History of Technology

Heroes and Villains - A little light reading Here you will find a brief history of technology. Initially inspired by the development of batteries, it covers technology in general and includes some interesting little known, or long forgotten, facts as well as a few myths about the development of technology, the science behind it, the context in which it occurred and the deeds of the many personalities, eccentrics and charlatans involved. "Either you do the work or you get the credit" Yakov Zel'dovich - Russian Astrophysicist Fortunately it is not always true.

The Content - It's not just about batteries. Scroll down and see what treasures you can discover.

Background

We think of a battery today as a source of portable power, but it is no exaggeration to say that the battery is one of the most important inventions in the history of mankind. Volta's pile was at first a technical curiosity but this new electrochemical phenomenon very quickly opened the door to new branches of both physics and chemistry and a myriad of discoveries, inventions and applications. The electronics, computers and communications industries, power engineering and much of the chemical industry of today were founded on discoveries made possible by the battery.

Pioneers

It is often overlooked that throughout the nineteenth century, most of the electrical experimenters, inventors and engineers who made these advances possible had to make their own batteries before they could start their investigations. They did not have the benefit of cheap, off the shelf, mass produced batteries. For many years the telegraph, and later the telephone, industries were the only consumers of batteries in modest volumes and it wasn't until the twentieth century that new applications created the demand that made the battery a commodity item.

In recent years batteries have changed out of all recognition. No longer are they simple electrochemical cells. Today the cells are components in battery systems, incorporating electronics and software, power management and control systems, monitoring and protection circuits, communications interfaces and thermal management.

History of Technology from the Bronze Age to the Present Day

Circa 3000 B.C. At the end of the fourth millennium B.C. the World was starting to emerge from the Stone Age.

Around 2900 B.C., Mesopotamians (from modern day Iraq), who had already been active for hundreds of years in primitive metallurgy extracting metals such as copper from their ores, led the way into the Bronze Age when artisans in the cities of Ur and Babylon discovered the properties of bronze and began to use it in place of copper in the production of tools, weapons and armour. Bronze is a relatively hard alloy of copper and tin, better suited for the purpose than the much softer copper enabling improved durability of the weapons and the ability to hold a cutting edge. The use of bronze for tools and weapons gradually spread to the rest of the World until it was eventually superceded by the much harder iron.

Mesopotamia, incorporating Sumer, Babylonia and Assyria, known in the West as the Cradle of Civilisation was located between the Tigris and Euphrates rivers (The name means "land between the rivers") in the so called Fertile Crescent stretching from the current Gulf of Iran up to modern day Turkey. The ancient city of Babylon which served for nearly two millennia as a center of Mesopotamian civilization is located about 60 miles (100 kilometers) south of Baghdad in modern-day Iraq. (See Map of Mesopotamia).

Unfortunately this accolade ignores the contributions of the Chinese people and the Harappans of the Indus Valley, (Modern day Pakistan) who were equally "civilised" during this period practicing metallurgy (copper, bronze, lead, and tin) and urban planning, with civic buildings, baked brick houses, and water supply and drainage systems.

From around 3500 B.C. the Sumerians of ancient Mesopotamia developed the World's first written language. Called Cuneiform Writing from the Latin "cuneus", meaning "wedge", it was developed as a vehicle for commercial accounting transactions and record keeping. The writing was in the form of a series of wedge-shaped signs pressed into soft clay by means of a reed stylus to create simple pictures, or pictograms, each representing an object. The clay subsequently hardened in the Sun or was baked to form permanent tablets. By 2800 B.C. the script progressively evolved to encompass more abstract concepts as well as phonetic functions (representing sounds, just like the modern Western alphabet) enabling the recording of messages and ideas. For the first time news and ideas could be carried to distant places without having to rely on a messenger's memory and integrity.

Hieroglyphic script evolved slightly later in Egypt. Though the script appeared on vases and stone carvings, many important Egyptian historical scripts and records were written in ink, made from carbon black (soot) or red ochre mixed with gelatin and gum, applied with a reed pen onto papyrus. Produced from the freshwater papyrus reed, the papyrus scrolls were fragile and susceptible to decay from both moisture and excessive dryness and many of them have thus been lost, whereas the older, more durable clay cuneiform tablets from Mesopotamia have survived.

Historians seem to agree that the wheel and axle were invented around 3500 B.C. in Mesopotamia. Pictograms on a tablet dating from about 3200 B.C. found in a temple at Erech in Mesopotamia show a chariot with solid wooden wheels. Evidence from Ur indicates that the simpler potter's wheel probably predates the use of the axled wheel for transport because of the difficulty in designing a reliable mechanism for mounting the rotating wheel on a fixed hub or a rotating axle on the fixed load carrying platform.

Sumerian mathematics and science used a base 60 sexagesimal numeral system. 60 is divisible by 1,2,3,4,5,6,10,12,15,20,30 and 60 making it more convenient than using a base 10 decimal system when working with fractions. The Mesopotamians thus introduced the 60-minute hour, the 60-second minute and the 360-degree circle with each angular degree consisting of 60 seconds. The calendar adopted by the Sumerians, Babylonians and Assyrians was based 12 lunar months and seven-day weeks with 24-hour days. Since the average lunar month is 29.5 days, over 12 months this would produce a total of only 354 days as against a solar year of 365.25 days. To keep the calendar aligned to the seasons they added seven extra months in each period of 19 years, equivalent to the way we add an extra day in leap years. Despite decimalisation, we still use these sexagesimal measures today.

The Mesopotamians discovered glass, probably from glass beads in the slag resulting from experiments with refining metallic ores. They were also active in the development of many other technologies such as textile weaving, locks and canals, flood control, water storage and irrigation.

There are also claims that the Archimedes' Screw may have been invented in Mesopotamia and used for the water systems at the Hanging Gardens of Babylon.

2500 B.C. Sometimes known as the "Second oldest profession", soldering has been known since the Bronze Age (Circa 3000 to 1100 B.C.). A form of soldering to join sheets of gold was known to be used by the Mesopotamians in Ur. Fine metal working techniques were also developed in Egypt where filigree jewellery and cloisonné work found in Tutankhamun's tomb dating from 1327 B.C. was made from delicate wires which had been drawn through dies and then soldered in place.

Egypt was also home to Imhotep the first man of science in recorded history. He was the world's first named architect and administrator who around 2725 B.C. built the first pyramid ever constructed, the Stepped Pyramid of Saqqara. Papyri were unearthed in the nineteenth century dating from around 1600 B.C. and 1534 B.C. both of which refer to earlier works attributed to Imhotep. The first outlines surgical treatments for various wounds and diseases and the second contains 877 prescriptions and recipes for treating a variety of medical conditions making Imhotep the world's first recorded physician. Other contemporary papyri described Egyptian mathematics. Egyptian teachings provided the foundation of Greek science and although Imhotep's teachings were known to the Greeks, 2200 years after his death, they assigned the honour of Father of Medicine to Hippocrates.

2300 B.C. The earliest evidence of the art of stencilling used by the Egyptians. Designs were cut into a sheet of papyrus and pigments were applied through the apertures with a brush. The technique was reputed to have been in use in China around the same time but no artifacts remain.

2100-1600 B.C. The Xia dynasty in China perfected the casting of bronze for the production of weapons and ritual wine and food vessels, reaching new heights during the Shang dynasty (1600-1050 B.C.).

Circa 2000 B.C. The process for making wrought iron was discovered by the Hittites, in Northern Mesopotamia and Southern Anatolia (now part of Eastern Turkey), who heated iron ore in a charcoal fire and hammered the results into wrought (worked) iron. See more about wrought iron

1300 B.C. Fine wire also made by the Egyptians by beating gold sheet and cutting it into strips. Recorded in the Bible, Book of Exodus, Chapter 39, Verse 3, - "And they did beat the gold into thin plates, and cut it into wires, to work it. in the fine linen, with cunning work."

The Egyptians also made coarse glass fibres as early as 1600 B.C. and fibers survive as decorations on Egyptian pottery dating back to 1375 B.C.

1280 B.C. Around this date, after his escape from Egypt, Moses ordered the construction of the Ark of the Covenant to house the tablets of stone on which were written the original "Ten Commandments". Its construction is described in great detail in the book of Exodus and according to the Bible and Jewish legend it was endowed with miraculous powers including emitting sparks and fire and striking dead Aaron's sons and others who touched it. It was basically a wooden box of acacia wood lined with gold and also overlaid on the outside with gold. The lid was decorated with two "cherubim" with outstretched wings. In 1915 Nikola Tesla, in an essay entitled "The Fairy Tale of Electricity" promoting the appreciation of electrical developments, proposed what seemed a plausible explanation for some of the magical powers of the Ark. He claimed that the gold sheaths separated by the dry acacia wood effectively formed a large capacitor on which a static electrical charge could be built up by friction from the curtains around the Ark and this accounted for the sparks and the electrocution of Aaron's sons.

Recent calculations have shown however that the capacitance of the box would be in the order of 200 pico farads and such a capacitor would need to be charged to 100,000 volts to store even 1 joule of electrical energy, not nearly enough to cause electrocution. It seems Tesla's explanation was appropriately named.

800 B.C. The magnetic properties of the naturally occurring lodestone were first mentioned in Greek texts. Also called magnetite, lodestone is a magnetic oxide of iron (Fe 3 O 4 ) which was mined in the province of Magnesia in Thessaly from where the magnet gets its name. Lodestone was also known in China at that time where it was known as "love stone" and is in fact quite common throughout the world.

Surprisingly although they were aware of its magnetic properties, neither the Greeks nor the Romans seem to have discovered its directive property.

Eight hundred years later in 77 A.D., the somewhat unscientific Roman chronicler of science Pliny the Elder, completed his celebrated series of books entitled "Natural History". In it, he attributed the name "magnet" to the supposed discoverer of lodestone, the shepherd Magnes, "the nails of whose shoes and the tip of whose staff stuck fast in a magnetic field while he pastured his flocks". Thus another myth was born. Pliny was killed during the volcanic eruption of Mount Vesuvius near Pompeii in A.D. 79 but his "Natural History" lived on as an authority on scientific matters up to the Middle Ages.

