ISLAMS GIFTS TO THE WORLD [Electronic resources] نسخه متنی

History of Sciences in the
Islamic World

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.

II. Hospitals

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.

III.
Pharmacology

[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.

IV.
Industry

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!

V. Geography

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.

VI. Chemistry

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.

VII.
Mathematics

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.

VIII. Art

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.

IX.
Mechanical Engineering

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.

MISCELLANEOUS

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.

CONCLUSIONS

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.

Reference:

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.