Hero of Alexandria (; grc-gre, Ἥρων ὁ Ἀλεξανδρεύς, ''Heron ho Alexandreus'', also known as Heron of Alexandria ; 60 AD) was a
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
mathematician
A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems.
Mathematicians are concerned with numbers, data, quantity, structure, space, models, and change.
History
On ...
and
engineer
Engineers, as practitioners of engineering, are professionals who invent, design, analyze, build and test machines, complex systems, structures, gadgets and materials to fulfill functional objectives and requirements while considering the l ...
who was active in his native city of
Alexandria
Alexandria ( or ; ar, ٱلْإِسْكَنْدَرِيَّةُ ; grc-gre, Αλεξάνδρεια, Alexándria) is the second largest city in Egypt, and the largest city on the Mediterranean coast. Founded in by Alexander the Great, Alexandria ...
,
Roman Egypt
, conventional_long_name = Roman Egypt
, common_name = Egypt
, subdivision = Province
, nation = the Roman Empire
, era = Late antiquity
, capital = Alexandria
, title_leader = Praefectus Augustalis
, image_map = Roman E ...
. He is often considered the greatest experimenter of antiquity
and his work is representative of the
Hellenistic
In Classical antiquity, the Hellenistic period covers the time in Mediterranean history after Classical Greece, between the death of Alexander the Great in 323 BC and the emergence of the Roman Empire, as signified by the Battle of Actium in ...
scientific tradition.
Hero published a well-recognized description of a
steam-powered device called an ''
aeolipile
An aeolipile, aeolipyle, or eolipile, from the Greek "αιολουπυλη", also known as a Hero's engine, is a simple, bladeless radial steam turbine which spins when the central water container is heated. Torque is produced by steam jets exi ...
'' (sometimes called a "Hero engine"). Among his most famous inventions was a
windwheel, constituting the earliest instance of
wind harnessing on land.
He is said to have been a follower of the
atomists
Atomism (from Greek , ''atomon'', i.e. "uncuttable, indivisible") is a natural philosophy proposing that the physical universe is composed of fundamental indivisible components known as atoms.
References to the concept of atomism and its atoms a ...
. In his work ''Mechanics'', he described
pantograph
A pantograph (, from their original use for copying writing) is a mechanical linkage connected in a manner based on parallelograms so that the movement of one pen, in tracing an image, produces identical movements in a second pen. If a line dr ...
s. Some of his ideas were derived from the works of
Ctesibius
Ctesibius or Ktesibios or Tesibius ( grc-gre, Κτησίβιος; fl. 285–222 BC) was a Greek inventor and mathematician in Alexandria, Ptolemaic Egypt. He wrote the first treatises on the science of compressed air and its uses in pumps (a ...
.
In mathematics he is mostly remembered for
Heron's formula
In geometry, Heron's formula (or Hero's formula) gives the area of a triangle in terms of the three side lengths , , . If s = \tfrac12(a + b + c) is the semiperimeter of the triangle, the area is,
:A = \sqrt.
It is named after first-century ...
, a way to calculate the area of a triangle using only the lengths of its sides.
Much of Hero's original writings and designs have been
lost
Lost may refer to getting lost, or to:
Geography
*Lost, Aberdeenshire, a hamlet in Scotland
* Lake Okeechobee Scenic Trail, or LOST, a hiking and cycling trail in Florida, US
History
*Abbreviation of lost work, any work which is known to have bee ...
, but some of his works were preserved including in manuscripts from the Eastern Roman Empire and to a lesser extent, in Latin or Arabic translations.
Life and career
Hero's ethnicity may have been either
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
or
Hellenized
Hellenization (other British spelling Hellenisation) or Hellenism is the adoption of Greek culture, religion, language and identity by non-Greeks. In the ancient period, colonization often led to the Hellenization of indigenous peoples; in th ...
Egyptian
Egyptian describes something of, from, or related to Egypt.
