Who is Eratosthenes? It is believed that this man calculated the fairly accurate dimensions of the Earth, but this ancient Greek scientist and the head of the famous Library of Alexandria had other achievements. The range of his interests is amazing: from philology and poetry to astronomy and mathematics.
The contribution of Eratosthenes to geography is amazing to this day. This is largely due to the eccentricity of the personality of the ancient Greek scientist. It is necessary to reveal the least known facts in the biography of this mysterious man and outstanding scientist in order to answer the question of who Eratosthenes is.
Brief Personal Profile
History has preserved brief information from the biography of Eratosthenes, but authoritative and famous sages, philosophers of antiquity: Archimedes, Strabo and others, very often referred to him. The date of his birth is considered to be 276 BC. e. Eratosthenes was born in Africa, in Cyrene, so it is not surprising that he began his education in the capital of Ptolemaic Egypt - Alexandria. Contemporaries knowingly gave him the nickname Pentacle, or all-around. The lively mind of Eratosthenes tried to comprehend almost all the sciences known at that time. And like all scientists, he observed nature. There is another nickname that describesworks and discoveries of Eratosthenes. It was also called "beta", or "second". No, they did not mean to humiliate him in any way. This nickname spoke of his erudition and rather high achievements in the study of science.
What does it mean to be an ancient Greek?
The ancient Greeks were skilled travelers, warriors and merchants. New countries and lands beckoned them, promising benefits and knowledge. Ancient Greece, divided into many policies, and the existing pantheon of gods, where each of them was the patron of a certain policy, was more of a geopolitical space. The Greeks were not a nationality, it was a cultural Hellenistic community of people who considered all other peoples to be barbaric, who needed help by introducing them to culture and civilization.
Therefore, Eratosthenes, like most ancient Greek philosophers, loved to travel so enthusiastically. The craving for the new and led him to Athens, where he continued his studies.
Life in Athens
In Athens, he did not waste time and continued his studies. Poetry to him at one time, helped to comprehend the great Callimachus grammar - Lysanias. In addition, he got acquainted with the philosophical teachings and schools of the Stoics and Platonists. He called himself an adherent of the latter. Absorbing knowledge in two of the most famous centers of science and culture of ancient Greece, he was best suited to the role of mentor for the heir. Ptolemy III, not stinting on promises and promises, persuaded the scientist to return to Alexandria. And Eratosthenes could not resist the opportunity to work in the Library of Alexandria,and later he became its head.
Alexandrian Library
The library was not just an academy or a place of collection of ancient knowledge. It was the center of science of that time. Asking the question of who Eratosthenes is, it is impossible not to mention the activities that he launched when he was appointed chief curator of the Library of Alexandria.
Many famous philosophers of antiquity lived and worked here, and personnel for the Ptolemaic administration were trained here. A huge staff of scribes and the presence of papyrus made it possible to replenish funds on the spot. The Library of Alexandria competed worthily with that of Pergamon. Some more steps were taken to increase the fund. All the scrolls and parchments found on the ships were carefully copied.
Another innovation of Eratosthenes is the establishment of a whole department that studies Homer and his heritage. He also spent a lot of his personal money on the purchase of ancient scrolls. According to some information that has survived to this day, over seven hundred thousand manuscripts and parchments were kept here. Eratosthenes continued the work of his teacher Callimachus, who founded the scientific bibliography. And until 194 BC. e. faithfully fulfilled the obligations assigned to him, until a misfortune happened to him - he became blind and could not do what he loved. This circumstance deprived him of the will to live, and he died without eating.
The Godfather of Geography
The book of Eratosthenes "Geography" is not just a scientific work. It attempted to systematizethe knowledge gained at that time about the study of the Earth. Thus was born a new science - geography. Eratosthenes is also considered the creator of the first map of the world. In it, he conditionally divided the earth's surface into 4 zones. He singled out one of these zones for human habitation, placing it strictly in the north. According to his ideas and on the basis of the then known data, a person purely physically could not exist further south. Too hot climate would make it impossible.
We should also mention the invention of the coordinate system. This was done to make it easier to find any point on the map. Also, concepts such as parallels and meridians were introduced for the first time. The geography of Eratosthenes is supplemented by another idea, which modern science also adheres to. He, like Aristotle, considered the oceans to be one and undivided.
