Ptolemy scientist biography. Claudius Ptolemy: biography, creativity, career, personal life

The enduring significance of Ptolemy's theory is that it convincingly demonstrated the power of mathematics in rationally understanding complex and even mysterious physical phenomena.

Morris Kline

Claudius Ptolemy (c. 100 - c. 178) - Ancient Greek astronomer, astrologer, mathematician, mechanic, optician, music theorist and geographer. One of the most prominent scientists of antiquity. One of the progenitors of trigonometry.

Claudius Ptolemy is one of the major figures in the science of late Hellenism. In astronomy, Ptolemy had no equal for a whole millennium - from Hipparchus of Nicea (II century BC), the greatest astronomer of antiquity, to Al-Biruni (X-XI centuries AD), a great scientist from Khorezm, author of numerous capital works on history, geography, philology, astronomy, mathematics, mechanics, geodesy, mineralogy, pharmacology, geology.

History has treated the personality and works of Ptolemy in a rather strange way. There is no mention of his life and work in contemporary authors. In historical works of the first centuries AD, Claudius Ptolemy was sometimes associated with the Ptolemies, a dynasty of rulers of Egypt, but modern historians believe this to be an error due to the coincidence of names (the name Ptolemy was popular in the former kingdom of the Lagids). The Roman family name Claudius shows that Ptolemy was a Roman citizen, and his ancestors received Roman citizenship, most likely from the Emperor Claudius.

There is no evidence that Ptolemy lived or visited anywhere other than Alexandria. With a high degree of probability it can be said that Ptolemy was a Roman citizen of Greek origin who lived in Egypt.

The greatest fame for Claudius Ptolemy was brought to him by his astronomical works, including, first of all, “ Mathematical system"(Mathematike syntaksis) in 13 books, later called the "Great System" (Megale syntaksis), from which in Arabic, by adding the article al, the name "Almagest" was obtained, by which the work of Ptolemy is known everywhere. This work was the result of the development of ancient celestial mechanics and contained an almost complete collection of astronomical knowledge of Greece and the Middle East of that time.

In the Almagest, Ptolemy, using the works of his predecessors (mainly Hipparchus of Nicaea and Apollonius of Perga), not only brought together all the astronomical knowledge of antiquity, which he enriched with his own observations (made in 127 - 141), but gave the first systematic presentation of mathematical astronomy. Books I and II present the geocentric system, books IV-VI contain the lunar theory, books VII-VIII talk about the stars, the remaining books are devoted to the theory of planetary motion.

In this work, Ptolemy showed himself to be a skilled mechanic, since he was able to represent the uneven movements of the celestial bodies as a combination of several uniform movements in circles (epicycles, deferents, equants).

Almagest also contained a catalog starry sky. The list of 48 constellations did not cover the entire celestial sphere: there were only those stars that Ptolemy could see while in Alexandria.

This greatest work of Ptolemy was commented on by Pappus, Theon, Hypatia, Proclus. It was early translated into Arabic (the first translation dates back to the 8th-9th centuries), in this version it came to medieval Europe, where it was translated into Latin many times.

The Ptolemaic system was practically generally accepted in the Western and Arab world - until the creation of the heliocentric system of Nicolaus Copernicus.

Ptolemy also wrote about the theory of planets in his late work “Hypotheses of the Planets” (Hypotheseis ton planomenon), partially preserved in Arabic translation.

The question of the relationship between the works of Ptolemy and the works of more early authors. There is an assumption that Ptolemy's star catalog was an updated version of the catalog created earlier by Hipparchus. This version is supported by the fact that, according to the research of modern historians of astronomy, all 1022 stars listed in the catalog could be observed by Hipparchus at the latitude of Rhodes, 36° north latitude, but the catalog does not contain a single star that could be visible in the more southern Alexandria, 31°N latitude, but was not observed in Rhodes.

American physicist, specialist in celestial mechanics and history of astronomy Robert Newton, in his acclaimed book “The Crime of Claudius Ptolemy” (1977), directly accused the scientist of falsification and plagiarism. Calculations made by Russian astronomers, Yu.N. Efremov, and E.K. Pavlovskaya, who calculated the proper movements of all the stars of the Almagest, showed that they were observed mainly in the 2nd century BC. That is, Ptolemy actually used the Hipparchus catalogue, recalculating it for his era with a systematic error in precession (arising from the fact that he assumed precession to be 1 degree per 100 years, and not 72 years). As a result, the data on the positions of the stars turned out to be given for 60 AD, and not at all for 137 AD, as Ptolemy himself claims. However, modern scientists are not inclined to blame Ptolemy for this and, following Newton, accuse him of plagiarism, pointing out that he nowhere calls himself the author of the observations, his work is a reference book, and in reference books even in our time the authors of the material are not indicated.

Ptolemy also conducted his own observations of the stars; He observed them with the help of the “astrolabe” he invented - a combination of armillary spheres (later - the astrolabe). He also invented the “triquetrum” - a triple slat, which became the prototype of the wall circle (quadrant).

