the time here given is the average, and private instruction and optional study hours are not included, it is easy to conceive that there must be a considerable number of boys who have to take more time for school-work.
How do children thus situated find time for meals, for rest, for exercise in the open air, for recreation, and, above all, for sleep? Must not their mental force be worn out and benumbed by such a burden, their physical growth and health suffer, and their capacity to resist unwholesome influences of every kind be diminished? There is no doubt about the answer. The mention of sleep raises a question of great importance to the rational teaching of children. We all know how much greater is the need of children for sleep than of grown persons, and how necessary for their good it is to be able fully to satisfy this need; but how great it is generally at any particular age of the child is very hard to define exactly. The amount varies under different climatic conditions. In Sweden, we consider a sleep of eleven or twelve hours necessary for the younger school children, and of at least eight or nine hours for the older ones. Yet the investigations have shown that this requirement lacks much of being met in all the classes, through the whole school. Boys in the higher classes get but little more than seven hours in bed; and as that is the average, it is easy to perceive that many of them must content themselves with still less sleep. It is also evident from the investigations that the sleeping time is diminished with the increase of the working hours from class to class, so that pupils of the same age enjoy less according as they are higher in their classes. It thus appears constantly that in schools of relatively longer hours of work, the sleeping time of the pupils is correspondingly shorter. In short, the prolongation of the working hours takes place for the most part at the cost of the time for sleep. If, then, the load of work of a school youth is too much for his stage of growth, and too little time is left for recuperation and sleep, the momentous question arises, whether it has been statistically proved that the length of the working time exercises a definite influence on the health of the children. It has. The average time of work of each class was computed, and the pupils were divided into two groups, consisting of those who studied more and those who studied less than the mean. It was found that the amount of illness of those who worked longer than the average was 5·3 per cent higher than that of those who worked less; a result which must be regarded as of very great importance when we consider how many other unhealthy influences there are to make themselves felt. The result was still more significant in the two lowest classes. The liability to illness there, in connection with the longer hours of work, was from 8·6 to seven per cent higher. We may also ob-
