The Paris Meridian is the name of the line running north-south through the astronomical observatory in Paris. One of the original intentions behind the founding of the Paris Observatory was to determine and measure this line. The French government financed the Paris Academy of Sciences to do so in the seventeenth to nineteenth centuries. It employed both astronomers - people who study and measure the stars - and geodesists - people who study and measure the Earth. This book is about what they did and why.This is the first English language presentation of this historical material. It is attractively written and it features the story of the community of scientists who created the Paris Meridian. They knew each other well - some were members of the same families, in one case of four generations. Like scientists everywhere they collaborated and formed alliances; they also split into warring factions and squabbled. They travelled to foreign countries, somehow transcending the national and political disputes, as scientists do now, their eyes fixed on ideas of accuracy, truth and objective, all enduring values - yet when the reception given to their own work was concerned some became blind to high ideals and descended into petty politics.To establish the Paris Meridian, the scientists endured hardship, survived danger, and gloried in amazing adventures during a time of turmoil in Europe consisting of the French Revolution and the Napoleonic War between France and Spain. Some were accused of witchcraft. Some of their associates lost their heads on the guillotine. Some died of disease. Some won honor and fame. One became the Head of State in France. Some found dangerous love in foreign countries. One scientist was killed in self defence when attacked by a jealous lover, another was himself killed by a jealous lover, a third brought back a woman to France and then jilted her, whereupon she joined a convent... The scientists worked on practical problems of interest to the government and to the people. They also worked on one of the most important intellectual problems of the time, a problem of great interest to their fellow scientists all over the world- the theory of universal gravitation. They succeeded in their intellectual work while affecting politics and the affairs of state; their endeavours have left marks on the landscape, in art, and in literature still visible today.