O'Reilly logo

The Geek Atlas by John Graham-Cumming

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

008

The Arago Medallions, Paris, France

missing image file48° 504.23N, 2° 20 11.41 E

icon_food.pdf icon_free.pdf

François Arago and the Paris Meridian

François Arago was a French mathematician, physicist, and astronomer (and briefly the Prime Minister of France in 1848) who studied optics, magnetism, electricity, and astronomy. He strongly supported the then-controversial theory that light was made up of waves; he demonstrated that a rotating metal disc affects the motion of a magnetic needle suspended above it (for more on magnetism, see Chapter 75); and he showed that light moves more slowly in dense media. He was also a popular orator, and gave public lectures on astronomy for over 30 years.

But Arago is best known today as one of the directors of l’Observatoire de Paris (the Paris Observatory), where he lived and worked. The Observatory was established in 1667 with the support of King Louis XIV of France. Initially, the Observatory’s mission was to improve the instruments and maps needed for marine navigation. On Midsummer’s Day in 1667, the outline of the Observatory was traced on the ground, with measurements being made to determine the location for the Paris meridian. The Paris meridian (and hence the French definition ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required