Ptolemy owns two geometric theorems that describe some properties of the diagonals of a quadrilateral inscribed in a circle,

and those who bear his name:

Ptolemy's first theorem.

Ptolemy's second theorem. A convex quadrilateral is inscribed if and only if the equality holds:

Based on these theorems, Ptolemy determined the arc chords of 1.5° and 0.75° and approximately calculated the arc chord of 1° from them. In doing so, he was based on the theorem he established, according to which the ratio of the larger chord to the smaller one is less than the ratio of the arcs subtended by them.

Ptolemy compiled a table of chords corresponding to arcs from 0° to 180° in increments of 0.5° (which is equivalent to a table of sines from 0° to 90° every quarter of a degree, that is, 15"). He also introduced the division of degrees into minutes and seconds.

American historian of mathematics Morris Kline:

The highest achievement of the Alexandrians was the creation by Hipparchus and Ptolemy of quantitative astronomy - a geocentric system of the world that allowed man to predict the movement of the planets, the Sun and the Moon. To build their quantitative theory, Hipparchus and Ptolemy developed trigonometry - a branch of mathematics that deals with the calculation of some elements of a triangle based on data about its other elements. Since Ptolemy's approach to constructing trigonometry differed from that accepted at that time, he had to calculate the lengths of the chords of a circle. Although Ptolemy used the deductive-geometric method to obtain basic results about the ratio of the lengths of some chords to the lengths of others, in the process of calculating the lengths of the chords (namely, they were ultimate goal calculations) he widely used arithmetic and the rudiments of algebra. The lengths of most chords were expressed in irrational numbers. Ptolemy was content with obtaining rational approximations of the quantities he needed, but in the course of calculations he did not hesitate to use irrational numbers.

In the treatise Optics (five books), Ptolemy experimentally studied the reflection and refraction of light at the interface of air - water and air - glass, after which he proposed his own law of refraction, which is approximately satisfied only for small angles. Ptolemy cites here the conclusions of Archimedes and Heron, but largely solves the question of the refraction of light in a new way. He pointed out the influence of refraction on astronomical observations, compiling tables to take it into account. For the first time he correctly explained the apparent increase in the Sun and Moon on the horizon as a psychological effect.

No less popular than the “Almagest” for a long time was Ptolemy’s astrological work “The Four Books” (Tetrabiblos), which systematized all the available data and theories about the influence of planets and stars on people’s lives and various events occurring on Earth. In this book, Ptolemy included the result of his statistical observations about the life expectancy of people: for example, a person aged 56 to 68 years was considered elderly, only after which old age began.

In the “Four Book” - in addition to the astrological material itself - Ptolemy for the first time expressed the deep philosophical idea of ​​\u200b\u200bthe incommensurability of celestial movements and, therefore, the impossibility of a complete repetition of events, as the Pythagoreans believed. These ideas of Ptolemy actually undermined the ideas of the cycle, providing food for a new rethinking of the surrounding Universe.

The “Four Books” were commented on by Porfiry and Proclus and translated many times, including into modern European languages.

In his main geographical work, “Guide to Geography” (Geographike hyphegesis), in 8 books, he considers this discipline as the science of depicting the Earth using drawings (this is how the title of the work can be translated closest to the original), which is based on astronomy and mathematics. We can say that Ptolemy laid the foundations of mathematical geography and cartography. To facilitate the compilation of maps, Ptolemy compiled tables of geographic latitudes and longitudes of approximately 8,100 of the most famous localities, mountains and rivers from Scandinavia to Egypt and from the Atlantic to Indochina. He described Britain and the countries south of the Baltic in more detail than his predecessors. Compiled 27 maps of the earth's surface. Despite the inaccuracy of this information and maps (compiled mainly from the stories of travelers), they were the first to show the vastness of the inhabited areas of the Earth and their connections with each other.

This work was highest achievement ancient geography, summing up its results. Ptolemy relied on the research of Eratosthenes, Hipparchus, Posidonius, Strabo, and above all on Marinus of Tire (Greek geographer of the 1st-2nd centuries AD).

For 14 centuries, Ptolemy's geographical treatise was not only a basic textbook on geography, but a source for the development of cartography in modern times.

In the treatise “Harmonika” (Harmonika), Ptolemy presented a complete theory of the pitch system (harmony) in contemporary music - from a detailed taxonomy of types of sound, intervals, types of consonance to a full-fledged (the only complete in ancient science) theory of mode. Porphyry wrote a most valuable commentary on the first chapters of Ptolemy’s Harmonics.

The contribution to science of Claudius Ptolemy cannot be overestimated. The scientist’s works in the fields of astronomy, physics, mathematics, geography and even music became, if not fundamental, then at least gave impetus to the development of these sciences. A lot of literature about the scientist’s achievements has survived to this day, but there is no biographical information.

Ptolemy developed a detailed reference book on ancient astronomy, which was published under the name “Almagest”. This work of the ancient scientist became the “bible of astronomy” down to the theory that laid the foundation for the science of celestial bodies.

