longitude of the places of this earth, of all its countries, with their boundaries, and
the dominions of Islam, with acareful map of each section on which I have marked numerous
places, e.g. the cities, the kasbahs, the rivers, the lakes, the crops, the types of
agriculture, the roads, the distances between place and place, the goods for commerce and
everything else in the science of geography which can be useful to sovereigns and their
ministers and interesting to all people in general.
Abu-Reihan al-Biruni, Ibn Batuta
and Abu'l-Haussan are amongst other names in the history of the science of geography whose
worldwide travels were accompanied by meticulous observation and painstaking notes, which
are amongst the proudest achievements of science in our world to this day.
Jaber ibn Haiyan, disciple of the
sixth Imam Ja'afar-i-Sadeq, became known world-wide as "the Father of Chemistry"
and of Arab alchemy. His influence on western chemistry and alchemy was profound and
long-lasting. Some hundred of his works survive. Of him the late Sayyid Hebbat-ud-Din
Shahristani of Kadhemain, once Iraq's Minister of Education, writes: "I have seen
some 50 ancient MSS of works of Jaber all dedicated to his master Imam Ja'afar. More than
500 of his works have been put into print and are for the most part to be found among the
treasures of the National libraries of Paris and Berlin, while the savants of Europe
nickname him affectionately 'Wisdom's Professor' and attribute to him the discovery of 19
of the elements with their specific weights, etc. Jaber says all can be traced back to
simple basic particle composed of a charge of lightning (electricity) and fire, the atom,
or smallest indivisible unit of matter, very close to modern atomic science.
The blending of colouring
matters, dyeing, extraction of minerals and metals, steelmaking, tanning, were amongst
industrial techniques of which the Muslims were early masters. They produced Nitric Acid,
Sulphoric acid, Nitro-glycerin, Hydrochloric Acid, Potassium, Aqua Ammonia, Sal Ammoniac,
Silver Nitrate, Sulphoric Chloride, Potassium Nitrate, Alcohol, Alkali (both still known
by their Arabic names), Orpiment (yellow tri-sulphide of arsenic; arsenic is derived from
the Persian zar = gold, adjective zarnee = golden, Arabised with article "al" to
"al-zernee" pronounced "azzernee" and so taken into Greek where was
turned to the recognizable word "arsenikon" which means "masculine"
since the gold colour was supposed to link it with the sun, a musculine diety!): and
finally - though this does not close the list we might cite - Borax, also an Arabic word -
Booraq. Further, the arts of distilling, evaporation, sublimation, and the use of Sodium,
Carbon, Potassium Carbonate, Chloride, and Ammonium were common under the Abbasid
Caliphate.
Baron Carra de Vaux, author of
the chapter on "Astronomy and Mathematics" in "The Legacy of Islam"
(OUP 1931 pp. 376-398), points out that the word "algebra" is a Latinisation of
the Arabic term Al-jabr (= "i.e. of complicated numbers to a simpler language of
symbols)., thereby revealing the debt the world owes to the Arabs for this invention.
Furthermore the numerals that are used are "Arabic numerals" not merely in name
but also in fact. Above all Arabs' realisation of the value of the Hindu symbol for zero
laid the foundation of all our modern computerised technology. The word "zero",
like its cousin "cipher" are both attempts at transliterating the Arabic
"sefr", in order to convoy into Europethe reality and the meaning of that word
in Arabic.
De Vaux writes: "By using
ciphers the Arabs became the founders of the arithmetic of everyday life; they mada
algebra an exact science and developed it considerably; they laid the foundations of
analytical geometry; they were indisputably the founders of plane and spherical
trigonometry. The astrolabe (safeeha) was invented by the Arab Al-Zarqali (Arzachel) who
lived in Spain AD 1029-1087. The word "algorism" is a latinisation of the name
of his home province Al-Khwarizmi. The Arabs kept alive the higher intellectual life and
the study of science in a period when the Christian West was fighting desperately with
barbarism".
This is not the place to go
further into Muslim achievements in mathimatics and astronomy. Suffice it to refer once
again to the Jalali calendar of Omar Khayyam, with its formulae for exact calculation of
the timing of the earth's orbits round the sun, to which reference has been made earlier.
