i8l3.] Imperial Institute of France. SIS 



state of our knowledge. We ought only to examine tliem with 

 an attention so much the more scrupulous, tliat it appears more 

 difiBcult to admit them. The same analysis may be extended to 

 the different results of medicine and political economy, and even 

 to the influence of moral causes ; for the action of these causes, 

 when it is repeated a great number of times, offers in its results 

 as much regularity as physical resuUs. 



" From these objects, which are particularly interesting to phi- 

 losophers, the author passes to objects of a more general inte- 

 rest, such as the problems of births. For example, he has found 

 that at Paris the proportion of males born to females is as 25 to 

 24; at London as 19 to 18 ; and in the kingdom of Naples, 

 not including Sicily, as 2-2 to 21. These ratios approach 

 equality, especially at Paris ; but in the three cities the number 

 of males exceeds ; and this result appears general, at least iu 

 Europe. 



" The births furnish one of the most simple and most proper 

 methods to determine the population of a great empire. It 

 gives for France a population of 42,529,267 individuals; and 

 the probabihty that the error of this statement does not exceed 

 half a million, is as 1161 to 1 ; that is to say, that we may 

 wager 1161 to 1 that the number is not below 42 millions, nor 

 above 43. 



The same formulas serve to calculate tables of mortaiit}^, to 

 show for every age the number of years of life which may be 

 expected ; the mean duration of marriages, or in general of 

 associations between two or more persons; finally, moral expec- 

 tations. 



Among the different objects which are treated in this work, 

 we have chosen those which are likely to excite the curiosity of 

 the greatest number of readers. Mathematicians will have no 

 choice to make : they will every where find skilful methods 

 united with observations the most ingenious. 



" Of the Defence of Strong Places', a work composed ly order 

 of his Imperial and Royal Majesty , for the instruciion cf the 

 eleves of the Corp dii Genie. By M. Cannot, ^d Edition. 



" We have formerly announced the first two editions of tlils 

 important work. The third is distinguished by a prc]in;inary 

 discourse, ip which the author shows the necessity of a];andoning 

 an imperfect system in order to adopt another, which the pro- 

 gress of the art of attack has rendered necessary ; and by two 

 chapters of great interest. One, which is the fourth of the 

 second part, is partly composed of an additional memoir inserted 

 in the second edition, hut which has received additions and de- 

 velopements that make it a new work : the other, which is the 

 fifth, presents the respective series of operations of attack and 

 defence, compared together from the comUienceiiient of the 

 siege to the end, 



