Problem: Eratosthenes of Cyrene (; Greek: Eratosthenes o Kurenaios, IPA:

Eratosthenes now continued from his knowledge about the Earth. Using his discoveries and knowledge of its size and shape, he began to sketch it. In the Library of Alexandria he had access to various travel books, which contained various items of information and representations of the world that needed to be pieced together in some organized format. In his three-volume work Geography (Greek: [Geographika] ), he described and mapped his entire known world, even dividing the Earth into five climate zones: two freezing zones around the poles, two temperate zones, and a zone encompassing the equator and the tropics. He had invented geography. He created terminology that is still used today. He placed grids of overlapping lines over the surface of the Earth. He used parallels and meridians to link together every place in the world. It was now possible to estimate one's distance from remote locations with this network over the surface of the Earth. In the Geography the names of over 400 cities and their locations were shown: this had never been achieved before. Unfortunately, his Geography has been lost to history, but fragments of the work can be pieced together from other great historians like Pliny, Polybius, Strabo, and Marcianus. The first book was something of an introduction and gave a review of his predecessors, recognizing their contributions that he compiled in the library. In this book Eratosthenes denounced Homer as not providing any insight into what he now described as geography. His disapproval of Homer's topography angered many who believed the world depicted in the Odyssey to be legitimate. He also commented on the ideas of the nature and origin of the Earth: he had thought of Earth as an immovable globe; while on its surface was a place that was changing. He had hypothesized that at one time the Mediterranean was a vast lake that covered the countries that surrounded it; and had only become connected to the ocean to the west when a passage had opened up sometime in its history. In the second book is his discovery about the circumference of the Earth. This is where, according to Pliny, "The world was grasped." Eratosthenes described his famous story of the well in Syene, described above. This book would now be considered a text on mathematical geography. His third book of the Geography contained political geography. He cited countries and used parallel lines to divide the map into sections, to give accurate descriptions of the realms. This was a breakthrough, and can be considered the beginning of geography.

How was he able to make such accurate calculations?

Answer with quotes: He created terminology that is still used today. He placed grids of overlapping lines over the surface of the Earth.

Problem: David Jon Gilmour, (born 6 March 1946) is an English guitarist, singer and songwriter best known as a longtime member of the progressive rock band Pink Floyd. He joined the group as guitarist and co-lead vocalist in 1968, effectively as a replacement for founder member Syd Barrett, who was dismissed from the band shortly afterwards. Pink Floyd subsequently achieved international success with the concept albums The Dark Side of the Moon, Wish You Were Here, Animals, and The Wall. By the early 1980s, they had become one of the most critically acclaimed and best-selling acts in the history of popular music; it was estimated that by 2012 the band had sold over 250 million records worldwide, including 75 million units sold in the United States.

Gilmour was responsible for bringing Kate Bush to public attention. While she was still at school, her family produced a demo tape with over 50 of her compositions, which was turned down by record labels. Gilmour received a copy of the demo from Ricky Hopper, a mutual friend of Gilmour and the Bush family. Impressed with what he heard, Gilmour helped the sixteen-year-old Bush get a more professional-sounding demo tape recorded that would be more saleable to the record companies. Three tracks in total were recorded and paid for by Gilmour. The tape was produced by Gilmour's friend Andrew Powell (who would go on to produce Bush's first two albums) and sound engineer Geoff Emerick. Gilmour then arranged for EMI executive Terry Slater to hear the tape. Slater was impressed by the tape and signed her. Gilmour is credited as executive producer on two tracks on her debut album The Kick Inside, including her second single "The Man with the Child in His Eyes". He performs backing vocals on "Pull Out the Pin", on her fourth album, The Dreaming, and plays guitar on "Love and Anger" and "Rocket's Tail" on her sixth, The Sensual World. In March 1987, Bush, notorious for the rarity of her live performances, sang "Running Up That Hill" at The Secret Policeman's Third Ball with Gilmour on guitar. A three DVD set of The Secret Policeman's Balls benefit concerts that includes their performance was released in 2009. In 2002, she performed "Comfortably Numb", singing the part of the doctor, at Gilmour's concert at the Royal Festival Hall in London.

Who is Kate Bush?

Answer with quotes:
Gilmour was responsible for bringing Kate Bush to public attention. While she was still at school,