600 B.C. The Greek philosopher and scientist, Thales of Miletus (624-546 B.C.) - one of the Seven Wise Men of Greece (Miletus is now in Turkey) - was the first thinker to attempt to explain natural phenomena by means of some underlying scientific principle rather than by attributing them to the whim of the Gods - a major departure from previous wisdom and the foundation of scientific method, frowned upon by Aristotle but rediscovered during the Renaissance and the Scientific Revolution.

He travelled to Egypt and the city state of Babylon in Mesopotamia (now modern day Iraq) and is said to have brought Babylonian mathematics back to Greece. The following rules are attributed to him:

Any angle inscribed in a semicircle is a right angle. Known as the Theorem of Thales it was however known to the Babylonians 1000 years earlier.

A circle is bisected by any diameter.

The base angles of an isosceles triangle are equal.

The opposite angles formed by two intersecting lines are equal.

Two triangles are congruent (equal shape and size) if two angles and a side are equal.

The sides of similar triangles are proportional

Using the concept of similar triangles he was able to calculate the height of pyramids by comparing the size of their shadows with smaller, similar triangles of known dimensions. Similarly he calculated the distance to ships at sea by noting the azimuth angle of the ship from a baseline of two widely spaced observation points a known distance apart on the shore and scaling up the distance to the ship from the dimensions of a smaller similar triangle. In this way he was able to calculate the distance to far off objects without measuring the distance directly, the basis of modern surveying.

Thales also demonstrated the effect of static electricity by picking up small items with an amber rod made of fossilised resin which had been rubbed with a cloth. He also noted that iron was attracted to lodestone.

Thales left no writings and knowledge of him is derived from an account in Aristotle's Metaphysics written nearly 300 years later and itself subject to numerous subsequent copies and translations.

530 B.C. Pythagoras of Samos (580-500 B.C.) an Ionian Greek, is considered by many to be the Father of Mathematics. Like Thales, he had travelled to Egypt and Babylon where he studied astronomy and geometry. His theorem. "In a right-angled triangle the square on the hypotenuse is equal to the sum of the squares on the other two sides" is well known to every schoolchild.

Around 530 BC, he moved to Croton, in Magna Graecia, where he set up a religious sect. His cult-like followers, were enthralled by numbers such as prime numbers and irrational numbers and considered their work to be secret and mystical. Prior to Pythagoras, mathematicians had dealt only in whole numbers and fractions or ratios but Pythagoras brought them into contact with √2 and other square roots which were not rational numbers.

Pythagoreans also discovered the Divine Proportion, also called the Golden Mean or Golden Ratio, an irrational number Φ (Phi) = (√5+1)/2 ≈ 1.618 which has fascinated both scientists and artists ever since.

(See examples of The Divine Proportion).

None of Pythagoras writings have survived and knowledge of his life and works is based on tradition rather than verified facts.

Circa 500 B.C. Cast iron was produced for the first time by the Chinese during the Zhou dynasty (1046-256 B.C.). Prior to that, it had not been possible to raise the temperature of the ore sufficiently to melt the iron and the only available iron was wrought iron created by heating iron ore in a furnace with carbon as the reducing agent and hammering the resulting spongy iron output. Furnaces of the day could reach temperatures of about 1300°C which was enough to melt copper whose melting point is 1083°C but not enough to melt iron whose melting point is 1528°C. By a combination of the addition of phosphorus to the ore which reduced its melting point, the use of a bellows to pump air through the ore to aid the exothermic reduction process and the use of improved high temperature refractory bricks forming the walls of the furnace to withstand the heat, the Chinese were able to melt the iron and cast it into functional shapes ranging from tools and pots and pans to heavy load bearing constructional members as well as fine ornamental pieces.

Cast iron was not produced in Europe till around 1400 A.D.. Gun-barrels and bullets were the first cast iron products to be manufactured but it was not until 1709 when Abraham Darby introduced new production methods that low cost, volume production was achieved.

See more about Chinese Inventions.

460 B.C. Another Greek philosopher Democritus of Abdera developed the idea that matter could be broken down into very small indivisible particles which he called atoms. Subsequently Aristotle dismissed Democritus' atomic theory as worthless and Aristotle's views tended to prevail. It was not until 1803 that Democritus' theory was resurrected by John Dalton.

380 B.C. Greek philosopher Plato (Circa 428-347) composed the Allegory of the Cave as part of his major work, the Republic.

He believed that there were patterns or mathematical relationships, we now would call "science", behind natural phenomena which were often hidden from the observer and difficult to observe directly.

In his allegory he described a community of prisoners permanently chained from birth to the floor of a cave facing a blank wall with no possibility to look elsewhere. See diagram of Plato's Cave. Behind the prisoners was a low wall concealing from them an elevated walkway or stage. People could walk around this stage, out of sight of the prisoners, carrying 3D objects or puppets above their heads. A fire behind the stage next to the back wall of the cave illuminated these moving objects which cast shadows on the blank wall in front of the prisoners. Any sounds of the people talking, or other movements, echoed off the walls so that the prisoners believed these sounds came from the shadows.

For the prisoners, these shadows were the reality. This was their World. They had no way of knowing that a different true reality existed. If the reality were explained to them they would probably not believe it.

The cave allegory illustrated fundamental issues in science such as:

The observer's perception of reality suffers from incomplete information and the difficulty of interpreting the information which is avavailable.

It is dangerous to infer anything about reality based on our experiences.

Plato's observations still hold good today, 2400 years later, particularly with particle physics where all is not what it seems.

350 B.C. The Greek philosopher and scientist Aristotle (384-322 B.C.), student of Plato, provided "scientific" theories based on pure "reason" for everything from the geocentric structure of the cosmos down to the four fundamental elements earth, fire, air and water.

Aristotle believed that knowledge should be gained by pure rational thought and had no time for mathematics which he regarded only as a calculating device. Neither did he support the experimental method of scientific discovery, espoused by Thales, which he considered inferior. In his support it should be mentioned that the range of experiments he could possibly undertake was limited by the lack of suitable accurate measuring instruments in his time and it was only in the seventeenth century during the Scientific Revolution that such instruments started to become available.

Unfortunately Aristotle's "rational" explanations were subsequently taken up by St Thomas Aquinas (1225-1274) and espoused by the church which for many years made it difficult, if not dangerous, to propose alternative theories. Aristotle's theories of the cosmos and chemistry thus held sway for 2000 years hampering scientific progress until they were finally debunked by Galileo, Newton and Lavoisier who showed that natural phenomena could be described by mathematical laws.

See also Gilbert (1600), Mersenne (1636), Descartes (1644) and Von Guericke (1663) and the Scientific Revolution.

Aristotle was also a tutor to the young Alexander the Great.

Like many sources from antiquity, Aristotle's original manuscripts have been destroyed or lost and we only know of Aristotle's works via series of copies and translations from the Greek into Arabic, then from Arabic into Latin and finally from Latin into English and other modern languages. There's much that could have been lost, changed or even added in the translations.

332 B.C. Alexander the Great conquered Egypt and ordered the building of a new city on the Egyptian, Nile delta named after himself - Alexandria. When he died in 323 BC his kingdom was divided between three of his generals, with Egypt going to Ptolemy (367–283 B.C.) who later declared himself King Ptolemy I Soter (not to be confused with Claudius Ptolemy (90-168 A.D.)) and founded a new dynasty, replacing the Pharaohs, which lasted until the Roman conquest of 30 B.C.

Ptolemy Soter's grandest building project in the new capital was the Musaeum or "Temple of the Muses" (from which we get the modern word "museum") which he founded around 306 B.C. A most important part of the Musaeum was the famous Library of Alexandria, which he conceived, and which was carried through by his son Ptolemy II Philadelphus, with the object of collecting all the world's knowledge. Most of the staff were occupied with the task of translating works onto papyrus and it is estimated (probably over-estimated) that as many as 700,000 scrolls, the equivalent of more than 100,000 modern printed books, filled the library shelves.

Great thinkers were invited to Alexandria to establish an academy at the library turning it into a major centre of scholarship and research. Euclid was one of the first to teach there. Ultimately the library overshadowed the Musaeum in importance and interest becoming perhaps the oldest university in the world.

It was at the library that:

Euclid developed the rules of geometry based on rigorous proofs. His mathematical text was still in use after 2000 years.

developed the rules of geometry based on rigorous proofs. His mathematical text was still in use after 2000 years. Archimedes invented the a water pump based on a helical screw, versions of which are still in use today. (The actual date of this invention is however disputed).

Eratosthenes measured the diameter of the Earth.

Hero invented the aeolipile, the first reaction turbine.

Claudius Ptolemy wrote the Almagest, the most influential scientific book about the nature of the Universe for 1,400 years.

Hypatia, the first woman scientist and mathematician invented the hydrometer, before she met her untimely end during Christian riots.

Alas the ancient library is no more. Four times it was devastated by fire, accidental or deliberate, during wars and riots and historians disagree about who were the major culprits, their motives and the extent of the damage in each case.

48 B.C. Damage caused during the Roman conquest of Egypt by Julius Caesar

272 A.D. An attack on Queen Zenobia of Palmyra by Roman Emperor Aurelian

of Palmyra by Roman 391 A.D. An edict of the Emperor Theodosius I made paganism illegal and Patriarch Theophilus of Alexandria ordered demolition of heathen temples. This was followed by Christian riots the same year and 415 A.D..

made paganism illegal and Patriarch ordered demolition of heathen temples. This was followed by Christian riots the same year and 415 A.D.. 639 A.D. The Muslim conquest of Alexandria by General Amr ibn al 'Aas leading the army of Caliph Omar of Baghdad.

But even without the wars, the delicate papyrus scrolls were apt to disintegrate with age and what was left of the library eventually succumbed to the ravages of major earthquakes in Crete in A.D. 365 and 1303 A.D. which caused tsunamis which in turn devastated Alexandria.