Egyptian or Egyptians may refer to:
Nations and ethnic groups
* Egyptians, a national group in North Africa
** Egyptian culture, a complex and stable culture with thousands of years of ...
. It is almost certain that Hero taught at the
Musaeum
The Musaeum or Mouseion of Alexandria ( grc, Μουσεῖον τῆς Ἀλεξανδρείας; ), which arguably included the Great Library of Alexandria, was an institution said to have been founded by Ptolemy I Soter and his son Ptolemy II P ...
which included the famous
Library of Alexandria
The Great Library of Alexandria in Alexandria, Egypt, was one of the largest and most significant libraries of the ancient world. The Library was part of a larger research institution called the Mouseion, which was dedicated to the Muses, th ...
, because most of his writings appear as lecture notes for courses in
mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
,
mechanics
Mechanics (from Ancient Greek: μηχανική, ''mēkhanikḗ'', "of machines") is the area of mathematics and physics concerned with the relationships between force, matter, and motion among physical objects. Forces applied to objects r ...
,
physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
and
pneumatics
Pneumatics (from Greek ‘wind, breath’) is a branch of engineering that makes use of gas or pressurized air.
Pneumatic systems used in industry are commonly powered by compressed air or compressed inert gases. A centrally located and elec ...
. Although the field was not formalized until the twentieth century, it is thought that the work of Hero, in particular his automated devices, represented some of the first formal research into
cybernetics
Cybernetics is a wide-ranging field concerned with circular causality, such as feedback, in regulatory and purposive systems. Cybernetics is named after an example of circular causal feedback, that of steering a ship, where the helmsperson m ...
.
Inventions
Hero described the construction of the ''
aeolipile
An aeolipile, aeolipyle, or eolipile, from the Greek "αιολουπυλη", also known as a Hero's engine, is a simple, bladeless radial steam turbine which spins when the central water container is heated. Torque is produced by steam jets exi ...
'' (a version of which is known as ''Hero's engine'') which was a
rocket-like reaction engine and the first-recorded
steam engine
A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force can be trans ...
(although
Vitruvius
Vitruvius (; c. 80–70 BC – after c. 15 BC) was a Roman architect and engineer during the 1st century BC, known for his multi-volume work entitled ''De architectura''. He originated the idea that all buildings should have three attribute ...
mentioned the aeolipile in ''
De Architectura
(''On architecture'', published as ''Ten Books on Architecture'') is a treatise on architecture written by the Roman architect and military engineer Marcus Vitruvius Pollio and dedicated to his patron, the emperor Caesar Augustus, as a guide f ...
'' some 100 years earlier than Hero). It was described almost two millennia before the
industrial revolution
The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...
. Another engine used air from a closed chamber heated by an altar fire to displace water from a sealed vessel; the water was collected and its weight, pulling on a rope, opened temple doors. Some historians have conflated the two inventions to assert that the aeolipile was capable of useful work, which is not entirely false, air containing a trace of water vapor. However, this engine is far from a pure aeolipile.
* The first
vending machine
A vending machine is an automated machine that provides items such as snacks, beverages, cigarettes, and lottery tickets to consumers after cash, a credit card, or other forms of payment are inserted into the machine or otherwise made. The fir ...
was also one of his constructions; when a coin was introduced via a slot on the top of the machine, a set amount of holy water was dispensed. This was included in his list of inventions in his book ''Mechanics and Optics''. When the coin was deposited, it fell upon a pan attached to a lever. The lever opened up a valve which let some water flow out. The pan continued to tilt with the weight of the coin until it fell off, at which point a counter-weight would snap the lever back up and turn off the valve.
* A wind-wheel operating an organ, marking the first instance in history of wind powering a machine.
[A.G. Drachmann, "Heron's Windmill", ''Centaurus'', 7 (1961), pp. 145–151][Dietrich Lohrmann, "Von der östlichen zur westlichen Windmühle", ''Archiv für Kulturgeschichte'', Vol. 77, Issue 1 (1995), pp. 1–30 (10f.)]
* Hero also invented many mechanisms for the Greek
theatre
Theatre or theater is a collaborative form of performing art that uses live performers, usually actors or actresses, to present the experience of a real or imagined event before a live audience in a specific place, often a stage. The perform ...