The breadth of scientific interests and depth of analysis allowed Ptolemy to become the founder of scientific literature in the fields of geography, physics (optics), music theory, etc. Claudius also developed a theory according to which celestial bodies are constantly moving and function as one mechanism.

The doctrine of the stars and their influence on human destiny, called astrology, was also developed by Ptolemy. He also created an astronomical atlas, in which he indicated the constellations visible from the territory of Egypt.

Childhood and youth

Information about the biography of the ancient scientist has not been preserved. This is due to the fact that contemporaries avoided mentioning Ptolemy in their works. All available information is drawn from the books of the physicist Philip Ball, as well as from the ancient scientist’s own scientific works. It is known that Claudius lived on the territory of modern Egypt, in the city of Alexandria. Information about the scientist’s appearance has also not been preserved; the photos represent a kind of average image from the works of ancient sculptors.

In the book “Almagest” Ptolemy indicates the periods of astronomical observations, which help indirectly establish the dates of the scientist’s life: 127-151. However, after finishing work on the Almagest, at least two more books were published, which were encyclopedias, work on which lasted another 10 years. And according to the records of the philosopher Olympiodor, Claudius worked near Alexandria in the city of Kanope, a suburb of Alexandria Abukir.

Although the name of the scientist (Ptolemy) speaks of Egyptian origin, and biographical information indicates that he belonged to people from Greece, the first name (Claudius) indicates the Roman roots of its owner. Due to the lack of reliable information, it is not possible to establish the nationality of the scientist.

Science and discoveries

Ptolemy's scientific activity began with a work called “The Canopic Inscription,” which represents astronomical parameters carved on a stone stele in the city of Canopus (a suburb of Alexandria in Egypt). Later, the stele was destroyed, but the information written on it was preserved thanks to ancient Greek manuscripts.

Having clarified a number of information, Claudius developed “Tables at Hand” - something like an astronomical reference book. In the theory of geocentrism, this information acted as proof of the immobility of the Earth and the movement of other celestial bodies around it.

Before the world-famous Almagest, Ptolemy worked on a number of scientific books, including Planetary Hypotheses. The difference between this work and others lies in a different system of parameters used to describe the location of astronomical objects. In this treatise the term "ether" appears, which is tightly woven into Ptolemy's theory.

In the Almagest, Ptolemy calculated the distance from the Sun and Moon to the Earth with surprising accuracy for those times. The unit of measurement in the research was the radius of the Earth. However, in the same “Planetary Hypotheses”, the author indicated the distance between the Sun and other planets, without having their radius (instead, the scientist used the following conclusion: the radius of a planet is minimally equal to the distance from it to the next object in the visible Universe), which may indicate a discrepancy between the periods of writing scientific works.

The next book, according to researchers, was the work “Phases of Fixed Stars”. This work represents the first attempts to compile meteorological weather forecasts based on the position of celestial bodies and physical phenomena on the surface of the planet. In the same work, knowledge about climatic zones and geographical zones of the Earth, as well as the relative position of geographical objects.

To create astronomical theories, Ptolemy needed geometric knowledge about our planet. The theorem for calculating radii, arcs and circles is the subject of Claudius’s work entitled “Analemma”. The practical significance of this knowledge lies in the construction of sundials, which were built long before Ptolemaic research. The work “Planispheries” is devoted to stereographic projection and its application in astronomical calculations.

The Quadripartum became Claudius's most controversial work because it deals with the basics of astrology, or the influence of celestial bodies on human life. But the eight-volume “Geography” is not inferior to “Almagest” in popularity. It is not so much descriptive geography as mathematical geography with the basics of cartography. In the first volume, the scientist proposed to set the starting point from the prime meridian, which then served as the Canary Islands.

Disputes and discussions regarding Ptolemy's contribution to science are still ongoing, based on the fact that Hipparchus, long before Claudius, described the positions of the celestial bodies in the sky. The poet was the first to discover the falsification of data. And with the appearance of Copernicus on the international scientific arena, the astronomical teaching of Ptolemy became completely irrelevant. And only for some time he developed the theory of geocentrism, supporting the ancient scientist in his beliefs. However, the geocentric system of the universe was soon refuted by other scientists.

Personal life

No reliable information has been preserved about Claudius’s marital status, as well as the presence or absence of children. But it is known for sure that the scientist had followers and assistants who helped him make great discoveries in science. Ptolemy dedicated the astronomical book “Almagest” to Sir, but his identity has not been established, who he was as a scientist and whether he had anything to do with his research or astronomy is generally unknown.

The same treatise mentions the mathematician Theon, whose data Claudius used in astronomical calculations, but whether Theon was Ptolemy’s teacher or a colleague is also unknown.

A number of researchers suggest that we're talking about about Theon of Smyrna, a philosopher and follower who also studied the starry sky and compiled a primitive map of the night sky.

