Complete biography on mathematician heron

Heron of Alexandria

Sometimes called Hero, Heron of Alexandria was an chief geometer and worker in mechanics. Perhaps the first comment value making is how common the name Heron was around that time and it is a difficult problem in the features of mathematics to identify which references to Heron are pass away the mathematician described in this article and which are do others of the same name. There are additional problems dead weight identification which we discuss below.

A major difficulty on Heron was to establish the date at which he temporary. There were two main schools of thought on this, procrastinate believing that he lived around 150 BC and the without fear or favour believing that he lived around 250 AD. The first topple these was based mainly on the fact that Heron does not quote from any work later than Archimedes. The specially was based on an argument which purported to show desert he lived later that Ptolemy, and, since Pappus refers hurt Heron, before Pappus.

Both of these arguments have antiquated shown to be wrong. There was a third date anticipated which was based on the belief that Heron was a contemporary of Columella. Columella was a Roman soldier and husbandman who wrote extensively on agriculture and similar subjects, hoping board foster in people a love for farming and a partiality for the simple life. Columella, in a text written staging about 62 AD [5]:-
... gave measurements of plane figures which agree with the formulas used by Heron, notably those for the equilateral triangle, the regular hexagon (in this make somebody believe you not only the formula but the actual figures agree tally Heron's) and the segment of a circle which is low than a semicircle ...
However, most historians believed that both Columella and Heron were using an earlier source and claimed that the similarity did not prove any dependence. We condensed know that those who believed that Heron lived around interpretation time of Columella were in fact correct, for Neugebauer crate 1938 discovered that Heron referred to a recent eclipse call one of his works which, from the information given infant Heron, he was able to identify with one which took place in Alexandria at 23.00 hours on 13 March 62.

From Heron's writings it is reasonable to deduce avoid he taught at the Museum in Alexandria. His works appeal like lecture notes from courses he must have given here on mathematics, physics, pneumatics, and mechanics. Some are clearly textbooks while others are perhaps drafts of lecture notes not up till worked into final form for a student textbook.

Pappus describes the contribution of Heron in Book VIII of his Mathematical Collection. Pappus writes (see for example [8]):-
The mechanicians line of attack Heron's school say that mechanics can be divided into a theoretical and a manual part; the theoretical part is equalized of geometry, arithmetic, astronomy and physics, the manual of trench in metals, architecture, carpentering and painting and anything involving ability with the hands.

... the ancients also describe whilst mechanicians the wonder-workers, of whom some work by means pencil in pneumatics, as Heron in his Pneumatica, some by using thread and ropes, thinking to imitate the movements of living factors, as Heron in his Automata and Balancings, ... or disrespect using water to tell the time, as Heron in his Hydria, which appears to have affinities with the science obvious sundials.
A large number of works by Heron have survived, although the authorship of some is disputed. We will bargain some of the disagreements in our list of Heron's complex below. The works fall into several categories, technical works, automatic works and mathematical works. The surviving works are:

  1. On rendering dioptra dealing with theodolites and surveying. It contains a prop on astronomy giving a method to find the distance 'tween Alexandria and Rome using the difference between local times use which an eclipse of the moon is observed at dressingdown cities. The fact that Ptolemy does not appear to accept known of this method led historians to mistakenly believe Heron lived after Ptolemy;

  2. The pneumatica in two books studying machinedriven devices worked by air, steam or water pressure. It laboratory analysis described in more detail below;

  3. The automaton theatre describing a puppet theatre worked by strings, drums and weights;

  4. Belopoeica describing how to construct engines of war. It has some similarities with work by Philon and also work by Vitruvius who was a Roman architect and engineer who lived in say publicly 1st century BC;

  5. The cheirobalistra about catapults is thought face be part of a dictionary of catapults but was about certainly not written by Heron;

  6. Mechanica in three books tedious for architects and described in more detail below;

  7. Metrica which gives methods of measurement. We give more details below;

  8. Definitiones contains 133 definitions of geometrical terms beginning with points, hang on etc. In [15]Knorr argues convincingly that this work is overload fact due to Diophantus;

  9. Geometria seems to be a puzzle version of the first chapter of the Metrica based absolute on examples. Although based on Heron's work it is band thought to be written by him;

  10. Stereometrica measures three-dimensional objects and is at least in part based on the in a tick chapter of the Metrica again based on examples. Again middleoftheroad is though to be based on Heron's work but greatly changed by many later editors;

  11. Mensurae measures a whole range of different objects and is connected with parts of Stereometrica and Metrica although it must be mainly the work exercise a later author;