, including an entirely mechanical play almost ten minutes in length, powered by a binary-like system of ropes, knots, and simple machines operated by a rotating cylindrical cogwheel. The sound of
thunder
Thunder is the sound caused by lightning. Depending upon the distance from and nature of the lightning, it can range from a long, low rumble to a sudden, loud crack. The sudden increase in temperature and hence pressure caused by the lightning pr ...
was produced by the mechanically-timed dropping of metal balls onto a hidden drum.
* The
force pump
A piston pump is a type of positive displacement pump where the high-pressure seal reciprocates with the piston. Piston pumps can be used to move liquids or compress gases. They can operate over a wide range of pressures. High pressure operatio ...
was widely used in the
Roman
Roman or Romans most often refers to:
*Rome, the capital city of Italy
*Ancient Rome, Roman civilization from 8th century BC to 5th century AD
*Roman people, the people of ancient Rome
*''Epistle to the Romans'', shortened to ''Romans'', a letter ...
world, and one application was in a fire-engine.
* A
syringe
A syringe is a simple reciprocating pump consisting of a plunger (though in modern syringes, it is actually a piston) that fits tightly within a cylindrical tube called a barrel. The plunger can be linearly pulled and pushed along the inside ...
-like device was described by Hero to control the delivery of air or liquids.
* In optics, Hero formulated the
principle of the shortest path of light: If a ray of light propagates from point A to point B within the same medium, the path-length followed is the shortest possible. It was nearly 1,000 years later that
Alhacen
Ḥasan Ibn al-Haytham, Latinized as Alhazen (; full name ; ), was a medieval mathematician, astronomer, and physicist of the Islamic Golden Age from present-day Iraq.For the description of his main fields, see e.g. ("He is one of the prin ...
expanded the principle to both reflection and refraction, and the principle was later stated in this form by
Pierre de Fermat
Pierre de Fermat (; between 31 October and 6 December 1607 – 12 January 1665) was a French mathematician who is given credit for early developments that led to infinitesimal calculus, including his technique of adequality. In particular, he ...
in 1662; the most modern form is that the optical path is
stationary.
* A stand-alone fountain that operates under self-contained hydro-static energy; now called
Heron's fountain
Heron's fountain is a hydraulic machine invented by the 1st century AD inventor, mathematician, and physicist Heron of Alexandria (also known as Hero of Alexandria).
Heron studied the pressure of air and steam, described the first steam engin ...
.
* A cart that was powered by a falling weight and strings wrapped around the drive axle.
* Various authors have credited the invention of the
thermometer
A thermometer is a device that temperature measurement, measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a merc ...
to Hero. The thermometer was
not a single invention, however, but a development. Hero knew of the principle that certain substances, notably air, expand and contract and described a demonstration in which a closed tube partially filled with air had its end in a container of water. The expansion and contraction of the air caused the position of the water/air interface to move along the tube.
* A self-filling wine bowl, using a
float valve
A ballcock (also balltap or float valve) is a mechanism or machine for filling water tanks, such as those found in flush toilets, while avoiding overflow and (in the event of low water pressure) backflow. The modern ballcock was invented by Jos ...
.
Mathematics
Hero described a method (now known as
Heron's method), for iteratively computing the
square root
In mathematics, a square root of a number is a number such that ; in other words, a number whose ''square'' (the result of multiplying the number by itself, or ⋅ ) is . For example, 4 and −4 are square roots of 16, because .
E ...
of a number. Today, however, his name is most closely associated with
Heron's formula
In geometry, Heron's formula (or Hero's formula) gives the area of a triangle in terms of the three side lengths , , . If s = \tfrac12(a + b + c) is the semiperimeter of the triangle, the area is,
:A = \sqrt.
It is named after first-century ...
for finding the area of a triangle from its side lengths. He also devised a method for calculating cube roots. He also designed a shortest path algorithm, that is, given two points A and B on one side of a line, find C a point on the straight line that minimizes AC+BC.