Claudius also had certain personal relationships with his employees scientific library in Alexandria of Egypt, since he had free access to the necessary literature. In historical sources of the beginning of our era, Claudius was associated with the Egyptian Ptolemaic dynasty, however modern researchers tend to consider this a coincidence.

Death of Ptolemy

The circumstances and date of the scientist’s death, like all the facts of his biography, remain a mystery to this day. The opinion of most researchers is that the date of death of Claudius should be considered 165 AD.

According to archival information, during this period a plague epidemic raged across the countries of Africa and Eurasia, of which Ptolemy may have become a victim. But even three thousand years after death, the scientist continues to live in his works and benefit his descendants.

Bibliography

• "Canopic Inscription"
• "Handy tables"
• "Planetary Hypotheses"
• "Phases of the Fixed Stars"
• "Analemma"
• "Planispherium"
• "The Four Books"
• "Geography"
• "Optics"
• "Harmonics"
• "On the ability to judge and make decisions"
• "Fetus"
• "Gravities" and "Elements"

Works in the field of astronomy are the main ones in the scientific work of Ptolemy. The main ones, but not the only ones. Ptolemy made great contributions to mathematical cartography, optics, and music theory (harmony).

Before Ptolemy, geography in the ancient world was purely descriptive, regional in nature. Extensive descriptions various countries and peoples, their way of life, customs, beliefs were left to us by the wonderful historian of ancient geographer Herodotus (c. 480 - 425 BC). But if the countries belonging to the Mediterranean and the shores of the Black Sea are described by him in sufficient detail and with very valuable information, then Herodotus reports many fabulous fables about India, Arabia and the countries located to the north of the Black Sea region.

Military campaigns (Xenophon in the 5th century BC, Alexander the Great in 332 - 322 BC) were used to study and describe those countries through which the conquerors’ path ran. Xenophon in his Anabasis gave a description of Asia Minor and Armenia. The commanders of Alexander the Great and the scientists who accompanied his army compiled a description of India. Alexander's army was accompanied by special “step counters”, which were supposed to measure the distances between settlements by counting steps. Based on the descriptions and calculations of the participants in the campaigns, a map of the known region of the Earth, Ecumene, was compiled by Dicaearchus from Messina (a student of Aristotle).

This direction in the geography of the ancient period is contained in the “Geography” of Strabo (65 BC - 2 AD) in seventeen books. Although Strabo made several long journeys during his long life, most of his descriptions are based not so much on his own observations as on generalizations of the descriptions of other authors. The first two books of his “Geography” are introductory in nature, in books III - X Europe is described, in books XI - XVI - Asia, in book XVII - Africa. Strabo described a lot of phenomena such as earthquakes, volcanic eruptions, the functioning of rivers, as well as the climate of various zones of the globe. Strabo knew that the Earth was spherical, based on the data of Eratosthenes, but he preferred to collect information about certain countries from travelers and sailors rather than use methods of mathematical cartography.

The foundations of the second direction in geography - mathematical cartography - were laid by Eratosthenes, who very accurately determined the size of the globe.

As is known, Eratosthenes' method was to determine the arc of the meridian between Alexandria and Syene on the day summer solstice. On this day, according to the stories of people who visited Siena, the Sun at noon illuminated the bottom of the deepest wells and, therefore, passed through the zenith. Consequently, the latitude of Syene was equal to the angle of the ecliptic to the equator, which Eratosthenes determined at 23? 51` 20". On the same day and hour in Alexandria, the shadow from the vertical column of the gnomon covered 1150 part of the circle, the center of which was the tip of the gnomon. This means that the Sun was 1/50th of a circle away from the zenith at noon. Taking the distance between Alexandria and Syene as 5000 stadia, Eratosthenes found that the circumference of the globe was 250,000 stadia. The question of the exact length of the stage adopted by Eratosthenes has long been a subject of debate, since there were stages from 148 to 210 m in length. Most researchers accepted the length of the stage as 157.5 m (“Egyptian” stages). Then the circumference of the Earth is, according to Eratosthenes, 39,375 km, which is very close to the actual value of 40,008 km. If Eratosthenes used the Greek (“Olympic”) stage with a length of 185.2 m, then the circumference of the Earth was already 46,300 km.

Eratosthenes wrote a lot of work entitled “Geography” in three books, unfortunately not preserved. However, we know about its content from Strabo’s rather detailed account. In the first book Eratosthenes gives geographical descriptions their predecessors since ancient times. He talks about the first geographical maps, built by Anaximander and Hecataeus. The second book sets out the evidence for the sphericity of the Earth and the method described above for measuring its size. Eratosthenes (like many others) considered the Ecumene to be an island surrounded on all sides by the ocean. He first expressed the opinion that India could be reached by sea, sailing west. In the third book, Eratosthenes gave detailed comments on the map of the Ecumene he compiled.

Hipparchus sharply criticized Eratosthenes’ “Geography,” devoting a separate book to this issue, which also has not reached us. We know about it, as well as about the work of Eratosthenes, from Strabo’s “Geography”. Hipparchus considered it unacceptable to use the evidence of travelers and sailors about a particular distance of geographical points from each other to construct maps of the earth's surface.