300 B.C. Fl Greek mathematician Euclid of Alexandria (Circa 325-265 B.C.) a great organiser and logician, taught at the great Library of Alexandria and took the current mathematical knowledge of his day and organised it into a manuscript consisting of thirteen books now known as Euclid's Elements. Considered by many to be the greatest mathematics text book ever written it has been used for over 2000 years. Nine of these books deal with plane and solid geometry, three cover number theory, one (book 10) concerns incommeasurable lengths which we would now call irrational numbers.

Proof, Logic and Deductive Reasoning

The "Elements" were not just about geometry, Euclid's theorems and conclusions were backed up by rigorous proofs based on logic and deductive reasoning and he was one of the first to require that mathematical theories should be justified by such proofs.

An example of the type of deductive reasoning applied by Euclid is the logical step based on the logical principle that if premise A implies B, and A is true, then B is also true, a principle that mediaeval logicians called modus ponens (the way that affirms by affirming). A classical example of this is the conclusion drawn from the following two premises: A: "All men are mortal" and B: "Socrates is a man" then the conclusion C: "Socrates is mortal" is also true.

In this manner Euclid started with a small set of self evident axioms and postulates and used them to produce deductive proofs of many other new propositions and geometric theorems. He wrote about plane, solid and spherical geometry, perspective, conic sections, and number theory applying rigorous formal proofs and showed how these propositions fitted into a logical system. His axioms and proofs have been a useful set of tools for many subsequent generations of mathematicians, demonstrating how powerful and beneficial deductive reasoning can be.

An example of Euclid's logical deduction is the method of exhaustion which was used as a method of finding the area of an irregular shape by inscribing inside it a sequence of n regular polygons of known area whose total area converges to the area of the given containing shape. As n becomes very large, the difference in area between the given shape and the n polygons it contains will become very small. As this difference becomes ever smaller, the possible values for the area of the shape are systematically "exhausted" as the shape and the corresponding area of the series of polygons approaches the given shape. This sets a lower limit to the possible area of the shape.

The method of exhaustion used to find the area of the shape above is a special case of of proof by contradiction, known as reductio ad absurdum which seeks to demonstrate that a statement is true by showing that a false, untenable, or absurd result follows from its denial, or in turn to demonstrate that a statement is false by showing that a false, untenable, or absurd result follows from its acceptance.

In the case above this means finding the area of the shape by first comparing it to the area of a second region inside the shape (which can be "exhausted" so that its area becomes arbitrarily close to the true area). The proof involves assuming that the true area is less than the second area, and then proving that assertion false. This gives a lower limit for the area of the shape under consideration.

Then comparing the shape to the area of a third region outside of the shape and assuming that the true area is more than the third area, and proving that assertion is also false. This gives an upper limit for the area of the shape.

No original records of Euclid's work survive and the oldest surviving version of "The Elements" is a Byzantine manuscript written in A.D. 888. Little is known of his life and the few historical references to Euclid which exist were written centuries after his death, by Greek mathematician Pappus of Alexandria around 320 A.D. and philosopher and historian Proclus around 450 A.D.

According to Proclus, when the ruler Ptolemy I Soter asked Euclid if there was a shorter road to learning geometry than through the Elements, Euclid responded "There is no royal road to geometry".

269 B.C. The greatest mathematician and engineer in antiquity, the Greek Archimedes of Syracuse (287-212 B.C.) began his formal studies at the age of eighteen when he was sent by his father, Phidias, a wealthy astronomer and kinsman of King Hieron II of Syracuse, to Egypt to study at the school founded by Euclid in the great Library of Alexandria. It kept him out of harm's way in the period leading up to the first Punic war (264-241 B.C.) between Carthage and Rome when Sicily was still a colony of Magna Graecia, vulnerably situated in strategic territory between the two adversaries. Syracuse initially supported Carthage, but early in the war Rome forced a treaty of alliance from king Hieron that called for Syracuse to pay tribute to the Romans. Returning to Syracuse in 263 B.C. Archimedes became a tutor to Gelon, the son of King Hieron.

Archimedes' Inventions

Archimedes was known as an inventor, but unlike the empirical designs of his predecessors, his inventions were the first to be based on sound engineering principles.

He was the world's first engineer, the first to be able to design levers, pulleys and gears with a given mechanical advantage thus founding the study of mechanics and the theory of machines.

Archimedes also founded the studies of statics and hydrostatics and was the first to elucidate the principle of buoyancy and to use it in practical applications.

Though he did not invent the lever , he explained its mechanical advantage , or leverage, in his work "On the Equilibrium of Planes" and is noted for his claim "Give me a place to stand and a long enough lever and I can move the Earth".

, he explained its , or leverage, in his work "On the Equilibrium of Planes" and is noted for his claim "Give me a place to stand and a long enough lever and I can move the Earth". Archimedes' explanation of the theory of the lever is based on the principle of balancing the input and output torques about the fulcrum of the device so that, the input force multiplied by its distance from the fulcrum, is equal to the weight (or downward force) of the load multiplied by its distance from the fulcrum. In this arrangement, the distance moved by each force is proportional to its distance from the fulcrum. Thus a small force moving a long distance can lift a heavy load over a small distance and the mechanical advantage is equal to the ratio of the distances from the fulcrum of the points of application the input force and the output force. He applied similar reasoning to explain the operation of compound pulleys and gear trains, in the latter case using angular displacement in place of linear displacement. We would now relate this theory to the concepts of work done, potential energy and the conservation of energy. See also hydraulic, mechanical advantage described by Pascal. He is credited by the Greek historian Plutarch (46-120 A.D.), with inventing the block and tackle / compound pulley to move ships and other heavy loads. The use of a simple, single-sheaved pulley to change the direction of the pull, for drawing water and lifting loads had been known for many years. This device did not provide any mechanical advantage, but Archimedes showed that a multi-sheaved, compound pulley could provide a mechanical advantage of n where n is the number of parts of the rope in the pulley mechanism which support the moving block. For example, a block and tackle system with three sheaves or pulley wheels in the upper block and two sheaves in the lower (suspended) block will have five sections of the rope supporting the load giving a mechanical advantage of five. Pulling the rope by five feet with a force of one pound will draw the pulley blocks one foot closer together, raising the load by one foot. The tension on the rope will be the same throughout its length, so that the five sections of the rope between the pulleys, together provide a combined lifting force of five pounds on the lower block. Thus the affect on the load is that the mechanism multiplies the force applied by five but divides the distance moved by five.

(46-120 A.D.), with inventing the to move ships and other heavy loads. The use of a simple, single-sheaved pulley to change the direction of the pull, for drawing water and lifting loads had been known for many years. This device did not provide any mechanical advantage, but Archimedes showed that a multi-sheaved, compound pulley could provide a mechanical advantage of where is the number of parts of the rope in the pulley mechanism which support the moving block. For example, a block and tackle system with three sheaves or pulley wheels in the upper block and two sheaves in the lower (suspended) block will have five sections of the rope supporting the load giving a mechanical advantage of five. Pulling the rope by five feet with a force of one pound will draw the pulley blocks one foot closer together, raising the load by one foot. The tension on the rope will be the same throughout its length, so that the five sections of the rope between the pulleys, together provide a combined lifting force of five pounds on the lower block. Thus the affect on the load is that the mechanism multiplies the force applied by five but divides the distance moved by five. Similarly, Archimedes was familiar with gearing , which had been mentioned in the writings of Aristotle about wheel drives and windlasses around 330 B.C., and was able to calculate the mechanical advantage provided by the geared mechanisms of simple spur gears. Archimedes is however credited with the invention of the worm gear which not only provided much higher mechanical advantage, it also had the added advantage that the "worm", actually a helical screw, could easily rotate the gear wheel but the gear wheel could not easily, if at all, rotate the worm. This gave the mechanism a ratchet like, or braking, property such that heavy loads would not slip back if the input force was relaxed.

, which had been mentioned in the writings of Aristotle about and around 330 B.C., and was able to calculate the mechanical advantage provided by the geared mechanisms of simple spur gears. Archimedes is however credited with the invention of the which not only provided much higher mechanical advantage, it also had the added advantage that the "worm", actually a helical screw, could easily rotate the gear wheel but the gear wheel could not easily, if at all, rotate the worm. This gave the mechanism a ratchet like, or braking, property such that heavy loads would not slip back if the input force was relaxed. It is said that he invented a screw pump, known after him as the Archimedes' Screw , for raising water by means of a hollow wooden pipe containing a close fitting wooden, helical screw on a long shaft turned by a handle at one end. When the other end was placed in the water to be raised and the handle turned, water was carried up the tube by the screw and out at the top. However such devices probably predated Archimedes and were possibly used in the Hanging Gardens of Babylon. The Archimedes' Screw is still used today as a method of irrigation in some developing countries.

, for raising water by means of a hollow wooden pipe containing a close fitting wooden, helical screw on a long shaft turned by a handle at one end. When the other end was placed in the water to be raised and the handle turned, water was carried up the tube by the screw and out at the top. However such devices probably predated Archimedes and were possibly used in the Hanging Gardens of Babylon. The Archimedes' Screw is still used today as a method of irrigation in some developing countries. He also designed winches, windlasses and military machines including catapults, trebuchets and siege engines.

It is claimed by some that Archimedes invented the odometer but this is more likely to be the work of Vitruvius who described its working details.

who described its working details. Fanciful claims have also been made that he designed gear mechanisms for moving extremely heavy loads, an Iron Claw to lift ships out of the water causing them to break up and a Death Ray to set approaching ships on fire. See more about these claims below.



Archimedes' Mathematics

While Archimedes was famous for his inventions, his mathematical writings were equally important but less well known in antiquity. Mathematicians from Alexandria read and quoted him, but the first comprehensive compilation of his work was not made until Circa. 530 A.D. by Isidore of Miletus.

