Again, in five departments of France in which there is less than one hecatare to each inhabitant, that is to say, in which the population is more than 250 to the square mile, the number of births to 100 marriages is 414 and a fraction. But in the four counties of England in which the population is from 200 to 250 on the square mile, the number of births to 100 marriages is, according to one of Mr Sadler's tables, only 388, and by his very highest estimate no more than 402. Mr Sadler gives us a long table of all the towns of England and Ireland, which, he tells us, irrefragably demonstrates his principle. We assert, and will prove, that these tables are alone sufficient to upset his whole theory. It is very true that, in the great towns the number of births to a marriage appears to be smaller than in the less populous towns. But we learn some other facts from these tables which we should be glad to know how Mr Sadler will explain. We find that the fecundity in towns of fewer than 3000 inhabitants is actually much greater than the average fecundity of the kingdom, and that the fecundity in towns of between 3000 and 4000 inhabitants is at least as great as the average fecundity of the kingdom. The average fecundity of a marriage in towns of fewer than 3000 inhabitants is about four; in towns of between 3000 and 4000 inhabitants it is 3.60. Now, the average fecundity of England, when it contained only 160 inhabitants to a square mile, and when, therefore, according to the new law of population, the fecundity must have been greater than it now is, was only, according to Mr Sadler, 3.66 to a marriage. To proceed,--the fecundity of a marriage in the English towns of between 4000 and 5000 inhabitants is stated at 3.56. But, when we turn to Mr Sadler's table of counties, we find the fecundity of a marriage in Warwickshire and Staffordshire rated at only 3.48, and in Lancashire and Surrey at only 3.41. These facts disprove Mr Sadler's principle; and the fact on which he lays so much stress--that the fecundity is less in the great towns than in the small towns--does not tend in any degree to prove his principle. There is not the least reason to believe that the population is more dense, ON A GIVEN SPACE, in London or Manchester than in a town of 4000 inhabitants. But it is quite certain that the population is more dense in a town of 4000 inhabitants than in Warwickshire or Lancashire. That the fecundity of Manchester is less than the fecundity of Sandwich or Guildford is a circumstance which has nothing whatever to do with Mr Sadler's theory. But that the fecundity of Sandwich is greater than the average fecundity of Kent,--that the fecundity of Guildford is greater than the average fecundity of Surrey,--as from his own tables appears to be the case,--these are facts utterly inconsistent with his theory.