S4i4i BUFFON". 



642. We have now to examine a contribution to our subject 

 from the illustrious naturalist Buffon whose name has already- 

 occurred in Art. 85 -i. 



Buffon's Ussai d' Arithmetique Morale appeared in 1777 in the 

 fourth volume of the Supplement a VHistoire Naturelle, where it 

 occupies 103 quarto pages. Gouraud says on his page 54, that the 

 Essay was composed about 1760. 



643. The essay is divided into 35 sections. 



Buffon says that there are truths of different kinds ; thus there 

 are geometrical truths which we know by reasoning, and physical 

 truths which we know by experience ; and there are truths which 

 we believe on testimony. 



He lays down without explanation a peculiar principle with 

 respect to physical truths. Suppose that for n days in succession 

 the Sun has risen, what is the probability that it will rise to- 

 morrow ? 



Buffon says it is proportional to T~^. See his 6th section. 



This is quite arbitrary ; see Laplace Theoine. . .des Prob. page XIII. 



644. He considers that a probability measured by so small 

 a fraction as cannot be distinguished from a zero proba- 

 bility. He arrives at the result thus ; he finds from the tables 

 that this fraction represents the chance that a man 56 years 

 old will die in the course of a day, and he considers that such 

 a man does practically consider the chance as zero. The doctrine 

 that a very small chance is practically zero is due to D'Alembert ; 



see Art. 472 : Buffon however is responsible for the value Yoooo ' 

 see his 8th section. 



645. Buffon speaks strongly against gambling. He says at 

 the end of his 11th section : 



Mais nous aliens donner un puissant antidote centre le mal ^pi- 

 demique de la passion du jeu, et en meme-temps quelques priservatifs 

 centre rillusion de cet art dangereux. 



He condemns all gambling, even such as is carried on under 

 conditions usually considered fair ; and of course still more 



