56 DISSERTATION SECOND. [part ir. 







the fluctuation 1 of her opinions, it seems as if she had not jet 

 entirely exchanged the caprice of fashion for the austerity of 

 science. About the same time Voltaire engaged in the argu- 

 ment, and in a Memoire, 2 presented to the Academy of Sci- 

 ences in 1741, contended that the dispute was entirely about 

 words. His reasoning is on the whole sound, and the suf- 

 frage of one who united the character of a wit, a poet, and a 

 philosopher, must be of great importance in a country where 

 the despotism of fashion extends even to philosophical 

 opinion. 



The controversy was now drawing to a conclusion, 3 and in 

 effect may be said to have been terminated by the publica- 

 tion of D'Alembert's Dynamique, in 1743. I am not certain, 

 however, that all the disputants acquiesced in this decision, 

 at least till some years later. Dr. Reid, in an essay On 

 Quantity, in the Philosophical Transactions for 1748, has 



1 Mad. du Chastellet, in a Dissertation on Fire, published -in 

 1740, took the side of Mairan, and bestowed great praise on his; 

 discourse on the force of moving bodies. Having, however, 

 afterwards become a convert to the philosophy of Leibnitz, she 

 espoused the cause of the Vis Fiva, and wrote against Mairan. 

 At this time too she drew up a compend of the Leibnitian philo- 

 sophy for the use of her son, which displays ingenuity and acute- 

 Bess, and is certainly such a present as very few mothers have 

 ever been in a condition to make to their children. Soon after- 

 wards the same lady, having become a Newtonian, returned to 

 her former opinion about the force of moving bodies, and in th 

 end, gave to her countrymen an excellent translation of the 

 Principia of Newton, with a commentary on a part of it, far 

 superior to any other that has yet appeared. 



3 Doutes sur In Mcsure des Forces Matrices ; CEuvres de Vol- 

 taire, Tom. XXXIX. p. 91. 8vo. edit. 1785. 



3 Two very valuable papers that appeared at this late period 

 of the dispute are found in the Philosophical Transactions ; one 

 by Desaguliers, in 1733, full of excellent remarks and valuable 

 experiments ; another by Jurin, in 1745, containing a very full 



...' of the whole controversy. 