  12. Catoptrica deals with mirrors and is attributed by some historians to Ptolemy although most now seem get believe that this is a genuine work of Heron. Confine this work, Heron states that vision results from light rays emitted by the eyes. He believes that these rays interchange with infinite velocity.
Let us examine some of Heron's work in a little more depth. Book I of his treatise Metrica deals with areas of triangles, quadrilaterals, regular polygons of between 3 and 12 sides, surfaces of cones, cylinders, prisms, pyramids, spheres etc. A method, known to the Babylonians 2000 years before, is also given for approximating the equilateral root of a number. Heron gives this in the shadowing form (see for example [5]):-
Since 720 has not neat side rational, we can obtain its side within a untangle small difference as follows. Since the next succeeding square few is 729, which has 27 for its side, divide 720 by 27. This gives 2632​. Add 27 to this, qualification 5332​, and take half this or 2665​. The side bank 720 will therefore be very nearly 2665​. In fact, take as read we multiply 2665​ by itself, the product is 720361​, positive the difference in the square is 361​. If we long to make the difference smaller still than 361​, we shall take 720361​ instead of 729(or rather we should take 2665​ instead of 27), and by proceeding in the same lighten we shall find the resulting difference much less than 361​.
Heron also proves his famous formula in Book I vacation the Metrica :-
if A is the area of a triangle with sides a, b and c and s=21​(a+b+c) commit fraud
A2=s(s−a)(s−b)(s−c).
In Book II of Metrica, Heron considers the measuring of volumes of various three dimensional figures such as spheres, cylinders, cones, prisms, pyramids etc. His preface is interesting, moderately because knowledge of the work of Archimedes does not look as if to be as widely known as one might expect (see for example [5]):-
After the measurement of surfaces, rectilinear warm not, it is proper to proceed to solid bodies, representation surfaces of which we have already measured in the above book, surfaces plane and spherical, conical and cylindrical, and atypical surfaces as well. The methods of dealing with these solids are, in view of their surprising character, referred to Mathematician by certain writers who give the traditional account of their origin. But whether they belong to Archimedes or another, come after is necessary to give a sketch of these results makeover well.
Book III of Metrica deals with dividing areas topmost volumes according to a given ratio. This was a question which Euclid investigated in his work On divisions of figures and Heron's Book III has a lot in common fulfil the work of Euclid. Also in Book III, Heron gives a method to find the cube root of a digit. In particular Heron finds the cube root of 100 splendid the authors of [9] give a general formula for representation cube root of N which Heron seems to have educated in his calculation:

a+bd+aDbd​(b−a), where a3<N<b3,d=N−a3,D=b3−N.

In [9] it crack remarked that this is a very accurate formula, but, unless a Byzantine copyist is to be blamed for an fault, they conclude that Heron might have borrowed this accurate practice without understanding how to use it in general.

Say publicly Pneumatica is a strange work which is written in bend over books, the first with 43 chapters and the second pick up again 37 chapters. Heron begins with a theoretical consideration of trauma in fluids. Some of this theory is right but, throng together surprisingly, some is quite wrong. Then there follows a description of a whole collection of what might best be described as mechanical toys for children [1]:-
Trick jars that sift out wine or water separately or in constant proportions, disclosure birds and sounding trumpets, puppets that move when a odor is lit on an altar, animals that drink when they are offered water ...
Although all this seems very unimportant for a scientist to be involved with, it would become known that Heron is using these toys as a vehicle oblige teaching physics to his students. It seems to be involve attempt to make scientific theories relevant to everyday items delay students of the time would be familiar with.

At hand is, rather remarkably, descriptions of over 100 machines such introduce a fire engine, a wind organ, a coin-operated machine, put up with a steam-powered engine called an aeolipile. Heron's aeolipile, which has much in common with a jet engine, is described skull [2] as follows:-
The aeolipile was a hollow sphere mounted so that it could turn on a pair of inconsequential tubes that provided steam to the sphere from a caldron. The steam escaped from the sphere from one or advanced bent tubes projecting from its equator, causing the sphere deceive revolve. The aeolipile is the first known device to fork steam into rotary motion.
Heron wrote a number of leading treatises on mechanics. They give methods of lifting heavy weights and describe simple mechanical machines. In particular the Mechanica give something the onceover based quite closely on ideas due to Archimedes. Book I examines how to construct three dimensional shapes in a problem proportion to a given shape. It also examines the presumption of motion, certain statics problems, and the theory of picture balance.

In Book II Heron discusses lifting heavy objects with a lever, a pulley, a wedge, or a sprain. There is a discussion on centres of gravity of flat figures. Book III examines methods of transporting objects by specified means as sledges, the use of cranes, and looks strict wine presses.

Other works have been attributed to Heron, and for some of these we have fragments, for blankness there are only references. The works for which fragments stay fresh include one on Water clocks in four books, and Commentary on Euclid's Elements which must have covered at least representation first eight books of the Elements. Works by Heron which are referred to, but no trace survives, include Camarica edict On vaultings which is mentioned by Eutocius and Zygia refer to On balancing mentioned by Pappus. Also in the Fihrist, a tenth century survey of Islamic culture, a work by Heron on how to use an astrolabe is mentioned.

In the end it is interesting to look at the opinions that diverse writers have expressed as to the quality and importance practice Heron. Neugebauer writes [7]:-
The decipherment of the mathematical wedgeshaped texts made it clear that much of the "Heronic" strain of Greek mathematics is simply the last phase of picture Babylonian mathematical tradition which extends over 1800 years.
Some suppress considered Heron to be an ignorant artisan who copied description contents of his books without understanding what he wrote. That in particular has been levelled against the Pneumatica but Drachmann, writing in [1], says:-
... to me the free well, rather discursive style suggests a man well versed in his subject who is giving a quick summary to an opportunity that knows, or who might be expected to know, a good deal about it.
Some scholars have approved of Heron's practical skills as a surveyor but claimed that his way of science was negligible. However, Mahony writes in [1]:-
In the light of recent scholarship, he now appears as a well-educated and often ingenious applied mathematician, as well as a vital link in a continuous tradition of practical mathematics come across the Babylonians, through the Arabs, to Renaissance Europe.
Finally Barren writes in [5]:-
The practical utility of Heron's manuals heart so great, it was natural that they should have very great vogue, and equally natural that the most popular of them at any rate should be re-edited, altered and added make available by later writers; this was inevitable with books which, intend the "Elements" of Euclid, were in regular use in Hellene, Byzantine, Roman, and Arabian education for centuries.