To construct maps, Hipparchus accepted only precise definitions of latitudes and longitudes. In those days it was not so easy. Latitudes could be measured, as Pytheas did, by the height of the stars in the meridian or by the height of the Sun at noon. This could be done on any clear day or night. The situation was worse with longitudes. At that time, there was only one way to determine the difference in longitude of two points: simultaneous observations lunar eclipses, which occur infrequently, and cloudy weather can interfere.

Hipparchus introduced the grid of meridians and parallels as a mathematical basis for drawing maps of the earth's surface. Along with Eratosthenes, he can rightfully be considered one of the founders of mathematical cartography.

A certain contribution to measuring the size of the Earth was made by Posidonius (c. 135 - 50 BC), who, like Hipparchus, worked in Rhodes and later in Rome. He was a Stoic philosopher, but also did a lot of mathematics.

Such were the works of Ptolemy's predecessors. However, in his “Geography” he refers to another of his predecessors - the geographer Marinus of Tyre (that is, originally from the city of Tire), who, like Ptolemy, developed methods of mathematical cartography. Unfortunately, we do not know exactly the time of life of Marin of Tire (approximately 1st century AD). It was Marin who proposed to count longitudes from one of the Canary Islands, so that all longitudes of the Ecumene would have the same sign. Ptolemy borrowed this method of counting longitudes from him. To construct maps, Ptolemy used the rectangular projection proposed by Marinus.

Ptolemy's "Geography" is a huge volume (not much inferior to the "Almagest"). This book gives longitudes and latitudes of approximately 8000 settlements. The book is illustrated with 27 maps: one general and 26 by region (Ptolemy calls them the Greek word “diocese”; in Latin translations “provinces” appear). A general map of the world is attributed to the Alexandrian geographer Agathodemon.

Unfortunately, the original maps of Ptolemy have not reached us, so we can judge them only from copies and reconstructions.

Ptolemy's Geography, also called the Geographical Manual, consists of eight books. In Book I, Ptolemy sets out his ideas about globe and gives an idea of ​​​​geographic coordinates: latitude and longitude.

His views on geographical science are based on a mathematical approach to drawing maps and determining the positions of cities and other points. Ptolemy sharply criticizes the regional approach, based only on the use of qualitative descriptions of travelers, without a mathematical basis.

Books II - VII are devoted to the description of individual regions. According to Ptolemy’s ideas, the Oecumene is located in the range of longitudes (in the system he adopted) from 0? up to 180? and in the latitude range from 20? Yu. w. up to 63? 30`s. w. The prime meridian is taken to be the meridian passing at 0.5? west of the Isles of the Blessed, i.e. the Canary Islands.

A comparison of the coordinates of cities that existed in the Ptolemaic era and still exist shows that Ptolemy’s grid of longitudes seems to stretch to the east. Therefore, the longitudes of London (Londinium) and Paris (Lutetia) differ from modern ones by 20? and 21?.

Let's move on to presenting the contents of books II - VII of Ptolemy's Geography. The sixteen chapters of Book I describe the countries of Western Europe. Among them are Hibernia (Ireland), Albion (Great Britain), Spain (this includes modern Spain and Portugal), Gallia Aquitaine (France), Gallia Belgica (northeastern France, Belgium and the Netherlands), Greater Germany (Germany and part of Poland up to the Vistula ), Rezia, Vindelizia and Norik (Bavaria and Austria), Pannonia (Hungary). Book III deals mainly with countries of Eastern Europe. Among them are Illyria (the Adriatic coast of Croatia), Dalmatia (the coast of Bosnia and Albania), Italy, the islands of Corsica, Sardinia and Sicily, European Sarmatia (Eastern Europe from the Vistula to the Don), Taurian Chersonesos (Crimea), Dacia (Romania), Upper and Lower Moesia (Serbia and Bulgaria), Thrace (southern Bulgaria and European Turkey), Macedonia, Epirus, Achaea (Greece), Peloponnese, Euboea and Crete. Ptolemy classifies Asian Sarmatia, that is, Eastern Europe from the Don to the Volga, as Asia and describes it in Book V. He considers the eastern border of Europe to be the river. Tanais (Don).

Ptolemy incorrectly imagined the northern countries and seas of the European continent. He considered the Scandinavian peninsula to be a small island of Scandia. He considered the Baltic Sea to be part North Sea, uniting these seas into the Sarmatian Ocean. The British Isles on his maps are greatly distorted, especially in their northern part.

It is interesting that Ptolemy already has the names of some Slavic tribes. Thus, he mentions the Wends and even calls a part of the Baltic Sea by their name the Gulf of Veneds. He names the Serbs, and the Stavans and Svovens he mentions are Slavs and Slovenes, the Bulans are Polans. Thus, already in the Ptolemaic era, Slavic peoples existed and inhabited part of Eastern Europe.

