THE INSTITUTE OF FRANCE 15 



the entire horizon. An attempt was made at that time to fix the 

 meridian line, but this was done more accurately by James Cassini, son 

 of J. D. Cassini, in 1733. Imperfect as were their instruments, large 

 sums of money were expended on them, and excellent work was done. 

 The principal marvels of the heavens were discovered, the sun's rota- 

 tion on itself, the revolution of Mars, Venus and Jupiter, the nebula?, 

 variable stars, four of Saturn's satellites and the division of his ring. 

 Cassini's atlas of the heavens of sixty-two pages or plates was 

 graciously accepted by the king as a gift from the astronomer. Huy- 

 ghens of Holland succeeded Cassini as director of the observatory and 

 be was followed by Roemer, the Dane, who discovered the velocity of 

 light. Although after the death of Colbert in 1683 the resources of 

 the observatory were diminished, the astronomers continued their work 

 and by their discoveries brought fame to the nation. After 1GS9 and 

 for many years, it is said, their salaries were only one third of what they 

 had been in the time of Colbert. 



The work of the astronomers of the seventeenth and eighteenth 

 centuries has sometimes been treated as of small importance. But it 

 was as good as the means for the study of the heavens permitted. The 

 French astronomers, according to the testimony of Airy of England, 

 did the best work in the world. Their efforts to measure accurately a 

 degree of the meridian attracted universal notice. In this work the 

 Abbe Picard was prominent. J. D. Cassini, his son James, Philippe 

 de la Hire and a few others visited India and America to secure favor- 

 able observations. In 1755 Godin, Bougner and la Condaminer went 

 to Peru, Maupertuis and Clairvant to Laponie, le Maurier and the 

 Abbe de la Caillet to the Cape of Good Hope. The transit of Venus 

 in 1761 was observed with great care. The abbe Chappe d'Auteroche 

 went to Tobolsk, Francis Cassini de Maury to Venice, and Pingre to 

 the island of Eodriguez. Observations were also made at San Jose, 

 California. In 1769 other observations of the transit were made, but 

 war with the English prevented some that might have been very 

 valuable. 



In 1770 the condition of the observatory was discouraging. Re- 

 ports were to the effect that it was dangerous to occupy the buildings. 

 The ministers of Louis XVI. aided J. D. Cassini de Thury in his work. 

 But perfect instruments and promised repairs of the buildings were 

 insufficient to persuade Cassini to remain in Paris after the Revolution 

 and the decree of 1791. In June of this year the convention turned 

 over all the observatories of France to the Bureau of Longitude. Under 

 the influence and direction of such men as Laplace, Delambre, Legendre, 

 Lagrange, Michain, Arago, Bouvard and his son, Mathieu and Mauduis 

 the observatory regained its former reputation and even added to it. 

 Still, as late as 1832, the astronomers found it neither altogether safe 

 nor comfortable to live in the quarters provided for them. 