Archimedes was able to use infinitesimals in a way that is similar to modern integral calculus . Through proof by contradiction (reductio ad absurdum), he could give answers to problems to an arbitrary degree of accuracy, while specifying the limits within which the answer lay.

in a way that is similar to modern . Through proof by contradiction (reductio ad absurdum), he could give answers to problems to an arbitrary degree of accuracy, while specifying the limits within which the answer lay. Though mathematicians had been aware for many years that the ratio π between the circumference and the diameter of a circle was a constant, there were wide variations in the estimations of its magnitude. Archimedes calculated its value to be 3.1418, the first reasonably accurate value of this constant.

between the circumference and the diameter of a circle was a constant, there were wide variations in the estimations of its magnitude. Archimedes calculated its value to be 3.1418, the first reasonably accurate value of this constant. He did it by using the method of exhaustion to calculate the circumference of a circle rather than the area and by dividing the circumference by the diameter he obtained the value of π. First he drew a regular hexagon inside a circle and computed the length of its perimeter. Then he improved the accuracy by progressively increasing the number of sides of the polygon and calculating the perimeter of the new polygon with each step. As the number of sides increases, it becomes a more accurate approximation of a circle. At the same time, by circumscribing the circle with a series of polygons outside of the circle, he was able to determine an upper limit for the perimeter of the circle. He found that with a 96 sided polygon the lower and upper limits of π calculated by his method were given by: 223/ 71 < π < 22/ 7 In modern decimal notation this converts to: 3.1408 < π < 3.1428 The value of π calculated by Archimedes is given by the average between the two limits and this is 3.1418 which is within 0.0002 of its true value of 3.1416. More generally, Archimedes calculated the area under a curve by imagining it as a series of very thin rectangles and proving that the sum of the areas of all the rectangles gave a very close approximation to the area under the curve. Using the method of exhaustion he showed that the approximation was neither greater nor smaller than the area of the figure under consideration and therefore it must be equal to the true area. He was thus able to calculate the areas and volumes of different shapes and solids with curved sides. This method anticipated the methods of integral calculus introduced nearly 2000 years later by Gregory, Newton and Leibniz.

introduced nearly 2000 years later by Gregory, Newton and Leibniz. He was also able to calculate the sum of a geometric progression.

He proved that the area of a circle was equal to π multiplied by the square of the radius of the circle (πr 2 ) and that the volume and surface area of sphere are 2/3 of a cylinder with the same height and diameter.

multiplied by the square of the radius of the circle and that the volume and surface area of sphere are 2/3 of a cylinder with the same height and diameter. Thus he showed that the surface area A of a sphere with radius r is given by: A = 4 π r2 and the volume V of a sphere with radius r is given by: V = 4/3π r3 which he regarded as one of his proudest achievements. He also developed fundamental theorems concerning the determination of the centre of gravity of plane figures.

In an attempt to calculate how many grains of sand it would take to fill the Universe, Archimedes devised a number system which he called the Sand Reckoner to represent the very large numbers involved. Based on the largest number then in use called the myriad equal to 10,000 he used the concept of a myriad-myriads equal to 108. He called the numbers up to 108 "first numbers" and called 108 itself the "unit of the second numbers". Multiples of this unit then became the second numbers, up to this unit taken a myriad-myriad times, 108·108=1016. This became the "unit of the third numbers", whose multiples were the third numbers, and so on so that the largest number became (108) raised to the power (108) which in turn is raised to the power (108).

Myths and Reality

As with many great men of antiquity, few if any, contemporary records of Archimedes works remain and his reputation has been embellished by historians writing about him many years after his death, or trashed by artists, ignorant of the scientific principles involved, attempting to illustrate his ideas. This is probably the case with four of the oft quoted anecdotes about his work.

It is claimed that Archimedes used a mirror or mirrors on the shore to focus the Sun's rays, the so called Death Rays onto attacking ships to destroy them by setting them on fire. (The Greeks had much more practical incendiary missiles available to them at the time and catapults to throw them long distances)

onto attacking ships to destroy them by setting them on fire. (The Greeks had much more practical incendiary missiles available to them at the time and catapults to throw them long distances)

Similarly it is reported that Archimedes used his compound pulley system connected to an Iron Claw suspended from a beam to lift the prows of attacking ships out of the water causing them to break up or capsize and sink. (The ships would have to be almost on the beach, directly in front of the defensive claw, to be in range of these machines.)

suspended from a beam to lift the prows of attacking ships out of the water causing them to break up or capsize and sink. (The ships would have to be almost on the beach, directly in front of the defensive claw, to be in range of these machines.)

He was also familiar with geared mechanisms and it was claimed by third century historian, Athenaeus , that Archimedes' systems of winches and pulleys would enable a few men to launch a huge boat into the sea or to carry it on land. These mechanisms were illustrated by Gian Maria Mazzucchelli in his 1737 biography of Archimedes. It is quite clear from the drawings that the wooden gear wheels would have been unable to transmit the power required and the tensile strength of the ropes employed is also questionable.

and it was claimed by third century historian, , that Archimedes' systems of winches and pulleys would enable a few men to launch a huge boat into the sea or to carry it on land. These mechanisms were illustrated by Gian Maria in his 1737 biography of Archimedes. It is quite clear from the drawings that the wooden gear wheels would have been unable to transmit the power required and the tensile strength of the ropes employed is also questionable.

Over the years, in the absence of written records, other artists and illustrators have tried to depict Archimedes devices and mechanisms. Examples of how the artists have imagined these devices are shown in the page about Archimedes' Machines

The most widely known anecdote about Archimedes is the Eureka story told two centuries later by the Roman architect and engineer Vitruvius. According to Vitruvius, King Hieron II had supplied a pure gold ingot to a goldsmith charged with making a new crown. The new crown when delivered weighed the same as the ingot supplied but the King wanted Archimedes to determine whether the goldsmith had adulterated the gold by substituting a portion of silver. Archimedes was aware that silver is less dense than gold so he would be able to to determine whether some of the gold had been replaced by silver by checking the density. He had a balance to check the weight, but how could he determine the volume of an intricately designed crown without melting it down or otherwise damaging it? While taking a bath, he noticed that the level of the water in the tub rose as he got in, and realised that this effect could be used to determine the volume of the crown. By immersing the crown in water, the volume of water displaced would equal the volume of the crown. If any of the gold had been replaced by silver or any other less dense metal, then the crown would displace more water than a similar weight of pure gold. EUREKA!!!. It was reported that Archimedes then took to the streets naked, so excited by his discovery that he had forgotten to dress, crying "Eureka!" (Greek: meaning "I have found it!"). The test was conducted successfully, proving that silver had indeed been mixed in. There is no record of what happened to the goldsmith. It is claimed today that the change in volume would probably have been so small as to be undetectable by the apparatus available to Archimedes at the time. There is no question however that he devised a method of measuring the volume of irregularly shaped objects and also understood the principle of buoyancy and its use for comparing the density of the materials used in different objects, but the story of him running naked through the streets is probably apocryphal.

All of these stories probably contain a major element of truth and it would not be surprising that Archimedes was well aware of, and had publicised, the theoretical possibilities involved in these schemes, but whether they could have actually been successfully implemented with the available technology and materials of the day is open to question. The principles were correct but the scale and effectiveness of the devices described in biographies written hundreds of years later was doubtful. There is unfortunately no corroborating evidence to back up these later descriptions of the military exploits. If the naval siege defences had been so successful, why would they not have been subsequently adopted as standard practice and why did they not appear in historical accounts of the battles?

Death of Archimedes

By 215 B.C. Hostilities between Carthage and Rome flared up once more in the second Punic War and in 214 B.C. and Syracuse sided once more with the Carthaginians and so came under siege by the Romans under General Marcus Claudius Marcellus. Archimedes skills in designing military machines and mechanical devices were well known, even to the Romans, and were called upon in the defence of Syracuse during these hostilities.

Greek historian Plutarch (C. 46 – 120 A.D.) gave two accounts of Archimedes' death in 212 B.C. when Roman forces eventually captured the city after a two year siege. The first describes how Archimedes was contemplating a mathematical problem on a diagram he had drawn in the dust on the ground when he was approached by a Roman soldier who commanded him to come and meet General Marcellus who considered the great inventor to be a valuable scientific asset who should not be harmed. But Archimedes declined, saying that he had to finish working on the problem. The soldier was enraged by this, and ran him through with his sword, much to the annoyance of Marcellus.

The second account explains that Archimedes was killed by a soldier while attempting to rob him of his valuable mathematical instruments.

Recent examination of all the accounts by both Carthaginian and Roman historians of the details of Archimedes' death have however reached a different conclusion. As we know, history is often written by the winners. The counter view is that Archimedes' death was the state-sponsored assassination of an enemy of Rome, a key player, whose inventions were vital to the defence of Syracuse. The nations were at war. Why would Archimedes be so oblivious to the danger he was in? Marcellus' feigned sorrow and anger after the event were a cover for his guilt at ordering the death of the World's greatest scientist at the time.

250 B.C. The Baghdad Battery - In 1936 several unusual earthenware jars, dating from about 250 B.C., were unearthed during archeological excavations at Khujut Rabu near Baghdad. A typical jar was 130 mm (5-1/2 inches) high and contained a copper cylinder, the bottom of which was capped by a copper disk and sealed with bitumen or asphalt. An iron rod was suspended from an asphalt stopper at the top of the copper cylinder into the centre of the cylinder. The rod showed evidence of having been corroded with an acidic agent such as wine or vinegar. 250 BC corresponds to the Parthian occupation of Mesopotamia (modern day Iraq) and t jars were held in Iraq's State Museum in Baghdad. (Baghdad was not founded until 762 A.D.) 1938 they were examined by German archeologist Wilhelm König who concluded that they were Galvanic cells or batteries supposedly used for gilding silver by electroplating. A mysterious anachronism. Backing up his claim, König also found copper vases plated with silver dating from earlier periods in the Baghdad Museum and other evidence of (electro?)plated articles from Egypt. Since then, several replica batteries have been made using various electrolytes including copper sulphate and grape juice generating voltages from half a Volt to over one Volt and they have successfully been used to demonstrate the electroplating of silver with gold. One further, more recent, suggestion by Paul T. Keyser a specialist in Neat Eastern Studies from the University of Alberta is that the galvanic cells were used for analgesia. There is evidence that electric eels had been used to numb an area of pain, but quite how that worked with such a low voltage battery is not explained. Apart from that, no other compelling explanation of the purpose of these artifacts has been proposed and the enigma still remains.