Cordova Mosque is one of the
finest monuments of Muslim art in Europe. Its architect and masons were local talent, who
introduced a number of novelties. The Muslims excelled at mosaic, inlay, fretwork and
applique work of all types. Marvellous doors, pulpits, and ceilings are decorated in many
of the ancient mosques all over the Muslim world with a lacelike design of mosaic, carved
invory and wood and plaster, and fitted pieces of carved wood interlocking with each other
with consummate artistry. Chased and engraved wood and ivory are everywhere. Thus the
Altar of the Church of Saint Isidore Hispalensis (archbishop of Seville in the first years
of the 7th century AD) like the carved ivory jewel-case made for Queen Isabella in the 11th
century and the carved ivory box now in the Church at Bayeux of the 12th century
(obviously some Crusader's loot from the East) inlaid with silver in chased gold, are
examples of that art which was the glory of Eastern lands. All this delicate and minute
handiwork was carried out with the crudest and roughest of tools, itself a further tribute
to the skill and artistry of the makers.
Jewel-studded boxes and cases and
caskets are to be seen in many places, though the best are on view in the museums of
Damascus and Cairo. Well said Sa'adi: "An Eastern artist may take 40 years to make
one porcelain vase: the West turns out 100 a day, all like: the comparative worth of the
two products can be easily reckoned!"
The Muslims were also past
masters of the art of carved and coloured plaster work, in a style which still subsists
though modern technologies are, alas, rendering the skill rarer all the time. Tenth
century examples, some with enamelled work also, are to be found in Andalusia. The
Alhambra has 13th century masterpieces of this work. The glitter like the later Italian
Majolica. The famous Alhambra flower-vase, 1.5 metres high, is unique in this line.
About the author
Donald R. Hill, a retired
engineer, became interested in Arabic while serving with Britain's Eighth Army in North
africa during World War II. After the war, he worked for the Iraq Pertoleum Company,
returning to England to join Imperyal Chemical Industries. He later moved to senior
positions in the subsidiaries of two U.S. petrochemical corporations, from which he
retired in 1984. He now devotes his time to Arabic studies, in which he has earned a
master's degree from Durham University and a Ph.D. from the University of London's School
of Oriental and African studies. His translation of al-Jazari's book of mechines won for
him a share of the 1974 Dexter Prize, awarded by the American Society for the History of
Technology.
Preface
The West is accustomed to seeing
its own intellectual development as having been shaped, in the main, by internal factors.
This view of history traces our heritage back from the Industrial Revolution to the
Enlightenment and Renaissance and, thence, via the monkish scribes of the Middle Ages, to
the fountainhead: Greece, Rome and the ancient empires of the Fertile Crescent.
But the picture is incomplete
because it ignores the intermediation of the civilization of Greek Christendom (or
Byzantium), Hindu India, Confucian China and Islam. Our subject here is the technology of
medieval Islam - the knowledge it preserved, the new ideas it contributed to the medieval
world and the inventions by which it anticipated later developments.
When the prophet Muhammad died in
A.D. 632, he left behind a new religion with its administrative centre at Medina and its
spiritual heart at Mecca. Within about a year of his death the rest of Arabia had joined
the Muslim fold; by 750 the Arab Empire stretched from the Pyrenees to central Asia.
Although the advent of Islam
brought immense political, religious and cultural changes, the technological traditions
were largely unaffected. In mechanical engineering the Muslims adapted the techniques of
earlier civilizations to satisfy the needs of the new society. These needs centered on a
city life more extensive than any seen since Roman times.
Baghdad's population is estimated
to have reached about 1.5 million in the 10th century, and cities such as Cordoba, Cairo
and Samarkand, although smaller, were still of considerable magnitude. Paris, by contrast,
would not number 100,000 souls for another 400 years. Feeding and clothing the inhabitants
of the Islamic world's vast urban centers placed great demands on agriculture and
distribution. These, in turn, depended on technology for supplying irrigation water to the
fields and for processing the crops into foodstuffs.
Water and water power, therefore,
will constitute our first concern. Then we shall describe water mills. Finally, we shall
turn to descriptions, most of them in a handful of treatises that have come down to us, of
water clocks, fountains and various automata, some of which might seem trivial to modern
eyes. Yet they exploit concepts, components and techniques that did not enter the
armamentarium of European engineering until the time of the Renaissance.
The most ancient water-raising
machine is the shaduf, a counterweighted lever from which a bucket is suspended into a
well or stream. It appears in illustrations from as early as 2500 B.C. in Akkadin reliefs
and is still in use today in parts of the Middle East. Other traditional water-raising
machines, introduced between the third and first centuries B.C., include the screw, or
water snail, whose invention is attributed to the great mathematician Archemides. It
consists of a helical wooden blade rotating within a barrellike wooden cylinder, a design
that could not push water up inclines greater than about 30 degrees, although 20 degrees
was more common.
