Update

history.md

@@ -12,6 +12,8 @@ Around 50 AD Heron of Alexandria, an Egyptian mathematician, created a number of
 
 In the 3rd century Chinese mathematician Liu Hui describes operations with **negative numbers**, even though negative numbers have already appeared before. In 600s AD an Indian astronomer Brahmagupta first used the number **[zero](zero.md)** in a systematic way, even though hints on the number zero without deeper understanding of it appeared much earlier. In 9th century the Mayan empire is [collapsing](collapse.md), though it would somewhat recover and reshape.
 
+In 1429 Persian mathematician al-Kashi computed [pi](pi.md) to about 14 digit accuracy which was a great leap in this discipline.
+
 Around the year of [our Lord](jesus.md) 1450 a major technological leap known as the **Printing Revolution** occurred. Johannes Gutenberg, a German goldsmith, perfected the process of producing books in large quantities with the movable type press. This made books cheap to publish and buy and contributed to fast spread of information and better education. Around this time the **Great Wall of China** is being built.
 
 They year 1492 marks the **discovery of America** by Christopher Columbus who sailed over the Atlantic Ocean, though he probably wasn't the first in history to do so, and it wasn't realized he sailed to America before his death.
@@ -28,7 +30,7 @@ In 1822 [Charles Babbage](charles_babbage.md), a great English mathematician, co
 
 In 1826 or 1827 French inventor Nicéphore Niépce captured **first [photography](photo.md)** that survived until today -- a view from his estate named Le Gras. About an 8 hour exposure was used (some say it may have taken several days). He used a [camera obscura](camera_obscura.md) and asphalt plate that hardened where the light was shining. Earlier cases of photography existed maybe as early as 1717, but they were only short lived.
 
-**Sound recording** with phonatograph was invented in 1857 in Paris, however it could not be played back at the time -- the first record of human voice made with this technology can nowadays be reconstructed and played back. It wouldn't be until 1878 when people could both record and play back sounds with  [Edison](edison.md)'s improvement of phonatograph. A year later, in 1879, Edison also patented the **light bulb**, even though he didn't invent it -- there were at least 20 people who created a light bulb before him.
+**Sound recording** with phonatograph was invented in 1857 in Paris, however it could not be played back at the time -- the first record of human voice made with this technology can nowadays be reconstructed and played back. It wouldn't be until 1878 when people could both record and play back sounds with  [Edison](edison.md)'s improvement of phonatograph. A year later, in 1879, Edison also patented the **light bulb**, even though he didn't invent it -- there were at least 20 people who created a light bulb before him. [Pi](pi.md) at this time is evaluated to roughly 500 digit accuracy (using Machin's formula).
 
 Around 1888 so called **war of the currents** was taking place; it was a heated battle between companies and inventors for whether the [alternating](ac.md) or [direct](dc.md) current would become the standard for distribution of electric energy. The main actors were [Thomas Edison](edison.md), a famous iventor and a huge capitalist dick rooting for DC, and George Westinghouse, the promoter of AC. Edison and his friends used false claims and even killing of animals to show that AC was wrong and dangerous, however AC was objectively better, e.g. by its efficiency thanks to using high voltage, and so it ended up winning the war. AC was also supported by the famous genius inventor [Nikola Tesla](tesla.md) who during these times contributed hugely to electric engineering, he e.g. invented an AC motor and Tesla coil and created a system for wireless transmission of electric power.