Despite warnings about the safety of these priceless articles before the 2003 invasion of Iraq, they were plundered from the museum during the war and their whereabouts is now unknown.

A nice and oft repeated story but there is a counter view about their purpose.

The Parthians were nomadic a nomadic tribe of skilled warriors and not noted for their scientific achievements. The importance of such an unusual electrical phenomenon seems to have gone completely unrecorded within the Parthian and contemporary cultures and then to have been completely forgotten despite extensive historical records from the period.

There are also some features about the artifacts themselves which do not support the battery theory. The asphalt completely covers the copper cylinder, electrically insulating it so that no current could be drawn without modifying the design and no wires, conductors, or any other sort of electrical equipment associated with the artifacts have been found. Furthermore the asphalt seal forms a perfect seal for preventing leakage of the electrolyte but it would be extremely inconvenient for a primary galvanic cell which would require frequent replacement of the electrolyte. As an alternative explanation for these objects, it has been noted that they resemble storage vessels for sacred scrolls. It would not be at all surprising if any papyrus or parchment inside had completely rotted away, perhaps leaving a trace of slightly acidic organic residue.

240 B.C. Greek mathematician Eratosthenes(276-194 B.C.) of Cyrene (now called Shahhat, Libya), the third chief librarian at the Library of Alexandria and contemporary of Archimedes calculated the Circumference of the Earth. Considering the tools and knowledge available at the time, Eratosthenes results are truly brilliant. Equipped with only a stick, he did not even need to leave Alexandria to make this remarkable breakthrough. Not only did he know that the Earth was spherical, 1700 years before Columbus was born, he also knew how big it was to an accuracy within 1.5%. See Eratosthenes Method and Calculation.

He invented the discipline of geography including the terminology still used today and created the first map of the world incorporating parallels and meridians, (latitudes and longitudes) based on the available geographical knowledge of the era. He was also the first to calculate the tilt of the Earth's axis (again with remarkable accuracy) and he deduced that the calendar year was 365 1/4 days long and was first to suggest that every four years there should be a leap year of 366 days.

Eratosthenes also devised a way of finding prime numbers known as the sieve. Instead of using trial division to sequentially test each candidate number for divisibility by each prime which is a very slow process, his system marks as composite (i.e. not prime) the multiples of each prime, starting with the multiples of 2, then 3 and continues this iteratively so that they can be separated out. The multiples of a given prime are generated as a sequence of numbers starting from that prime, with constant difference between them which is equal to that prime.

220-206 B.C. The magnetic compass was invented by the Chinese during the Qin (Chin) Dynasty, named after China's first emperor Qin Shi Huang di, the man who built the wall. It was used by imperial magicians mostly for geomancy (Feng Shui and fortune telling) but the "Mighty Qin's" military commanders were supposed to be the first to use a lodestone as a compass for navigation. Chinese compasses point south.

See more about Chinese Inventions.

206 B.C. - 220 A.D. During the Han Dynasty, Chinese historian Ban Gu recorded in his Book of Han the existence of pools of "combustible water", most likely petroleum, in what is now China's Shaanxi province. During the same period, in Szechuan province, natural gas was also recovered from what they called "fire wells" by deep drilling up to several hundred feet using percussion drills with cast iron bits. These fuels were used for domestic heating and for extracting metals from their ores (pyrometallurgy), for breaking up rocks as well as for military incendiary weapons. The heavy oil was also distilled to produce paraffin (kerosene) for use in decorative oil lamps from the period which have been discovered.

Percussion drilling involves punching a hole into the ground by repeatedly raising and dropping a heavy chisel shaped tool bit into the bore hole to shatter the rock into small pieces which can be removed. The drill bit is raised by a cable and pulley system suspended from the top of a wooden tower called a derrick.

The fuels were later named in Chinese as shíyóu rock oil by Shen Kuo just as the word petroleum is derived from the latin petra rock and oleum oil.

It was over 2000 years before the first oil well was drilled by Edwin Drake in the USA and he used the same percussion drilling method as the Chinese.

See more about Chinese Inventions.

140 - 87 B.C. Paper was first produced in China in the second century B.C.. Made by pounding and disintegrated hemp fibres, rags and other plant fibres in water followed by drying on a flat mould, the paper was thick and coarse and surprisingly it was not used for writing but for clothing, wrapping, padding and personal hygiene. The oldest surviving piece of paper was found in a tomb near Xian and dates from between 140 B.C. to 87 B.C. and is inscribed with a map.

The first paper found with writing on it was discovered in the ruins of an ancient watch tower and dates from 105 A.D. The development of this finer paper suitable for writing is attributed to Cai Lun, a eunuch in the Imperial court during the Han dynasty (202 B.C. - A.D. 220).

Paper was an inexpensive new medium which provided a simple means of communicating accurately with others who were not present without the danger of "Chinese whispers" corrupting the message, but more importantly, it enabled knowledge to be spread to a wider population or recorded for use by future generations. A simple invention which, like the printing press, brought enormous benefits to society.





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27 B.C. - 5th Century A.D. The Roman Empire. The Romans were great plumbers but poor electricians.

The Romans were deservedly renowned for their civil engineering - buildings, roads, bridges, aqueducts, central heating and baths. Surprisingly however, in 500 years, they didn't advance significantly on the legacies of mathematics and scientific theories left to them by the Greeks. Fortunately, the works of the Greek philosophers and mathematicians were preserved by Arab scholars who translated them into Arabic.

Circa 15 B.C. Some time between 27 B.C and 15 B.C. Roman architect and military engineer, Marcus Vitruvius Pollio, completed "De Architectura" or "On Architecture: The Ten Books on Architecture". It is a comprehensive manual for architects covering the principles of architecture, education and training, town planning, environment, structures, building materials and construction methods, design requirements for buildings intended for different purposes, proportions, decorative styles, plans for houses, heating, acoustics, pigments, hydraulics, astronomy and a ranges of machinery and instruments.

His philosophies about architecture are summed up in the Vitruvian Virtues that a structure must exhibit the three qualities of firmitas, utilitas, venustas - meaning that it must be solid, useful and beautiful.

Included in Book 10 of the study are designs for military and hydraulic machines, including pulleys and hoists and designs for trebuchets, water wheels and armoured vehicles which have had an undeniable influence on the inventions of Leonardo da Vinci. See more about Vitruvius water wheels.

Amongst Vitruvius' designs are instructions for the design of an odometer which he called a "hodometer". It consisted of a cart with a separate, large wheel of known circumference mounted in a frame. The large wheel was connected through the intermediate gear wheel of a reduction gear mechanism to a horizontal disk with a series of holes around its rim each containing a small pebble. A single hole in the housing of the horizontal disk allowed a pebble to fall through into a container below when it arrived above the hole. As the cart was pushed along the ground, one pebble would fall into the container for each revolution of the intermediate gear wheel. The distance traveled could be calculated by counting the number of pebbles in the container and multiplying by the circumference of the large wheel and the gear ratio. Vitruvius also proposed a marine version of his device in which the distance was calculated from the rotation of paddles.

There are some who attribute the design of the odometer to Archimedes, but there is no strong evidence to support this.

Unfortunately none of the original illustrations from "De Architectura" have survived. Nevertheless the books have deeply influenced classical architects from the Renaissance through to the twentieth century. He was perhaps a little too influential though, through no fault of his own, since his style was so sublime that it captured public taste, stifling further innovation and generations of architects merely copied his ideas rather than developing alternative styles of their own.

Vitruvius has been called the world's first engineer to be known by name.

1 B.C.

1 A.D.

Circa 50 A.D. In the first century A.D. several spectacular aqueducts were built by Roman Engineers and though many of them are still standing and in some cases still in use, there are unfortunately no records of who actually designed and built them. Two which stand out are the Pont du Gard near Nimes in France, the other at Segovia in Spain.

(See pictures of these two Roman Aqueducts)

In the absence of records the design and construction of the Pont du Gard has been attributed to Marcus Agrippa, the adopted son-in-law of Emperor Augustus at around the year 19 B.C. However recent excavations and coins depicting the Emperor Claudius (41-54 A.D.) found at the site suggest that the construction may have taken place between 40 and 60 A.D. The aqueduct supplied Nimes with water and is nearly 30 miles (50 kilometres) long. The section over the river Gard has arches at three levels and is 900 feet (275 metres) long and 160 feet (49 metres) high. The top level contains a channel 6 feet (1.8 metres) high and 4 feet (1.2 metres) wide with a gradient of 0.4 per cent to carry the water. The bottom level carries a roadway. The three levels were built in dressed stone without mortar.

Some researchers have estimated that the Segovia aqueduct was started in the second half of the 1st Century A.D. and completed in the early years of the 2nd Century, during the reign of either Emperor Vespasian (69-79 A.D.) or Nerva (96-98 A.D.). Others have suggested it was started under Emperor Domitian (81-96 A.D.) and probably completed under Trajan (98-117 A.D.). The aqueduct brought water to Segovia from the Frio River 10 miles (16 km) away. Its maximum height is 93 ft 6 in (28.5 metres), including nearly 19 ft 8 in (6 metres) of foundations and it is constructed from 44 double arches, 75 single arches and another four single arches giving a total of 167 arches. The bridge section of the aqueduct is 2240 feet (683 meters) long and changes direction several times. Like the Pont du Gard, it was built from dressed stone without mortar.

Circa 60 A.D. Greek mathematician Hero of Alexandria conceived the idea of a reaction turbine though he didn't call it that. He called it an Aeolipile (Aeolus - Greek God of the Wind) (Pila Latin - Ball) or the Sphere of Aeolus. It was a hollow sphere containing a small amount of water, free to rotate between two pivot points. When heated over a flame the steam from the boiling water escaped through two tangential nozzles in jets which caused the sphere to rotate at high speed. See diagram of Hero's Aeolipile.

