196 Scientific Intelligence. — Anthropology. 



century. By this method, which embraced the whole century, 

 and which avoided the special circumstances of the inhabitants 

 as to their place of residence, their station in society, and the 

 order of birth of their children, the author collected, 1^^, 482 

 observations, from which there results, that, in Paris, during 

 the eighteenth century, to the time of marriage, the mean age 

 of a man has been 29 years QS hundredths, and that of a woman 

 24 years 72 hundredths ; and that thus the difference of age be- 

 tween the two engaging parties has been, as a mean term, 4 

 years 96 hundredths. 9>dly, With respect to the generation of 

 a family, M. Villot procured 505 observations for the male sex, 

 and 486 for the female. These latter shew, that, in Paris, du- 

 ring the eighteenth century, up to the period of birth of a son, 

 the mean age of a mother was 28 years 17 hundredths ; while, 

 from 505 observations relative to the male sex, there results, 

 that, in Paris, during the same century, the mean age of a fa- 

 ther, at the period of the birth of a son, was 33 years 31 hun- 

 dredths. This interval representing the duration of a male ge- 

 neration, it follows that there have been about three generations 

 at Paris in the eighteenth century. M. Villot remarked, that 

 this duration coincides with that which was adopted by the 

 Greeks in their chronological calculations, — a remarkable result, 

 if we consider the difference of manners of the two nations, and 

 of the climate of the two countries. In order to determine the 

 degree of confidence which the mean numbers obtained by his 

 observations merit, M. Villot has applied 'to his investigation a 

 rule of M. Fourier''s, calculated to make known the limit of the 

 error which a mean value furnished by a certain number of ob- 

 servations may present ; and there results from this application, 

 that the limits of the mean of these numbers do not exceed two 

 months, more or less ; and hence, that these numbers are the true 

 expression of the mean value sought, since it is certain that, by 

 repeating this operation, a great number of times, and by com- 

 paring together the numbers obtained by the new operations, it 

 would turn out that the number which would express the union 

 of all those which would surpass the value in question, di- 

 vided by the number expressing the union of those which would 

 be beneath that same value, would give for a quotient unity, or 

 a fraction very near unity ; or, in other terms, that the probabi- 



