Displaying Information Maps and Graphs

Not all those who contributed to the culture of information were members of the bourgeoisie. In the area of visual representation, two names—Cassini and Harrison—illustrate how widely the culture of information had spread to all classes of society. For over a century, four generations of Cassinis dominated French astronomy and cartography. The founder of this illustrious lineage, Giovanni Domenico Cassini (1625 –1712), was a professor of astronomy at the University of Bologna when he was recruited to head the Paris Observatory in 1669. He became a French citizen, changed his name to Jean-Dominique Cassini, and entered into the privileged elite of the Old Regime. At the observatory, Jean Cassini discovered the rotation of the planets and developed a method of determining longitude by sighting the moons of Jupiter. He also launched the most elaborate cartographic project of his time, the map of France known as “la carte de Cassini.” His son Jacques Cassini (1677–1756), known as Cassini II, succeeded him at the observatory and as a member of the French Academy of Sciences. Jacques carried on his father’s work of measuring the arc of the meridian—a necessary but preliminary step in constructing an accurate map of France. In this effort, which was to take fifty years, Jacques Cassini was seconded by his son César-François Cassini de Thury (1714 –1784), known (of course) as Cassini III, who was also a member of the Academy and director of the observatory. When César-François died in 1784, his son Jacques-Dominique (1748 – 1845), count of Cassini (Cassini IV), carried on as head of the observatory, member of the academy, and director of the map project. The Cassinis’ Carte de France, completed in 1793, was a masterpiece of Old Regime cartography. Jacques­ Dominique’s son Gabriel (1784 –1832) broke with the family tradition and became a botanist. In contrast to this story of distinction and privilege, John Harrison’s life was one of struggle and hardship, rewarded by success only at the very end. Harrison (1693 –1776) was the son of a carpenter who taught himself how to build clocks.