Higher lift was achieved by the
noria, a large wheel driven by the velocity of the current. On the outer rim a series of
compartments are fitted in between a series of paddles that dip into the water and provide
the propulsive power. The water is scooped up by the compartments, or pots, and is
discharged into a head tank or an aqueduct at the top of the wheel. Norias could be made
quite large. The well-known whells at Hama on the river Orontes in Syria have a diameter
of about 20 meters. The noria is self-acting, and its operation thus requires the presence
of neither man nor beast. It is, however, expensive to build and maintain.
The "saqiya" is
probably the most widespread and useful of all the water-raising machines that medieval
Islam inherited and improved. It is a chain of pots driven by one or two animals by means
of a pair of gears. The animals push a drawbar through a circle, turning an axle whose
pinion meshes with a vertical gear. The gear carries a bearing for the chain of pots, or
pot garland - two ropes between which earthenware pots are suspended. The chain of pots is
optimal for raising comparatively small amounts of water from comparatively deep wells.
Other mechanisms, however, were
required to raise large quantities of water relatively small distances. The problem can be
solved by using a spiral scoop wheel, which raises water to the ground level with a high
degree of efficiency. The machine is very popular in Egypt nowadays, and engineers at a
research laboratory near Cairo have been trying to improve the shape of the scoop in order
to achieve the maximal output. Although it appears very modern in design, this is not the
case; a 12th-century miniature from Baghdad shows a spiral scoop wheel driven by two oxen.
These machines are still in use
in many oil-poor middle eastern countries, because for many purposes they are at least as
efficient as diesel-driven pumps. Moreover, they do not require imported fuels, spare
parts or labor. Vital time can therefore be saved, when the loss of even a single day's
operation of a machine can kill a crop, making reliable performance literally a matter of
life and death.
Given the importance of
water-raising devices to the economy of many Islamic societies, it is hardly surprising
that attempts were made to introduce new designs or modify existing ones. Some of the most
interesting innovations are found in one section of Ibn al-Razzaz al-Jazari's great book,
The book of knowledge of Ingenious Mechanical Devices, which was completed in Diyar Bakr
in Upper Mesopotamia in 1206 AD.
From our point of view, the most
significant aspect of these machines is the ideas and components that they embody. For
example, one of them is explicitly designed to eliminate out-of-balance loading and so
produce a smoother operation. Another incorporates a crank, the first known example of the
non-manual use of this important component. Some of these devices functioned as
curiosities.
The invention containing the most
features of relevance for the development of mechanical design, however, was intended as a
practical machine for high-lift duties: a twin cylinder, water-driven pump. A stream
turned a paddle wheel meshing with a horisontal gear wheel, which was installed above a
sump that drained into the stream. The horisontal wheel contained a slot into which a
vertical pin fitted near the perimeter of the wheel.
The turning wheel moved two
connecting rods back and forth, thus driving opposing pistons made of copper disks spaced
about six centimeters apart, the gap being packed with hemp. The pistons entered copper
cylinders, each one having a suction and delivery pipe. One piston began its suction
stroke while the other began its delivery stroke. This machine is remarkable for three
reasons: it incorporates an effective means of converting rotary into reciprocating
motion, it makes use of the double-acting principle and it is the first pump known to have
had true suction pipes.
Waterpower was clearly a
prominent concern of medieval Islamic planners. Whenever they mentioned a stream or river,
for example, they often included an estimate of how many mills it would operate. One might
say that they assessed streams for "mill powe"
WATERMILLS
The three main types of
waterwheel had all been in existence since Classical times - the horisontal wheel and two
variations of the vertical wheel. The horisontal wheel has vanes protruding from a wooden
rotor, onto which a jet of water is directed. In modern Europe the design was altered to
use water moving axially, like air flowing through a pinwheel, creating the water turbine.
Interestingly, wheels with curved blades onto which the flow was directed axially are
described in an Arabic treatise of the ninth century.
The more powerful vertical wheels
came in two designs: undershot and overshot. The former is a paddle wheel that turns under
the impulse of the current. The overshot wheel receives water from above, often from
specially constructed channels; it thus adds the impetus of gravity to that of the
current.
When the levels of rivers fall in
the dry season, and their flow diminishes, undershot wheels lose some of their power.
Indeed, if they are fixed to the banks of rivers, their paddles may cease to be immersed.
One way this problem was avoided by mounting the waterwheels on the piers of bridges and
taking advantage of the increased flow there. Another common solution was provided by the
shipmill, powered by undershot wheels mounted on the sides of ships moored in midstream.
