History of
Sciences in the Islamic World

I. Medical
Science

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.

END

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.