Alternative designs show the water boiled in a separate chamber being fed through a hollow pipe into the sphere through one of the pivots.

It has been suggested that this device was used by priests to perform useful work such as opening temple doors and moving statues to impress gullible worshippers but no physical evidence remains and these ideas were never developed and the aeolipile remained as a toy.

Hero is also credited as being the first to propose a formal way of calculating square roots.

See more about Reaction Turbines.

See more about Steam Engines

150 A.D. Some time between 150 A.D. and 160 A.D. Greek astronomer and mathematician Claudius Ptolemaeus, Ptolemy a Roman citizen of Alexandria, (not one of the Ptolomaic Kings) published the Almagest "The Great Book". In it he summarised the all known information about astronomy and the mathematics which supported the theories. For over a thousand years it was the accepted explanation of the workings of the Universe. Unfortunately it was based on a geocentric model with uniform circular motions of the Sun and planets around the Earth. Where this ideal motion did not fit the observed movements, the anomalies were explained by the concept of equants with the planets moving in smaller epicyclic orbits superimposed on the major orbit. It was not until Copernicus came along 1400 years later that Ptolemy's theory was seriously challenged. The Almagest was however a major source of information about Greek trigonometry.

In a similar vein to the Almagest, Ptolemy also published Geographia which summarised all that was known at the time about the World's geography as well as the projections used to create more accurate maps.

200 Greek philosopher Claudius Galen from Pergamum, Asia Minor, physician to five Roman emperors and surgeon to the Roman gladiators, was the first of many to claim therapeutic powers of magnets and to use them in his treatments. Galen carried out controlled experiments to support his theories and was the first to conclude that mental actively occurred in the brain rather than the heart, as Aristotle had suggested. Like many ancient philosophers his authority was virtually undisputed for many years after his death, thus discouraging original investigation and hampering medical progress until the 16th century.

But see Vesalius.

400 Greek scholar Hypatia of Alexandria took up her position as head of the Platonist school at the great Library of Alexandria, (in the period between its third and its fourth and final sacking), where she taught mathematics, astronomy and philosophy. The first recorded woman in science, she is considered to be the inventor of the hydrometer, called the aerometer by the Greeks. Claims that she also invented the planar astrolabe are probably not true since there is evidence that the astrolabe dates from 200 years earlier, but her mathematician father Theon of Alexandria had written a treatise on the device and she no doubt lectured about its use for calculating the positions of the Sun, Moon and stars.

Hypatia still held pagan beliefs at a time when the influence of Christianity was beginning to grow and unfortunately her science teachings were equated with the promotion of paganism. In 415 she was attacked by a Christian mob who stripped her, dragged her through the streets, killed her and cut her to pieces using oyster shells. Judging from her appearance as depicted by Victorian artists, it's no surprise that the local monks were outraged. See Hypatia 1885 by Charles William Mitchell.

426 Electric and magnetic phenomena were investigated by St Augustine who is said to have been "thunderstruck" on witnessing a magnet lift a chain of rings. In his book "City of God" he uses the example of magnetic phenomena to defend the idea of miracles. Magnetism could not be explained but it manifestly existed, so miracles should not be dismissed just because they could not be explained.

619 In 1999, archaeologists at Nendrum on Mahee Island in Ireland investigating what they thought to be a stone tidal pond used for catching fish uncovered two stone built tidal mills with a millstones and paddle blades dating from 619 AD and 787 AD. Several tidal mills were built during the Roman occupation of England for grinding grain and corn. They operated by storing water behind a dam during high tide, and letting it out to power the mill after the tide had receded and were the forerunners of the modern schemes for capturing tidal energy.

645 Xuan Zhuang the great apostle of Chinese Buddhism returned to China from India with Buddhist images and more than 650 Sanskrit Buddhist scriptures which were reproduced in large quantities giving impetus to the refinement of traditional methods of printing using stencils and inked squeezes first used by the Egyptians. A pattern of rows of tiny dots was made in a sheet of paper which was pressed down on top of a blank sheet and ink was forced through the holes. Later stencils developed by the Chinese and Japanese used human hair or silk thread to tie delicate isolated parts into the general pattern but there was no fabric backing to hold the whole image together. The stencil image was printed using a large soft brush, which did not damage the delicate paper pattern or the fine ties. These printing techniques of composite inked squeezes and stencils foreshadowed modern silk screen printing which was not patented until 1907.

700 - 1100 Islamic Science During Roman times, the flame of Greek science was maintained by Arab scholars who translated Greek scientific works into Arabic. From 700 A.D. however, when most of Europe was still in the Dark Ages, scientific developments were carried forward on a broad front by the Muslim world with advances in astronomy, mathematics, physics, chemistry and medicine. Chemistry (Arabic Al Khimiya "pour together", "weld") was indeed the invention of the Muslims who carried out pioneering work over three centuries putting chemistry to practical uses in the refinement of metals, dyeing, glass making and medicine. In those days the notion of alchemy also included what we would today call chemistry. Among the many notable muslim scientists from this period were Jabir Ibn Haiyan, Al-Khawarizmi and Al-Razi.

By the tenth century however, according to historian Toby Huff, the preeminence of Islamic science began to wane. It had flourished in the previous three centuries while Muslims were in the minority in the Islamic regions however, starting in the tenth century, widespread conversion to Islam took place and as the influence of Islam increased, so the tolerance of alternative educational and professional institutions and the radical ideas of freethinkers decreased. They were dealt a further blow in 1485, thirty five years after the invention of the printing press, when the Ottoman Sultan Byazid II issued an order forbidding the printing of Arabic letters by machines. Arabic texts had to be translated into Latin for publication and this no doubt hampered both the spread of Islamic science and ideas as well as the influence of the outside world on the Islamic community. This prohibition of printing was strictly enforced by subsequent Ottoman rulers until 1728 when the first printing press was established in Istanbul but due to objections on religious grounds it closed down in 1742 and the first Koran was not printed in Istanbul until 1875. Meanwhile in 1734 Deacon Abdalla Zakhir of the Greek Catholic Maronite Monastery of Saint John Sabigh in the Lebanon managed to establish the first independent Arabic printing press.

Islam was not alone in banning the dissemination of subversive or inconvenient ideas. Henry VIII in 1529, aware of the power of the press, became the first monarch to publish a list of banned books though he did not go so far as banning printing. He was later joined by others. In 1632 Galileo's book "Dialogue Concerning the Two Chief World Systems", in which he asserted that the Earth revolved around the Sun rather than the other way round, was placed by Pope Urban VIII on the index of banned books and Galileo was placed under house arrest. Despite these setbacks, European scientific institutions overcame the challenges by the church, taking over the flame carried by the Arabs and the sixteenth and seventeenth centuries became the age of Scientific Revolution in Europe.

776 Persian chemist Abu Musa Jabir Ibn Haiyan (721-815), also known as Geber, was the first to put chemistry on a scientific footing, laying great emphasis on the importance of formal experimentation. In the period around 776 A.D. he perfected the techniques of crystallisation, distillation, calcination, sublimation and evaporation and developed several instruments including the alembic (Arabic al-ambiq, "still") which simplified the process of distillation, for carrying them out. He isolated or prepared several chemical compounds for the first time, notably nitric, hydrochloric, citric and tartaric acids and published a series of books describing his work which were used as classic works on alchemy until the fourteenth century. Unfortunately the books were added to, under Geber's name, by various translators in the intervening period leading to some confusion about the extent of Geber's original work.

830 Around the year 830, Baghdad born mathematician Mohammad Bin Musa Al-Khawarizmi (770-840) published "The Compendium Book on Calculation by Completion and Balancing" in which he introduced the principles of algebra (Arabic Al-jabr "the reduction" i.e. of complicated relationships to a simpler language of symbols) which he developed for solving linear and quadratic equations. He also introduced the decimal system of Hindu-Arabic numerals to Europe as well as the concept of zero, a mathematical device at the time unknown in Europe used to Roman numerals. Al-Khawarizmi also constructed trigonometric tables for calculating the sine functions. The word algorithm (algorizm) is named after him.

850 Historian of Chinese inventions, Joseph Needham, identified 850 as the date of the first appearance of what the Chinese called the "fire chemical" or what we would now call gunpowder. Around that year, a book attributed to Chinese alchemist Cheng Yin warns of the dangerous incendiary nature of mixtures containing saltpetre (potassium nitrate), and sulphur, both essential components of gunpowder. Such chemicals mixed with various other substances including carbonaceous materials and arsenic had been used in various concentrations by alchemists since around 300 A.D. when Ko Hung proposed these mixtures in recipes for transforming lead into gold and mercury into silver while others later used them in attempts to create a potion of immortality.

After Cheng Yin's warning, similar mixtures were soon developed to produce flares and fireworks as well as military ordnance including burning bombs and fuses to ignite flame throwers burning petrol (gasoline). The first example of a primitive gun called a "fire arrow" appeared in 905, and in 994, arrows tipped with burning "fire chemicals" were used to besiege the city of Tzu-t'ung.

Most of these military applications were merely incendiary devices rather than explosives since they did not yet contain enough saltpetre (75%) to detonate. It was not until 1040 that the full power of the saltpetre rich mixture was discovered and the first true formula for gunpowder was published by Tseng Kung-Liang. After that, true explosive devices were developed including cannon and hand grenades and land mines.

Around 1150 it was realised that an arrow could be made to fly without the need for a bow by attaching to the shaft, a bamboo tube packed with a burning gunpowder mix. This led to the development of the rocket which was born when larger projectiles were constructed from the bamboo sticks alone without the arrows. A text from around that time describes how the combustion efficiency and hence the rocket thrust could be improved by creating a cavity in the propellant along the centre line of the rocket tube to maximise the burning surface - a technique still used in solid fuelled rockets today.