On the rivers Tigris and Euphrates in the 10th century, in Upper Mesopotamia, which was
the granary for Baghdad, enormous shipmills made of teak and iron could produce 10 tons of
flour from corn in every 24-hour period.
Gristmilling - the grinding of
corn and other seeds to produce meal - was always the most important function of mills.
Mills were, however, put to many other industrial uses. Among these applications were the
fulling of cloth, the crushing of mettalic ores prior to the extraction process, rice
husking, paper making and the pulping of sugarcane. The usual method of adapting
waterwheels for such purposes was to extend the axle and fit cams to it. The cams caused
trip-hammers to be raised and then released to fall on the material.
WINDMILLS
Where waterpower was scarce, the
Muslims had recourse to the wind. Indeed it was in riverless Seistan, now in the western
part of Afghanistan, that windmills were invented, probably early in the seventh century
A.D. The mills were supported on substructures built for the purpose or on the towers of
castles or the tops of hills. They consisted of an upper chamber for the millstones and a
lower one for the rotor. A vertical axle carried either 12 or six rotor blades, each
covered with a double skin of fabric. Funnel-shaped ducts pierced the walls of the lower
chamber, their narrower ends facing toward the interior in order to increase the speed of
the wind when it flowed against the sails.
This type of windmill spread
throughout the Islamic world and thence China and India. In medieval Egypt it was used in
the sugarcane industry, but its main application was to gristmilling.
FINE TECHNOLOGY
Now we turn to a type of
engineering that is quite different from the utilitarian technology described so far. We
may perhaps call it fine technology, since its distinguishing features derive from the use
of delicate mechanisms and controls.
Some of these devices had obvious
practical uses: water clocks were used in astronomical observations and were also erected
in public places; astronomical instruments aided both observation and computation. Other
gave amusement and aesthetic pleasure to the members of courtly circles. Still others
undoubtedly had didactic purposes, for example, to demonstrate the principles of
pneumatics as understood at the time. Apart from astronomical instruments and the remains
of two large water clocks in Fez, Morocco, none of theses machines has survived. Our
knowledge of them comes almost entirely from two of Arabic treatises that have come down
to us.
The first is by the Bano (Arabic
for sons of) Musa, three brothers who lived in Baghdad in the ninth century. They were
patrons of scholars and translators as well as eminent scientists and engineers in their
own right. They undertook public works and geodetic surveys and wrote a number of books on
mathematical and scientific subjects, only three of which have survived.
The one that concerns us here is
"The Book of Ingenious Devices". It contains descriptions, each with an
illustration, of 100 devices, some 80 of which are trick vessels of various kinds. There
are also fountains that change shape at intervals, a "hurricane" lamp,
self-trimming and self-feeding lamps, a gas mask for use in polluted wells and a grab for
recovering objects from the beds of streams. This last is of exactly the same construction
as a modern clamshell grab.
The trick vessels have a variety
of different effects. For example, a single outlet pipe in a vessel might pour out first
wine, then water and finally a mixture of the two. Although it cannot be claimed that the
results are important, the means by which they were obtained are of great significance for
the history of engineering. The Banu Musa were masters in the exploitation of small
variations in aerostatic and hydrostatic pressures and in using conical valves as
"in-line" components in flow systems, the first known use of conical valves as
automatic controllers.
In several of these vessels, one
can withdraw small quantities of liquid repeatedly, but if one withdraws a large quantity,
no further extractions are possible. In modern terms, one would call the method used to
achieve this result a fail-safe system.
The second major treatise to have
come down to modern times was written by al-Jazari at the close of the 12th century. He
was a servant of the Artuqid princes, vasals of Saladin (who vanquished Richard the Lion
Heart during the Third Crusade). His work places him in the front rank of mechanical
engineers from any cultural region in pre-Renaissance times.
Several of al-Jazary's machines
have been reconstructed by modern craftsmen working from his specifications, which
provided far more detail than was customary in the days before patent law was invented.
Such openness has rarely been encountered until recent times.
WATER CLOCKS
Al-Jazari's clocks all employed
automata to mark the passage of the hours. These included birds that discharged pellets
from their beaks onto cymblas , doors that opened to reveal the figures of humans,
rotating Zodiac circles, the figures of musicians who struck drums or played trumpets and
so on. Generally speaking, the prime movers transmitted power to these automata by means
of pulley systems and tripping mechanisms. In the largest of the water clocks, which had a
working face of about 11 feet high by 4.5 feet wide, the drive came from the steady
descent of a heavy float in a circular reservoir.
