=Distribution of the Pupils in a School.=--To put into practice the principle which we have just formulated, a circular is distributed to the schools asking the head-masters to arrange the children in each class according to age upon a blank table furnished to them. The work is easy, and the return should be required in a maximum period of eight days. Within this period twenty elementary schools in Paris supplied us with the information which we asked for through their inspectors. We give one of these returns, which we shall examine briefly, insisting only on the essential points. We ask, then, that on the table, of which a blank copy is supplied, the head-master shall give the number of children who on October 1--that is to say, the first day of the session--were of such and such an age--_e.g._, six or seven years. The normal ages for the different courses or standards are as follows: Preparatory or infant 6 to 7 years of age. Elementary, first year 7 to 8 " " Elementary, second year 8 to 9 " " Intermediate, first year 9 to 10 " " Intermediate, second year 10 to 11 " " Senior, first year 11 to 12 " " Senior, second year 12 to 13 " " Thus a child is "regular" in instruction when he is found in the class named at the age indicated. The normal age for the infant class is from six to seven years. The children of that age are entered in the table in the appropriate column. Now consider the extreme ages between six and seven which obey this condition. On the one hand would be a child exactly six years of age on admission. Such a child is exactly normal as regards age. He is behind by 0 years, 0 months, 0 days. At the other extreme would be a child exactly seven--or, rather, one day less than seven--on admission. Such a child would be behind by exactly one year. Consequently, the column headed six to seven years for the infant class contains children behind by 0 day as a minimum, and one year as a maximum. The average will therefore be behind by six months (compared to the ideal). Analogous reasoning would show that the children of the infant class entered in the column headed five to six years would, on the average, be six months in advance of their age. Similarly, those shown in the column headed seven to eight years would be on the average one and a half years behind.