Among the mountains, Ptolemy mentions the Alps, Sudetes, Carpathians and Sarmatian mountains. It is difficult to say what Ptolemy meant by the Sarmatian mountains. neither, according to Ptolemy, are located north of the Carpathians. It is possible that he assumed the existence of some northern spurs of the Carpathians.

Ptolemy calls the Sea of ​​Azov Meotida, after the name of the Meotian (Adyghe) tribe. He mentions several rivers flowing into it. In addition to the Tanais (Don), the Vardan, or Gipanis (present-day Kuban), Porit (now Mius), Lik (Kalmius), Marubiy (Kagalnik), and a total of 13 rivers are listed, of which seven rivers flow from the east, and six from the west .

Ptolemy calls the Volga Ra. This name existed among the ancient peoples of the Volga region; After all, the Volga is still called Rav in the Mordovian language.

In Book IV of his Geography, Ptolemy describes Africa. He divides it into the following 12 “dioceses”: Mauritania Tingitana, Mauritania Caesarea, Numidia, Africa proper, Cyrenaica, Marmarica, Libya external, Lower Egypt, Middle Egypt, Thebaid, Libya internal, Ethiopia, Upper Egypt, areas south of Ethiopia. The extreme southern point that he mentions is Mount Bardit (16? S), although Ptolemy considers parallel 20? Yu. w.

The part of Africa included in the Ecumene is depicted by Ptolemy on four maps. Its outlines are distorted compared to modern ones, primarily due to stretching in the longitudinal direction. Thus, the Mediterranean coast of Africa from Tingin (now Tangier) to Cassium (Port Said) covers more than 57? in longitude instead of 38? in fact. South of the equator, Ptolemy's Africa expands to the east and west. In addition, there are a number of other deviations in the shape of the coast (both Atlantic and Mediterranean) from the correct one.

Describing (and in some detail) the Nile River and the cities of the Nile basin, Ptolemy shifts its source to the south by 9?30` towards the Lunar Mountains. Ptolemy calls the country in East Africa, located on the site of present-day Somalia and Kenya, Barbaria. The southernmost city in East Africa mentioned by Ptolemy is Rapta at 7? Yu. w. (now Dar es Salaam in Tanzania), an ancient port and shopping mall Africa.

In Ptolemy's "Geography" in Africa, 40 mountains are indicated, including the Lunar Mountains, the Libyan Mountains, the Great and Small Atlas, the Solar Mountain, etc. Of the rivers, the Nile and the river are indicated. Daradus (now Senegal), Nigueir (Niger) and many others.

In the same IV book, Ptolemy describes the islands of the Red Sea (29 islands are listed), as well as the islands Mediterranean Sea adjacent to the African continent.

More than half of Geography (Books V - VII) is devoted to a description of Asia. Moreover, if the countries of Western Asia, the Near and Middle East are described quite correctly, then as we move to more eastern countries Ptolemy's information becomes less and less accurate.

These are the “dioceses” Ptolemy attributes to Asia: Pontus, Bithynia, Asia proper, Lycia, Galatia, Paphlagonia and Pisidia, Pamphylia and Isauria, Cappadocia, Armenia Minor, Cilicia, Asian Sarmatia, Colchis, Iberia, Albania, Armenia Great, island of Cyprus, Syria valley, Syria Phenicia, Syria Palestine and Judea, Arabia Stony, Mesopotamia, Arabia Desert, Babylonia, Assyria, Media, Susiana, Persis, Parthia, Carmania Desert, Arabia Happy, another Carmania, Hyrcania, Marciana, Bactriana, Sogdiana, country Sakov, Snifiya, Serika, Aria, Paropamis, Drangiana, Arachosia, Gedrosia, India, country of the Sins, Taprobana Island.

Most of these names require some explanation. Pontus and Bithynia are parts of the Black Sea coast of what is now Turkey, adjacent to the Bosporus. Galatia is located further south. Cappadocia is located to the east, also on the territory of modern Turkey. The southern part of Turkey along the Mediterranean coast was then called Cilicia. Ptolemy calls the remaining parts of modern Turkey “Asia proper.” Colchis and Iveria are the Black Sea coast and mountainous regions of Georgia, respectively, Albania is now Azerbaijan.

During the Ptolemaic era, Armenia occupied not only the current territory of the Armenian SSR, but also a significant part of Eastern Turkey. Its western part was called Lesser Armenia. Hyrcania was adjacent to the southern shore of the Caspian Sea (part of modern Iran), Media was located to the southwest of it, Susiana extended further to the south, and Persida was located off the coast of the Persian Gulf. All these “dioceses” were also located on the territory of modern Iran. East of Media was Parthia (Eastern Iran), and east of Persis was Carmania. Even further east of Karmania, along the northern shore of the Arabian Sea, was Gedrosia, covering the southeastern part of Iran and the western part of Pakistan. Arachosia was located north of it, in the territory of modern Afghanistan. Even further north was Bactriana (northern Afghanistan), and then Sogdiana (in what is now Uzbekistan). To the northeast of it extended the country of the Sakas (southern Kazakhstan, along the banks of the Syr Darya). Scythia meant part of the Russian territory from the Volga to Lake Balkhash, Marciana meant part of Turkmenistan. The Northern Caucasus was then called Asian Sarmatia. Taprobana is an island in Sri Lanka.

