Who is Eratosthenes? It is believed that this person calculated the exact dimensions of the Earth, but this ancient Greek scientist and the head of the famous Alexandria Library had other achievements. His range of interests is striking: from philology and poetry to astronomy and mathematics.
The contribution of Eratosthenes to geography is still amazing. 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 an outstanding scientist in order to answer the question of who Eratosthenes is.
Brief general information about the person
History has kept brief information from the biography of Eratosthenes, however, it was often referred to by authoritative and famous sages, philosophers of antiquity: Archimedes, Strabo and others. 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. It was not in vain that his contemporaries gave him the nickname Pentacle, or multi-wrestler. The living mind of Eratosthenes tried to comprehend almost all the sciences known at that time. And like all scientists, he watched nature. Another nickname describing the works and discoveries of Eratosthenes has survived. He was also called the "beta", or "second." No, by this they in no way wanted to humiliate him. This nickname spoke of his erudition and quite high achievements in the study of sciences.
What does it mean to be an ancient Greek?
The ancient Greeks were skilled travelers, warriors, and merchants. New countries and lands attracted 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 particular policy, was rather 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, so passionately loved to travel. The craving for a new one led him to Athens, where he continued his studies.
Life in Athens
In Athens, he did not waste time and continued his studies. At one time, poetry helped him to comprehend the great Callimachus grammar - Lisany. In addition, he became acquainted with the philosophical teachings and schools of the Stoics and Platonists. He called himself a follower of the latter. Absorbing knowledge in two famous centers of science and culture of Ancient Greece, he was best suited for 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 Alexandria Library, and later he became its head.
Alexandria Library
The library was not just an academy or a meeting place for ancient knowledge. She was the focus of science of the time. Asking the question of who Eratosthenes is, one cannot fail to mention the activity that he launched as he was appointed chief curator of the Library of Alexandria.
Many famous philosophers of antiquity lived and worked here, as well as trained personnel for the Ptolemaic administration. A huge staff of census takers and the presence of papyrus allowed replenishing funds on the spot. The Alexandria library competed worthy with Pergamum. Some more steps were taken to increase the fund. All scrolls and parchments found on ships were carefully copied.
Another innovation of Eratosthenes is the establishment of an entire department studying Homer and his legacy. He spent a lot of his personal funds on the purchase of ancient scrolls. According to some information that has been preserved to this day, over seven hundred thousand manuscripts and parchments were stored here. Eratosthenes continued the work of his teacher Kallimachus, who founded a scientific bibliography. And until 194 BC e. faithfully fulfilled his obligations until a misfortune happened to him - he became blind and could not do what he loved. This circumstance deprived him of a craving for life, and he died, ceasing to eat.
Godfather of geography
The book of Eratosthenes “Geography” is not just a scientific work. It was an attempt to systematize the knowledge obtained at that time about the study of the Earth. So a new science was born - geography. Eratosthenes is also considered the creator of the first world map. In it, he divided the earth's surface conditionally into 4 zones. He allocated one of these zones for people to live, placing it strictly in the north. According to his ideas and on the basis of the then known data, man could not physically exist to the south. Too hot climate would make this impossible.
Separately, it is worth mentioning the invention of the coordinate system. This was done to simplify the search for any item on the map. Such concepts as parallels and meridians were also introduced for the first time. The geography of Eratosthenes is supplemented by another idea that modern science adheres to. He, like Aristotle, considered the World Ocean to be single 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 reached our days. Only a few fragments and individual references have been preserved. The “Geography” of Eratosthenes was no exception.
"Catastrophes" - turning into a constellation
The ancient Greeks, like many other peoples, paid close attention to the starry sky, as evidenced by some surviving works. A biography of Eratosthenes mentions his interest in astronomy. "Catastrophes" is a treatise in which the ancient Greek mythology and observations of more than 700 celestial objects were combined. The issue of authorship of Eratosthenes still causes a lot of controversy. One of the reasons is stylistic. It is extremely difficult to believe that Eratosthenes, who paid so much attention to poetry, wrote "Catastrophes" with a dry, devoid of any emotional syllable. In addition, this historical source sins with astronomical errors. However, official science attributes authorship precisely to Eratosthenes.
Earth Size Measurement
Observing Egyptians noticed one interesting fact, which then formed the basis of the principle of measuring the Earth by Eratosthenes. On solstice days in different parts of Egypt, the sun illuminates the bottom of deep wells (Siena), but in Alexandria this phenomenon is not observed.
What tool did Eratosthenes use to calculate the size of the earth? June 19, 240 BC e. in Alexandria on the day of the summer solstice, with the help of 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. It amounted to various sources from 250,000 to 252,000 stages. Translated into a modern system of estimates, 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 a calculation accuracy was simply phenomenal.
Mesolabia
Unfortunately, the work of Eratosthenes in the field of mathematics has practically not survived to this day. All information has come to the present in the comments of Eutocius about the letters of Eratosthenes to King Ptolemy. They provide information on the Delhi problem (or “doubling the cube”), describe the mechanical device of mesolabium, which is used to extract cubic 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 the point K is in the middle of the side of DB, and two free triangles are located so that the intersection points of their sides (L and N) coincide with the straight line AK, the volume of the cube with the edge ML will be twice as large as the cube with the edge DK.
Sieve of Eratosthenes
This technique, used by scientists, is described in the treatise of Nikomakh Gerazensky and serves to determine prime numbers. It was noted that some numbers can be divided into 2, 3, 4 and 6, while others are divided without a remainder only into themselves. The latter (for example, 7, 11, 13) are called simple. If you need to determine 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 other methods for determining prime numbers have not been invented.
Natural numbers are divided into three groups:
- having 1 divider (unit);
- having 2 divisors (prime numbers);
- having divisors greater than two (compound numbers).
The essence of the method is to sequentially cross out all the numbers except simple ones. First, numbers that are multiples of 2 are deleted, then 3, and so on. The end result should be a table with pristine numbers (prime). Eratosthenes built a sequence of primes up to 1000. The table shows the first five hundred numbers.
Instead of a conclusion
Given the safety of the manuscripts of the Greek thinker, a more complete picture of who Eratosthenes is could be made. However, history has not provided modern people with such an opportunity. Therefore, descriptions of his inventions are collected from treatises and references of 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 today. And the ancient Greek contemporary of the thinker Archimedes, paying tribute to his colleague, dedicated his creation "Ephodicus" (or "Method") to him. Eratosthenes possessed encyclopedic knowledge in many sciences, but he liked it when he was 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.