In
solid geometry
In mathematics, solid geometry or stereometry is the traditional name for the geometry of Three-dimensional space, three-dimensional, Euclidean spaces (i.e., 3D geometry).
Stereometry deals with the measurements of volumes of various solid fig ...
, the
Heronian mean In mathematics, the Heronian mean ''H'' of two non-negative real numbers ''A'' and ''B'' is given by the formula:
:H = \frac \left(A + \sqrt +B \right).
It is named after Hero of Alexandria.
Properties
*Just like all means, the Heronian mean is ...
may be used in finding the
volume
Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). The de ...
of a
frustum
In geometry, a (from the Latin for "morsel"; plural: ''frusta'' or ''frustums'') is the portion of a solid (normally a pyramid or a cone) that lies between two parallel planes cutting this solid. In the case of a pyramid, the base faces are ...
of a
pyramid
A pyramid (from el, πυραμίς ') is a structure whose outer surfaces are triangular and converge to a single step at the top, making the shape roughly a pyramid in the geometric sense. The base of a pyramid can be trilateral, quadrilat ...
or
cone
A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the apex or vertex.
A cone is formed by a set of line segments, half-lines, or lines con ...
.
Cultural references
*In
Arthur C. Clarke's 1953 novel ''
Childhood's End
''Childhood's End'' is a 1953 science fiction novel by the British author Arthur C. Clarke. The story follows the peaceful alien invasionBooker & Thomas 2009, pp. 31–32. of Earth by the mysterious Overlords, whose arrival begins decade ...
'', a model of the turbine is present in the Earth exhibit of the Overlords' museum of alien cultures.
*A 1979 Soviet animated short film focuses on Hero's invention of the ''aeolipile'', showing him as a plain craftsman who invented the
turbine
A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced by a turbine can be used for generating e ...
accidentally
Bibliography
![Hero - De automatis, 1589 - 116959](https://upload.wikimedia.org/wikipedia/commons/0/01/Hero_-_De_automatis%2C_1589_-_116959.jpg)
The most comprehensive edition of Hero's works was published in five volumes in Leipzig by the publishing house Teubner in 1903.
Works known to have been written by Hero include:
*''Pneumatica'' (Πνευματικά), a description of machines working on
air
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...
,
steam
Steam is a substance containing water in the gas phase, and sometimes also an aerosol of liquid water droplets, or air. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization ...
or
water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...
pressure
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...
, including the ''hydraulis'' or
water organ
The water organ or hydraulic organ ( el, ὕδραυλις) (early types are sometimes called hydraulos, hydraulus or hydraula) is a type of pipe organ blown by air, where the power source pushing the air is derived by water from a natural source ...
*''Automata'', a description of machines which enable wonders in banquets and possibly also theatrical contexts by mechanical or pneumatical means (e.g. automatic opening or closing of temple doors, statues that pour wine and milk, etc.)
*''Mechanica'', preserved only in Arabic, written for
architect
An architect is a person who plans, designs and oversees the construction of buildings. To practice architecture means to provide services in connection with the design of buildings and the space within the site surrounding the buildings that h ...
s, containing means to lift heavy objects
*''Metrica'', a description of how to calculate
surface
A surface, as the term is most generally used, is the outermost or uppermost layer of a physical object or space. It is the portion or region of the object that can first be perceived by an observer using the senses of sight and touch, and is ...
s and
volume
Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). The de ...
s of diverse objects
*''On the Dioptra'', a collection of methods to measure lengths, a work in which the
odometer
An odometer or odograph is an instrument used for measuring the distance traveled by a vehicle, such as a bicycle or car. The device may be electronic, mechanical, or a combination of the two (electromechanical). The noun derives from ancient Gr ...
and the
dioptra
A dioptra (sometimes also named dioptre or diopter, from el, διόπτρα) is a classical astronomical and surveying instrument, dating from the 3rd century BC. The dioptra was a sighting tube or, alternatively, a rod with a sight at ...
