$$229,230] Development of Gravitational Astronomy 291 



earth on Newtonian lines, and the appearance six years later 

 of Voltaire's extremely readable Elements de la Philosophic de 

 Newton had a great effect in popularising the new ideas. 

 The last official recognition of Cartesianism in France 

 seems to have been in 1740, when the prize offered by the 

 Academy for an essay on the tides was shared between 

 a Cartesian and three eminent Newtonians ( 230). 



The rapid development of gravitational astronomy that 

 ensued between this time and the beginning of the 

 1 9th century was almost entirely the work of five great 

 Continental mathematicians, Euler, Clairaut, D'Alembert, 

 Lagrange, and Laplace, of whom the eldest was born in 

 1707 and the youngest died in 1827, within a month of the 

 centenary of Newton's death. Euler was a Swiss, Lagrange 

 was of Italian birth but French by extraction and to a great 

 extent by adoption, and the other three were entirely 

 French. France therefore during nearly the whole of the 

 1 8th century reigned supreme in gravitational astronomy, 

 and has not lost her supremacy even to-day, though during 

 the present century America, England, Germany, Italy, and 

 other countries have all made substantial contributions to 

 the subject. 



If is convenient to consider first the work of the three 

 first-named astronomers, and to treat later Lagrange and 

 Laplace, who carried gravitational astronomy to a decidedly 

 higher stage of development than their predecessors. 



230. Leonhard Euler was born at Basle in 1707, 14 years 

 later than Bradley and six years earlier than Lacaille. He 

 was the son of a Protestant minister who had studied 

 mathematics under fames Bernouilli (1654-1705), the first of 

 a famous family of mathematicians. Leonhard Euler him- 

 self was a favourite pupil of John Bernouilli (the younger 

 brother of James), and was an intimate friend of his two 

 sons, one of whom, Daniel (1700-1782), was not only a dis- 

 tinguished mathematicianjike his father and uncle, but was 

 also the first important Newtonian outside Great Britain. 

 Like so many other astronomers, Euler began by studying 

 theology, but was induced both by his natural tastes and 

 by the influence of the Bernouillis to turn his attention to 

 mathematics. Through the influence of Daniel Bernouilli, 

 who had recently been appointed to a professorship at 