Ptolemy believed Indian Ocean a closed sea, bounded from the west and south by the shores of Africa, from the north - Happy Arabia, Persia, Gedrosia and India, from the east - the country of the Sins. Ptolemy called the south of the Malay Peninsula the Golden Chersonese. Serika is China (“the country of silk”), and the country of the Sins is Indochina. Despite numerous errors in the depiction of certain geographical regions, Ptolemy’s work retained its significance almost until the 17th century. Although in the works of Arab and Central Asian scientists (especially Muhammad al-Khwarizmi and Abu-Rayhan Biruni) many of Ptolemy’s errors were corrected and the coordinates of a number of Asian cities were determined anew, Ptolemy’s “Geography” continued to be used, and in the 12th century, like the “Almagest” , came to Europe.

PTOLEMY(Ptolemaios), Claudius

about 90 - about 168

The Greek geometer, astronomer and physicist Claudius Ptolemy spent most of his life in Alexandria, where in 127–151. made astronomical observations; no information about his biography or even his place of birth has been preserved. Ptolemy developed the so-called geocentric system of the world, according to which all visible movements of the celestial bodies were explained by their movement (often very complex) around the stationary Earth. Ptolemy's main work on astronomy is “The Great Mathematical Construction of Astronomy in 13 Books,” known by the Arabized name “Almagest.”

This work, consisting of 13 books, contains all the main things he did in the field of mathematics, namely trigonometry. Both are contained, respectively, in the 9th and 11th chapters of the first book of the work, which is generally devoted to the presentation of preliminary astronomical concepts and information, including: an indication of the circles and coordinates used on the celestial sphere; the teaching that all stars have spherical motion, that the Earth is a motionless ball located at the center of the universe; that the Sun, Moon and planets, except general movement, also have their own, directed opposite to the first, etc. The second book of the Almagest deals with the division of the Earth into zones, the lengths of the day and the midday shadow lengths along various parallels, as well as the phenomena of sunrise and sunset. The third book examines the length of the year down to the minute, and then sets forth Hipparchus' theory of the Sun. The fourth book is devoted to determining the length of the month and expounding the theory of the movement of the Moon. The fifth deals with a description of the structure of the astrolabe and casually indicates new measurements made with its help, which the author used in order to more accurately study the inequalities in the movement of the Moon. The sixth book studies conjunctions and oppositions of the Sun and Moon, together with the conditions for the origin of eclipses; the possibility of approximate calculation of their occurrence is indicated. The seventh book contains an article on the anticipation of the equinoxes and the oldest star catalog that has come down to us, dating back, in all likelihood, to Hipparchus. It describes in order all the 48 constellations known to the Greeks (21 to the north of the zodiac, 12 constellations of the zodiac and 15 to the south of it), embracing a total of 1022 stars, given partly by their position in the constellation figure, partly by longitude, latitude and visible magnitude, not passing beyond the sixth. Book eight is devoted to a detailed description of the appearance Milky Way, which is called the galactic circle in it. However, it does not explain the phenomenon it represents. The last 5 books deal with the planets or the “Ptolemaic system” itself, the intricacy and complexity of which stems from the accumulation of epicycles, deferents, and equants caused by the position of the immobility of the Earth. In the Middle Ages, objections to the Ptolemaic system were viewed as heresy and a crime, which could even cost a monarch his crown (Alfonso X, King of Castile).

Before the appearance of the book “On Appeals” celestial spheres"Nicholas Copernicus's Almagest remained an unsurpassed example of presentation of the entire body of astronomical knowledge. It was exceptionally great practical significance this work for navigation and determining geographical coordinates. In the Almagest, for the first time, the laws of the visible movements of celestial bodies were established so much that it became possible to pre-calculate their positions. At the beginning of the 17th century, during the struggle to establish the heliocentric system of the world, the attitude towards Ptolemy’s work changed sharply, since it began to be seen primarily as a support for geocentric views; at the same time, after the appearance of the tables of Copernicus and especially Johannes Kepler, this work lost its practical significance.

Other works of Ptolemy, “Guide to Geography” (8 books), were also very famous (from 1475 to 1600, 42 editions of this work were published). It provides a complete, well-systematized summary geographical knowledge ancient. Ptolemy especially did a lot to develop and use the theory of map projections. He gave coordinates of 8000 points (in latitude - from Scandinavia to the headwaters of the Nile, and in longitude - from the Atlantic Ocean to Indochina), based, however, almost exclusively on information about the routes of merchants and travelers, and not on astronomical definitions. The treatise is accompanied by one general and 26 special maps of the earth's surface.