Official history claims that the great Library of Alexandria was barbarously destroyed by Roman legionnaires. For this reason, many ancient priceless works have not survived to this day. Only a few fragments and individual references have survived. The "Geography" of Eratosthenes was no exception.
"Catasterisms" - transformation into a constellation
The ancient Greeks, like many other peoples, paid close attention to the starry sky, as evidenced by some works that have come down to us. A biography of Eratosthenes mentions his interest in astronomy. Catasterisms is a treatise that combines the ancient mythology of the Greeks and observations of more than 700 celestial objects. The question of the authorship of Eratosthenes is stillhas been causing a lot of controversy. One reason is stylistic. It is extremely difficult to believe that Eratosthenes, who paid so much attention to poetry, wrote the Catasterisms in a dry, devoid of any emotional style. In addition, this historical source is also guilty of astronomical errors. However, official science attributes authorship to Eratosthenes.
Measuring the size of the Earth
The observant Egyptians noticed one interesting fact, which later formed the basis of the principle of measuring the Earth by Eratosthenes. On the days of the solstice in different parts of Egypt, the sun illuminates the bottom of deep wells (Siena), but in Alexandria this phenomenon is not observed.
Which tool did Eratosthenes use to calculate the size of the Earth? June 19, 240 B. C. e. in Alexandria on the day of the summer solstice, using a bowl with a needle, he determined the angle of the sun in the sky. Based on the result, the scientist calculated the radius and circumference of the Earth. According to various sources, it ranged from 250,000 to 252,000 stages. Translated into the modern system of calculations, it turns out that the average radius of the Earth was 6287 kilometers. Modern science calculates such a radius and gives a value of 6371 km. It is worth noting that for that time such calculation accuracy was simply phenomenal.
Mesolabia
Unfortunately, the works of Eratosthenes in the field of mathematics have practically not survived to this day. All the information has come down to the present in the comments of Eutocius on the letters of Eratosthenes to King Ptolemy. They provide information aboutDelhi problem (or "doubling the cube"), a description is given of the mechanical device of the mesolabium, which serves to extract cube roots.
The device consisted of three equal right triangles and two rails. One of the figures is fixed, and the other two can move along the rails (AB and CD). Provided that point K is in the middle of side DB, and two free triangles are located in such a way that the points of intersection of their sides (L and N) coincide with line AK, the volume of a cube with edge ML will be twice as large as a cube with edge DK.
Sieve of Eratosthenes
This technique, used by the scientist, is described in the treatise of Nicomachus of Gerazene and serves to determine prime numbers. It was noticed that some numbers can be divided by 2, 3, 4 and 6, while others are divisible without a remainder only by themselves. The latter (for example, 7, 11, 13) are called simple. If you need to define small numbers, then, as a rule, there are no problems. In the case of large ones, they are guided by the rule of Eratosthenes. In many sources, it is still called the sieve of Eratosthenes, and no other methods for determining prime numbers have been invented.
Natural numbers are divided into three groups:
- having 1 divisor (one);
- having 2 divisors (prime numbers);
- having divisors greater than two (composite numbers).
The essence of the method lies in the successive deletion of all numbers, except for prime ones. Numbers that are multiples of 2 are removed first, then 3, and so on. In the endthe result should be a table with untouched numbers (prime). Eratosthenes built a sequence of prime numbers up to 1000. The table shows the first five hundred numbers.
Instead of a conclusion
If the manuscripts of the Greek thinker were preserved, it would be possible to get a more complete picture of who Eratosthenes was. However, history has not provided modern people with such an opportunity. Therefore, descriptions of his inventions are collected from treatises and references by other authors.
No less mysterious is the life of Eratosthenes. Unfortunately, historical sources conveyed scant information about the bright personality of the thinker and philosopher. However, the scale of the genius of Eratosthenes is amazing even today. And the ancient Greek contemporary of the thinker Archimedes, paying tribute to his colleague, dedicated his creation “Ephodik” (or “Method”) to him. Eratosthenes had an encyclopedic knowledge of many sciences, but he liked being called a philologist. Perhaps the lack of communication with the texts during his illness led him to starvation. But this fact does not detract from the merits of the genius of Eratosthenes.