Clearly, some means of
maintaining a constant outflow from the reservoir was needed and was indeed achieved in a
most remarkable way. Apipe made of cast bronze led out from the bottom of the tap, and its
end was bent down at right angles and formed into the seat of a conical valve. Directly
below this outlet sat a small cylindrical vessel in which there bobbed a float with the
valve plug on its upper surface.
When the tap opened, water ran
into the float chamber, the float rose and caused a plug to enter the valve's seat. Water
was thus discharged from a pipe at the bottom of the float chamber, and the valve opened
momentarily, whereupon water entered from the reservoir, the valve closed momentarily and
so on. An almost constant head was therefore maintained in the float chamber by feedback
control, and the large float in the reservoir descended at constant speed. Al-Jazari said
he got the idea for his invention from a simpler version which he attributed to
Archimedes.
This clock did not record equal hours of 60 minutes each, but temporal hours, that is to
say, the hours of daylight or darkness were divided by 12 to give hours that varied with
the seasons. This measurement required another piece of equipment: the pipe from the float
chamber leading into a flow regulator, a device that allowed the orifice to be turned
through a complete circle and thus to vary the static head below the surface of the water
in the reservoir. Previous flow regulators had all been inaccurate , but al-Jazari
describes how he calibrated the instrument accurately by painstaking tial-and-error
methods. Another type of clock, which may have been al-Jazari's own invention,
incorporates a closed-loop system: the clock worked as long as it was kept loaded with
metal balls with which to strike a gong.
CANDLE CLOCKS
Al-Jazari also describes candle
clocks, which all worked on a similar principle. Each design specified a large candle of
uniform cross section and known weight (they even laid down the weight of the wick). The
candle was installed inside a metal sheath, to which a cap was fitted. The cap was made
absolutely flat by turning it on a lathe; it had a hole in the centre, around which, on
the upper side, was an indentation.
The candle, whose rate of burning
was known, bore against the underside of the cap, and its wick passed through the hole.
Wax collected in the indentation and could be removed periodically so that it did not
interfere with steady burning. The bottom of the candle rested in a shallow dish that had
a ring on its side connected through pulleys to a counterweight. As the candle burned
away, the weight pushed it upward at a constant speed. The automata were operated from the
dish at the bottom of the candle. No other candle clocks of this sophistication are known.
Other chapters of al-Jazari's
work describe fountains and musical automata, which are of interest mainly because in them
the flow of water alternated from one large tank to another at hourly or half-hourly
intervals. Several ingenious devices for hydraulic switching were used to achieve this
operation. Mechanical controls are also described in chapters dealing with a potpourri of
devices, including a large metal door, a combination lock and a lock with four bolts.
We see for the first time in
al-Jazari's work several concepts important for both design and construction: the
lamination of timber to minimize warping, the static balancing of wheels, the use of
wooden templates (a kind of pattern), the use of paper models to establish designs, the
calibration of orifices, the grinding of the seats and plugs of valves together with emery
powder to obtain a watertight fit, and the casting of metals in closed mold boxes with
sand.
Previously how Islamic mechanical
technology entered Europe is unknown. Indeed, there may be instances of ideas being
inherited directly from the Greco-Roman tradition into medieval Europe. Nor can we rule
out cases of reinvention. When allowances have been made, however, it seems probable that
some elements of the rich vein of Islamic mechanical engineering were transmitted to
Europe.
Any such technological borrowing
would probably have been mediated by contacts between craftsmen, by the inspection of
existing machines working or in disrepair and by the reports of travelers. The most likely
location for the transfer of information was Iberia during the long years in which
Christians and Muslims coexisted.
The diffusion of the elements of machine technology from lands of Islam to Europe may
always remain partly conjectural. This should not in any way be allowed to devalue the
achievements of the Muslim engineers, known and anonymous. Nor should we overemphasize the
relevance of the Islamic inventions to modern machinery. Of equal or great importance is
the contribution they made to the material wealth, and hence the cultural riches, of the
medieval Near East.
END
Back to
Index of Articles
D.R. Hill (1991) Mechanical Engineering in the
Medieval Near
East. Scientific American, May: 64-69.
S.M.R. Musawi Lari (1977) Western Civilisation
Throughout
Muslim Eyes (Translated by: F.J. Goulding), Publisher: The Author, Qum (Iran).
H.P. Rang & M.M. Dale (1993) Pharmacology
(2nd ed.),
Churchill Livingstone, Edinbburgh, p 3.
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