In 1221 Chinese chronicler Chao Yu-Jung recorded the first use of bombs which we would recognise today, with cast iron casings packed with explosives, which created deadly flying shrapnel when they exploded. They were used to great effect by a special catapult unit in Genghis Khan's Mongol army and by the Chinese Jin forces to defeat their Song enemies in the 1226 siege of Kaifeng.

See more about Nobel and Explosives.

920 Around the year 920, Persian chemist Mohammad Ibn Zakariya Al-Razi (865-925), known in the West as Rhazes, carried on Geber's work and prepared sulphuric acid, the "work horse" of modern chemistry and a vital component in the world's most common battery. He also prepared ethanol, which was used for medicinal applications, and described how to prepare alkali (Al-Qali, the salt work ashes, potash) from oak ashes. Al-Razi published his work on alchemy in his "Book of Secrets". The precise amounts of the substances he specified in his recipes demonstrates an understanding of what we would now call stoichiometry.

Several more words for chemicals are derived from their Arabic roots including alcohol (Al Kuhl" "essence", usually referring to ethanol) as well as arsenic and borax.

1000

1040 Thermoremanent magnetisation described in the Wu Ching Tsung Yao "Compendium of Military Technology" in China. Compass needles were made by heating a thin piece of iron, often in the shape of a fish, to a temperature above the Curie Point then cooling it in line with the Earth's magnetic field.

1041 Between 1041 and 1048 Chinese craftsman Pi Sheng produced the first printing press to use moveable type. Although his designs achieved widespread use in China, it was another four hundred years before the printing press was "invented" by Johann Gutenberg in Europe.

See more about Chinese Inventions.

1086 During the Song Dynasty (960-1127), Chinese astronomer, cartographer and mathematician Shen Kuo, in his Dream Pool Essays, describes the compass and its use for navigation and cartography as well as China's petroleum extraction and Pi Sheng's printing technique.

See more about Chinese Inventions.

1190 The magnetic compass "invented" in Europe 1400 years after the Chinese. Described for the first time in the west by a St Albans monk Alexander Neckam in his treatise De Naturis Rerum.

1250's Italian theologian St Thomas Aquinas stands up for the cause of "reason" reconciling the philosophy of Aristotle with Christian doctrine. Challenging Aristotle now became a challenge to the Church.

See also the Scientific Revolution

1269 Petrus Peregrinus de Marincourt, (Peter the Pilgrim) a French Crusader, used a compass to map the magnetic field of a lodestone. He discovered that a magnet had two magnetic poles, North and South and was the first to describe the phenomena of attraction and repulsion. He also speculated that these forces could be harnessed in a machine.

1285 The earliest record of a mechanical clock with an escapement or timing control mechanism is a reference to a payment to a clock keeper at (the original) St. Paul's in London. The invention of the verge and foliot escapement was an important breakthrough in measuring the passage of time allowing the development of mechanical timepieces.

The name verge comes from the Latin virga, meaning stick or rod. (See picture and explanation of the Verge Escapement)

The inventor of the verge escapement is not known but we know that it dates from 13th century Europe, where it was first used in large tower clocks which were built in town squares and cathedrals. The earliest recorded description of an escapement is in Richard of Wallingford's 1327 manuscript Tractatus Horologii Astronomici on the clock he built at the Abbey of St. Albans. It was not a verge, but a more complex variation.

For over 200 years the verge was the only escapement used in mechanical clocks until alternative escapements started to appear in the 16th century and it was 350 years before the more accurate pendulum clock was invented by Huygens.

1350 Around this time the first blast furnaces for smelting iron from its ore begin to appear in Europe, 1800 years after the Chinese were using the technique.

See more about Cast Iron and Steel.

1368-1644 China's Ming dynasty. When the Ming dynasty came into power, China was the most advanced nation on Earth. During the Dark Ages in Europe, China had already developed cast iron, the compass, gunpowder, rockets, paper, paper money, canals and locks, block printing and moveable type, porcelain, pasta and many other inventions centuries before they were "invented" by the Europeans. From the first century B.C. they had also been using deep drilling to extract petroleum from the underlying rocks. They were so far ahead of Europe that when Marco Polo described these wondrous inventions in 1295 on his return to Venice from China he was branded a liar. China's innovation was based on practical inventions founded on empirical studies, but their inventiveness seems to have deserted them during the Ming dynasty and subsequently during the Qing (Ching) dynasty (1644 - 1911). China never developed a theoretical science base and both the Western scientific and industrial revolutions passed China by. Why should this be?

It is said that the answer lies in Chinese culture, to some extent Confucianism but particularly Daoism (Taoism) whose teachings promoted harmony with nature whereas Western aspirations were the control of nature. However these conditions existed before the Ming when China's innovation led the world. A more likely explanation can be found in China's imperial political system in which a massive society was rigidly controlled by all-powerful emperors through a relatively small cadre of professional administrators (Mandarins) whose qualifications were narrowly based on their knowledge of Confucian ideals. If the emperor was interested in something, it happened, if he wasn't, it didn't happen.

The turning point in China's technological dominance came when the Ming emperor Xuande came to power in 1426. Admiral Zheng He, a muslim eunuch, castrated as a boy when the Chinese conquered his tribe, had recently completed an audacious voyage of exploration on behalf of a previous Ming emperor Yongle to assert China's control of all of the known world and to extract tributary from its intended subjects. But his new master considered the benefits did not justify the huge expense of Zheng's fleet of 62 enormous nine masted junks and 225 smaller supply ships with their 27,000 crew. The emperor mothballed the fleet and henceforth forbade the construction of any ships with more than two masts, curbing China's aspirations as a maritime power and putting an end to its expansionist goals, a xenophobic policy which has lasted until modern times.

The result was that during both the Ming and the Qing dynasties a succession of complacent, conservative emperors cocooned in prodigious, obscene wealth, remote even from their own subjects, lived in complete isolation and ignorance of the rest of the world. Foreign influences, new ideas, and an independent merchant class who sponsored them, threatened their power and were consequently suppressed. By contrast the West was populated by smaller, diverse and independent nations competing with each other. Merchant classes were encouraged and innovation flourished as each struggled to gain competitive or military advantage.

Times have changed. Currently China is producing two million graduates per year, sixty percent of which are in science and technology subjects, three times as many as in the USA.

After Japan, China is the second largest battery producer in the world and growing fast.

1450 German goldsmith and calligrapher Johann Genstleisch zum Gutenberg from Mainz invented the printing press, considered to be one of the most important inventions in human history. For the first time knowledge and ideas could be recorded and disseminated to a much wider public than had previously been possible using hand written texts and its use spread rapidly throughout Europe. Intellectual life was no longer the exclusive domain of the church and the court and an era of enlightenment was ushered in with science, literature, religious and political texts becoming available to the masses who in turn had the facility to publish their own views challenging the status quo. It was the ability to publish and spread one's ideas that enabled the Scientific Revolution to happen. Nowadays the Internet is bringing about a similar revolution.

Although it was new to Europe, the Chinese had already invented printing with moveable type four hundred years earlier but, because of China's isolation, these developments never reached Europe.

Gutenberg printed Bibles and supported himself by printing indulgences, slips of paper sold by the Catholic Church to secure remission of the temporal punishments in Purgatory for sins committed in this life. He was a poor businessman and made little money from his printing system and depended on subsidies from the Archbishop of Mainz. Because he spent what little money he had on alcohol, the Archbishop arranged for him to be paid in food and lodging, instead of cash. Gutenberg died penniless in 1468.

1474 The first patent law, a statute issued by the Republic of Venice, provided for the grant of exclusive rights for limited periods to the makers of inventions. It was a law designed more to protect the economy of the state than the rights of the inventor since, as the result of its declining naval power, Venice was changing its focus from trading to manufacturing. The Republic required to be informed of all new and inventive devices, once they had been put into practice, so that they could take action against potential infringers.

1478 After 10 years working as an apprentice and assistant to successful Florentine artist Andrea del Verrocchio at the court of Lorenzo de Medici in Florence, at the age of 26 Leonardo da Vinci left the studio and began to accept commissions on his own.

One of the most brilliant minds of the Italian Renaissance, Leonardo was hugely talented as an artist and sculptor but also immensely creative as an engineer, scientist and inventor. The fame of his surviving paintings has meant that he has been regarded primarily as an artist, but his scientific insights were far ahead of their time. He investigated anatomy, geology, botany, hydraulics, acoustics, optics, mathematics, meteorology, and mechanics and his inventions included military machines, flying machines, and numerous hydraulic and mechanical devices.

He lived in an age of political in-fighting and intrigue between the independent Italian states of Rome, Milan, Florence, Venice and Naples as well as lesser players Genoa, Siena, and Mantua ever threatening to degenerate into all out war, in addition to threats of invasion from France. In those turbulent times da Vinci produced a series of drawings depicting possible weapons of war during his first two years as an independent. Thus began a lifelong fascination with military machines and mechanical devices which became an important part of his expanding portfolio and the basis for many of his offers to potential patrons, the heads of these belligerent, or fearful, independent states.

Despite his continuing interest in war machines, he claimed he was not a war monger and he recorded several times in his notebooks his discomfort with designing killing machines. Nevertheless, he actively solicited such commissions because by then he had his own pupils and needed the money to pay them.

Most of Leonardo's designs were not constructed in his lifetime and we only know about them through the many models he made but mostly from the 13,000 pages of notes and diagrams he made in which he recorded his scientific observations and sketched ideas for future paintings, architecture, and inventions. Unlike academics today who rush into publication, he never published any of his scientific works, fearing that others would steal his ideas. Patent law was still in its infancy and difficult, if not impossible, to enforce. Such was his paranoia about plagiarism that he even wrote all of his notes, back to front, in mirror writing, sometimes also in code, so he could keep his ideas private. He was not however concerned about keeping the notes secret after his death and in his will he left all his manuscripts, drawings, instruments and tools to his loyal pupil, Francesco Melzi with no objection to their publication. Melzi expected to catalogue and publish all of Leonardo's works but he was overwhelmed by the task, even with the help of two full-time scribes, and left only one incomplete volume, "Trattato della Pintura" or "Treatise on Painting", about Leonardo's paintings before he himself died in 1570. On his death the notes were inherited by his son Orazio who had no particular interest in the works and eventually sections of the notes were sold off piecemeal to treasure seekers and private collectors who were interested more in Leonardo's art rather than his science.

