Born around 276 B.C. in Cyrene , Libya , Eratosthenes soon became one of the most famous mathematicians of his time . He is considerably screw for making the first record measuring of the Earth ’s circumference , which was also remarkably accurate . ( And , yes , people at that point had known for some fourth dimension that the world was n’t flat , contrary to popular belief . )
Eratosthenes was able to accomplish this in part because of his training in Athens . There , he became known for his achievements in many dissimilar subject , including poetry , uranology , and scientific authorship . His activities became so talked about , in fact , that Ptolemy III of Egypt decided to invite him to Alexandria to tutor his Word . by and by , he would become the promontory librarian of the Library of Alexandria .
The mathematician must have been thrilled to have this chance . The Library of Alexandria was a hub of learning at the time , attracting assimilator from across the known world . Eratosthenes was capable to itch shoulder with the the likes of of Archimedes while persist in his own erudition .
It was probably in the Library of Alexandria that he read about a queer upshot that take position in Syene ( now Aswan , Egypt ) at the summer solstice . Syene model to the south of Alexandria . At high noon , the sun would shine directly overhead and there would be no shadows stemming from the columns . However , Eratosthenes realized that at the same moment in Alexandria , columns clearly did have phantom . Being a good mathematician , he decide to utilize this knowledge to do a few calculation to figure out the circumference of the Earth .
To do this , Eratosthenes measured the shadower of an obelisk on June 21 at noon . He give away that the sun was about 7 ° 14′ from being direct overhead . He realized that , because the Earth is curved , the greater the curve , the longer the vestige would be .
free-base on his observations , he theorise that Syene must lie 7 ° 14′ along a curved shape from Alexandria . Furthermore , he knew that a circle take 360 ° , which meant that his calculation—7 ° 14’—was roughly one fiftieth of a roach . Therefore , Eratosthenes thought , if he multiplied the distance between Syene and Alexandria by 50 , he would have the circumference of the Earth .
The wanting data was simply how far by Syene was from Alexandria . He measured the aloofness in stadium . There is n’t an precise modern day conversion to stadia , and it is n’t absolutely clear which version of the stadia Eratosthenes was using , but regardless , from what is known , his estimation was remarkably accurate .
There are two theories as to how Eratosthenes project out the distance : first , that he hired a gentleman to walk there and numerate the steps . Second , that he heard a camel could go 100 stadia a day , and it took a camel about 50 daytime to trip to Syene . Whatever the case , he estimated the aloofness between Syene and Alexandria was 5,000 stadia . If that was the case , then using his formula , the earth was 250,000stadia around .
Due to the unsettled distance that stadium represents ( and peculiarly which stadia he was using ) , historian believe that Eratosthenes ’ finis was between .5 % and 17 % off the stain . Even if the latter case was true , it was astoundingly accurate give the limited technology he was cover with at the time . But many scholars think it likely that he was using the Egyptian sports stadium ( 157.5 m ) , being in Egypt at the clip . This would make his estimate only about 1 % too low .
There had been previous endeavour at strike the Earth ’s circuit ( which do n’t depend as “ first recorded ” because their method acting did n’t survive , though we have references to them ) which result in a 400,000 stadium figure , 150,000 more than Eratosthenes’—obviously far from exact .
While find the approximate circumference of the Earth was likely Eratosthenes ’ largest donation to eruditeness at the time , it was by no means the only one . Eratosthenes is also credited with coming up with a way to map out the known world by draw origin north - south and east - west — early parallel of latitude and longitude lines . However , these lines were irregular and often drawn through live post , meaning they were n’t entirely accurate . Nevertheless , it provided a precursor for mapping we know today .
He is also remembered for theSieve of Eratosthenes , a simple algorithmic program that nominate it easy to bump all prize numbers up to a certain limit . Though none of Eratosthenes ’ personal work on the sieve survives , he was credited with the creation of the algorithm by Nicomedes in his initiation to Arithmetic .
Not only that , but Eratosthenes estimated the distance to both the Lord’s Day and the Sun Myung Moon , and appraise the tilt of the Earth ’s axis vertebra all with amazing accuracy .
He also write the poem Hermes , aright chalk out the route of the Nile , and even gave a more - or - less exact account of why the Nile flooded , something that had stick scholars for one C . He worked on a calendar that include leap old age and he also count on and corrected the day of the month of various historical upshot beginning with the Siege of Troy .
Despite these accomplishments and many more like them , Eratosthenes was often nicknamed “ Beta . ” Beta is the 2nd letter in the Greek alphabet and referred to Eratosthenes being second - best in everything he did .
Eratosthenes died around 194 B.C. and is mean to have starve himself to last . It is believed that he lead off croak blind in his late class and , ineffective to continue his study , he merely stopped eating .
If you liked this article , you might also enjoy :
The Mysterious Fate of the Library of Alexandria
How the hurrying of Light was First Measured
Where Did The Time Go : The Phantom Time Hypothesis
How the Milky Way get Its Name and What It ’s Called in Other language
Why We Have a Seven Day Week and the Origin of the Names of the Days of the calendar week
Bonus Fact :
A Isle of Man named Posidonius copied Eratosthenes ’ basic method acting about a one C afterward , using the headliner Canopus , Rhodes , and Alexandria as starting points . However , he did n’t measure the aloofness between Rhodes and Alexandria right , lead in a perimeter that was smaller than Eratosthenes ’ estimation . It was this perimeter that was recorded by Ptolemy in his geography treatise and later on used by explorer looking for a quicker way to the Indies .
This posthas been republished with permit fromTodayIFoundOut.com .
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