, an apparatus which resembles the
theodolite
A theodolite () is a precision optical instrument for measuring angles between designated visible points in the horizontal and vertical planes. The traditional use has been for land surveying, but it is also used extensively for building and i ...
, are described
*''Belopoeica'', a description of
war machines
*''Catoptrica'', about the progression of
light
Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 tera ...
,
reflection Reflection or reflexion may refer to:
Science and technology
* Reflection (physics), a common wave phenomenon
** Specular reflection, reflection from a smooth surface
*** Mirror image, a reflection in a mirror or in water
** Signal reflection, in ...
and the use of
mirror
A mirror or looking glass is an object that Reflection (physics), reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the ...
s
Works that sometimes have been attributed to Hero, but are now thought most likely to have been written by someone else:
*''Geometrica'', a collection of equations based on the first chapter of ''Metrica''
*''Stereometrica'', examples of three-dimensional calculations based on the second chapter of ''Metrica''
*''Mensurae'', tools which can be used to conduct measurements based on ''Stereometrica'' and ''Metrica''
*''Cheiroballistra'', about
catapult
A catapult is a ballistic device used to launch a projectile a great distance without the aid of gunpowder or other propellants – particularly various types of ancient and medieval siege engines. A catapult uses the sudden release of stored p ...
s
*''Definitiones'', containing definitions of terms for geometry
Works that are preserved only in fragments:
*''Geodesia''
*''Geoponica''
Publications
*
See also
*
Heronian triangle
In geometry, a Heronian triangle (or Heron triangle) is a triangle whose side lengths , , and and area are all integers. Heronian triangles are named after Heron of Alexandria, based on their relation to Heron's formula.
Heron's formula implies ...
*
Heronian mean In mathematics, the Heronian mean ''H'' of two non-negative real numbers ''A'' and ''B'' is given by the formula:
:H = \frac \left(A + \sqrt +B \right).
It is named after Hero of Alexandria.
Properties
*Just like all means, the Heronian mean is ...
References
Further reading
*
*
*
*
External links
Webpage about Hero by The Technology Museum of Thessalonikiat the
MacTutor History of Mathematics archive
The MacTutor History of Mathematics archive is a website maintained by John J. O'Connor and Edmund F. Robertson and hosted by the University of St Andrews in Scotland. It contains detailed biographies on many historical and contemporary mathemati ...
*
Heron of Alexandriain online
Encyclopædia Britannica
The (Latin for "British Encyclopædia") is a general knowledge English-language encyclopaedia. It is published by Encyclopædia Britannica, Inc.; the company has existed since the 18th century, although it has changed ownership various time ...
Online Galleries, History of Science Collections, University of Oklahoma LibrariesHigh resolution images preserved at The
Internet Archive
The Internet Archive is an American digital library with the stated mission of "universal access to all knowledge". It provides free public access to collections of digitized materials, including websites, software applications/games, music, ...
*
Reconstruction of Heron’s Formulas for Calculating the Volume of VesselsSpiritali di Herone AlessandrinoFrom th
at the
Library of Congress
The Library of Congress (LOC) is the research library that officially serves the United States Congress and is the ''de facto'' national library of the United States. It is the oldest federal cultural institution in the country. The library is ...
AutomataCritical edition, with translation and partial commentary by Francesco Grillo (PhD thesis, Univ. of Glasgow, 2019)
The Pneumatics of Hero of Alexandria, from the Original Greek. Tr. and ed. by Bennet WoodcroftFrom the Collections at the
Library of Congress
The Library of Congress (LOC) is the research library that officially serves the United States Congress and is the ''de facto'' national library of the United States. It is the oldest federal cultural institution in the country. The library is ...
{{DEFAULTSORT:Hero Of Alexandria
AD 10 births
70 deaths
1st-century Egyptian people
1st-century Greek people
1st-century writers
Ancient Egyptian engineers
Ancient Greek engineers
Ancient Greek inventors
Ancient Greek geometers
Ancient Greek science writers
Egyptian inventors
Egyptian people of Greek descent
Hellenistic engineers
Roman-era Alexandrians
1st-century mathematicians