Because of his secrecy, his contemporaries knew nothing of his scientific works which consequently had no influence on the scientific revolution which was just beginning to stir. It was about two centuries before the public and the scientific community began gradually to get access to Leonardo's scientific notes when some collectors belatedly allowed them to be published or when they ended up on public display in museums where they became the inspiration for generations of inventors. Unfortunately, only 7000 pages are known to survive and over 6000 pages of these priceless notebooks have been lost forever. Who knows what wisdom they may have contained?

Leonardo da Vinci is now remembered as both "Leonardo the Artist" and "Leonardo the Scientist" but perhaps "Leonardo the Inventor" would be more apt as we shall see below.

Leonardo the Artist

It would not do justice to Leonardo to mention only his scientific achievements without mentioning his talent as a painter. His true genius was not as a scientist or an artist, but as a combination of the two: an "artist-engineer".

He did not sign his paintings and only 24 of his paintings are known to exist plus a further 6 paintings whose authentication is disputed. He did however make hundreds of drawings most of which were contained in his copious notes.

The "Treatise on Painting" This was the volume of Leonardo's manuscripts transcribed and compiled by Melzi. The engravings needed for reproducing Leonardo's original drawings were made by another famous painter, Nicolas Poussin. As the title suggests it was intended as technical manual for artists however it does contain some scientific notes about light, shade and optics in so far as they affect art and painting. For the same reason it also contains a small section of Leonardo's scientific works about anatomy. The publication of this volume in 1651 was the first time examples of the contents of Leonardo's notebooks were revealed to the world but it was 132 years after his death. The full range of his "known" scientific work was only made public little by little many years later.

Leonardo was one of the world's greatest artists, the few paintings he made were unsurpassed and his draughtsmanship had a photographic quality. Just seven examples of his well known artworks are mentioned here.

Paintings

The "Adoration of the Magi" painted in 1481.



The "Virgin of the Rocks" painted in 1483.



"The Last Supper" a large mural 29 feet long by 15 feet high (8.8 m x 4.6 m) started in 1495 which took him three years to complete.



The "Mona Lisa" (La Gioconda) painted in 1503.



"John the Baptist" painted in 1515.

Drawings

The "Vitruvian Man" as described by the Roman architect Vitruvius was drawn in 1490, showing the correlation between the proportions of the ideal human body with geometry, linking art and science in a single work.

was drawn in 1490, showing the correlation between the proportions of the ideal human body with geometry, linking art and science in a single work.

Illustrations for mathematician Fra Luca Pacioli's book "De divina proportione" (The Divine Proportion), drawn in 1496. See more about The Divine Proportion.

Leonardo the Scientist

The following are some examples of the extraordinary breadth of da Vinci's scientific works

Military Machines

After serving his apprenticeship with Verrocchio, Leonardo had a continuous flow of military commissions throughout his working life. In 1481 he wrote to Ludovico Sforza, Duke of Milan with a detailed C. V. of his military engineering skills, offering his services as military engineer, architect and sculptor and was appointed by him the following year. In 1502 the ruthless and murderous Cesare Borgia, illegitimate son of Pope Alexander VI and seducer of his own younger sister (Lucrezia Borgia), appointed Leonardo as military engineer to his court where he became friends with Niccolo Machiavelli, Borgia's influential advisor. In 1507 some time after France had invaded and occupied Milan he accepted the post of painter and engineer to King Louis XII of France in Milan and finally in 1517 he moved to France at the invitation of King Francoise I to take up the post of First Painter, Engineer and Architect of the King. These commissions gave Leonardo ample scope to develop his interest in military machines.

Leonardo designed war machines for both offensive and defensive use. They were designed to provide mobility and flexibility on the battlefield which he believed was crucial to victory. He also designed machines to use gunpowder which was still in its infancy in the fifteenth century.

His military inventions included: Mobile bridges including drawbridges and a swing bridge for crossing moats, ditches and rivers. His swing bridge was a cantilever design with a pivot on the river bank a counterweight to facilitate manoeuvring the span over the river. It also had wheels and a rope-and-pulley system which enabled easy transport and quick deployment.

including drawbridges and a for crossing moats, ditches and rivers. His swing bridge was a cantilever design with a pivot on the river bank a counterweight to facilitate manoeuvring the span over the river. It also had wheels and a rope-and-pulley system which enabled easy transport and quick deployment.

Siege machines for storming walls.

for storming walls.

Chariots with scythes mounted on the sides to cut down enemy troops.

mounted on the sides to cut down enemy troops.

A giant crossbow intended to fire large explosive projectiles several hundred yards.

intended to fire large explosive projectiles several hundred yards.

Trebuchets - Very large catapults , based on releasing mechanical counterweights, for flinging heavy projectiles into enemy fortifications.

- Very large , based on releasing mechanical counterweights, for flinging heavy projectiles into enemy fortifications.

Bombards - Short barrelled, large-calibre, muzzle-loading, heavy siege cannon or mortars , fired by gunpowder and used for throwing heavy stone balls. The modern replacement for the trebuchet. Leonardo's design had adjustable elevation. He also envisaged exploding cannonballs, made up from several smaller stone cannonballs sewn into spherical leather sacks and designed to injure and kill many enemies at one time. We would now call these cluster bombs .

- Short barrelled, large-calibre, muzzle-loading, heavy siege or , fired by gunpowder and used for throwing heavy stone balls. The modern replacement for the trebuchet. Leonardo's design had adjustable elevation. He also envisaged exploding cannonballs, made up from several smaller stone cannonballs sewn into spherical leather sacks and designed to injure and kill many enemies at one time. We would now call these .

Springalds - Smaller, more versatile cannon, for throwing stones or Greek fire, with variable azimuth and elevation adjustment so that they could be aimed more precisely.

- Smaller, more versatile cannon, for throwing stones or Greek fire, with variable azimuth and elevation adjustment so that they could be aimed more precisely.

A series of guns and cannons with multiple barrels. The forerunners of machine guns .

.

They included a triple barrelled cannon and an eight barrelled gun with eight muskets mounted side by side as well as a 33 barrelled version with three banks of eleven muskets designed to enable one set of eleven guns to be fired while a second set cooled off and a third set was being reloaded. The banks were arranged in the form of a triangle with a shaft passing through the middle so that the banks could be rotated to bring the loaded set to the top where it could be fired again. A four wheeled armoured tank with a heavy protective cover reinforced with metal plates similar to a turtle or tortoise shell with 36 large fixed cannons protruding from underneath. Inside a crew of eight men operating cranks geared to the wheels would drive the tank into battle. The drawing in Leonardo's notebook contains a curious flaw since the gearing would cause the front wheels to move in the opposite direction from the rear wheels. If the tank was built as drawn, it would have been unable to move. It is possible that this simple error would have escaped Leonardo's inventive mind but it is also suggested that like his coded notes, it was a deliberate fault introduced to confuse potential plagiarists. The idea that this armoured tank loaded with 36 heavy cannons in such a confined space could be both operated and manoeuvred by eight men is questionable.

with a heavy protective cover reinforced with metal plates similar to a turtle or tortoise shell with 36 large fixed cannons protruding from underneath. Inside a crew of eight men operating cranks geared to the wheels would drive the tank into battle. The drawing in Leonardo's notebook contains a curious flaw since the gearing would cause the front wheels to move in the opposite direction from the rear wheels. If the tank was built as drawn, it would have been unable to move. It is possible that this simple error would have escaped Leonardo's inventive mind but it is also suggested that like his coded notes, it was a deliberate fault introduced to confuse potential plagiarists. The idea that this armoured tank loaded with 36 heavy cannons in such a confined space could be both operated and manoeuvred by eight men is questionable.

Automatic igniting device for firearms.

for firearms. Marine Warfare Machines and Devices

Leonardo also designed machines for naval warfare including: Designs for a peddle driven paddle boat . The forerunner of the modern pedalo .

. The forerunner of the modern .

Hand flippers and floats for walking on water.

for walking on water.

Diving suit to enable enemy vessels to be attacked from beneath the water's surface by divers cutting holes below the boat's water line. It consisted of a leather diving suit equipped with a bag-like helmet fitting over the diver's head. Air was supplied to the diver by means of two cane tubes attached to the headgear which led up to a cork diving bell floating on the surface.

to enable enemy vessels to be attacked from beneath the water's surface by divers cutting holes below the boat's water line. It consisted of a leather diving suit equipped with a bag-like helmet fitting over the diver's head. Air was supplied to the diver by means of two cane tubes attached to the headgear which led up to a cork diving bell floating on the surface.

A double hulled ship which could survive the exterior skin being pierced by ramming or underwater attack, a safety feature which was eventually adopted in the nineteenth century.

which could survive the exterior skin being pierced by ramming or underwater attack, a safety feature which was eventually adopted in the nineteenth century.

An armoured battleship similar to the armoured tank which could ram and sink enemy ships.

similar to the armoured tank which could ram and sink enemy ships.

Barrage cannon - a large floating circular platform with 16 canons mounted around its periphery. It was powered and steered by two operators turning drive wheels geared to a large central drive wheel connected to paddles for propelling it through the water. Others operators fired the cannons.

- a large floating circular platform with 16 canons mounted around its periphery. It was powered and steered by two operators turning drive wheels geared to a large central drive wheel connected to paddles for propelling it through the water. Others operators fired the cannons. Flying Machines

Leonardo studied the flight of birds and after the legendary Icarus was one of the first to attempt to design human powered flying machines, recording his ideas in numerous drawings. A step up from Chinese kites. His drawings included: A design for a parachute . The world's first.

. The world's first.

Various gliders



Designs for wings intended to carry a man aloft, similar to scaled up bat wings.

intended to carry a man aloft, similar to scaled up bat wings.

Human powered flying machines known as ornithopters , (from Greek ornithos "bird" and pteron "win