Astronomical observations dated back in ancient times to the reign of kings. In this regard, Ptolemy compiled the "Chronological Canon of the Kings", which is an important source for chronology. The five-volume treatise on optics he wrote was considered completely lost. But in 1801, an almost complete Latin translation was found, made from Arabic. Of greatest interest in it are the theory of mirrors developed by Ptolemy, tables of angles of refraction when a light ray passes from air to water and glass, as well as the theory and table of astronomical refraction (and Ptolemy assumes that the atmosphere extends to the Moon). In an article on the theory of vision, Ptolemy considers rays of light flowing towards a visible object from the eye. Ptolemy's other writings are of less interest; It is known about the existence of a number of works by Ptolemy (in particular, on mechanics), which have not reached our time.

Claudius Ptolemy - scientist, astrologer, geographer and philosopher. His name is associated with the creation of a geocentric system of the world. However about early years Almost nothing is known about his life. There is also no exact date of birth and death. His contemporaries never mentioned the name of Claudius Ptolemy in their writings. This was due to the fact that in ancient times everyone was guided by a religious worldview, and having your own scientifically based opinion was practically prohibited. Since the works of Ptolemy could shake the established opinion about the formation of the world, practically nothing was said about him.

Historians are of the opinion that Ptolemy came from a family of crowned heads. However, this point of view was not confirmed. From the works of the physicist Philip Ball it is known that Claudius lived for a long time in Alexandria in Egypt. The year of birth of Ptolemy is considered to be approximately 68-70. Exact date birth unknown. There is also no information about the scientist’s education or family. However, his name - Claudius - indicates the scientist's Roman origin, and small biographical data indicates his connection with Greece. Therefore, it is not possible to establish exact information about his nationality.

The main value is represented by the scientist’s works, which for a long time were considered the main materials on geography, physics and the system of the universe. True, at present these works cannot be compared with the modern scientific picture of the world. Due to the fact that nothing was known about Claudius for a long time, no records of his appearance and family relationships.

The book of the philosopher Olympiador mentions the life of Claudius in the Alexandrian city of Canopus. And also according to information from the Almagest, Ptolemy conducted his astronomical research around the years 127-151. This helps to establish the approximate years of a scientist's life. It should be noted that after “Almagest” two more books were published, work on which took the scientist another 10 years.

Work and writings of Claudius Ptolemy

Due to the specific features of that time, only a few works of the great scientist have reached us. The geocentric picture of the world created by Ptolemy caused many negative responses from the authorities and religion, so his works were not published for a long time. The scientist's contemporary mentioned his name in their works, so there is little information about Ptolemy's work.

His most important works are considered to be “Geography” and “Almagest”, For a long time these books were teaching aid for many future scientists. Their reliability has not been questioned for several centuries. In the book "Geography" Claudius gave coordinates of various places, territories and states. The work also contained the first geographical maps.

Claudius worked in Egypt for about 40 years. Ptolemy was the author of many scientific books and treatises, which played a significant role in the development of Islamic and European science.

Claudius Ptolemy conducted many scientific observations and experiments. He ordered his first notes to be carved on stones in Canopy. This information, called the “Canopic Inscription,” has survived to this day. Of particular importance was the work "Almagest", in which Claudius reliably substantiated the existence of a geocentric picture of the world, compiled a catalog of the starry sky, and also recorded astronomical knowledge from Ancient Greece and Babylon. These data remained immutable until the presentation of the ideas of Nicolaus Copernicus. However, it was the Almagest that made Ptolemy a famous scientist.

Contributions of Claudius Ptolemy to other sciences

The name of Claudius Ptolemy is associated not only with the development of astronomy and geography, but also with work in the field of optics, physics, and music theory. The five books of “Optics” outline the theory of the nature of vision and the refraction of rays. The book contains information about mirrors, the properties of light and visual illusions.

The scientist's work "Phases of Fixed Stars" was the first attempt to create a weather forecast by studying the movement of celestial bodies and physical phenomena on the planet. The same book presented the results of studying climatic zones and geographical zones planets. Ptolemy became famous as a scientist - demographer, writing a treatise "The Four Books", based on Claudius' study of human life expectancy, as well as various ages.

In his work on the theory of the movement of celestial bodies and their influence on human life, Ptolemy relies on the works of only one scientist - Aristotle. It was his works that he considered truly true, so he used them as evidence of his observations. Claudius assumed that human development is influenced by the date of his birth, the location of the stars and planets at that moment. The scientist sincerely believed that astrological findings could be used in life.

Claudius Ptolemy is the author of many different reference books. The most famous are his reference books on geography, in which he was able to summarize the knowledge of many scientists and his observations. He created the first geographical atlas, which included maps of Europe, Asia and continents.

However, Ptolemy's works cannot currently be considered reliable. He was wrong about the size of the continents, the location of cities and territory. This was due to incorrect data obtained by other scientists, as well as the picture of the world that existed at that time.

His works are valuable because they bring together the works of many ancient Greek and Roman scientists. Claudius Ptolemy did not put his authorship on the treatises.