Professor Shaler's article in the current number of the Atlantic Monthly is indeed interesting. He makes some striking remarks on the difference between the strain caused by mental and physical exercise, showing by the use of statistics how very great is the mental strain under which the teacher or literary man labors. The agriculturist, the artisan and the professional man in general who is not engaged in teaching the youth, are accustomed to continuous toil for at least ten hours daily six days in the week. With the instructor it is quite different; about one third of the year is spent in rest or in ways not directly connected with instruction, and besides, when employed, his day is shorter than other laborers. With this as a basis, an argument is made which goes to prove the reasonableness of the great difference in the number of hours that the brain worker can profitably labor, and that demanded of the man engaged in physical labor. The reason is this: nature has so constructed man that his physical powers of endurance greatly exceed his mental endurance.
On investigation Professor Shaler has found that many laboring men and women exceed two hundred thousand hours of hard work in a life-time while the average time of life spent by our most laborious literary men has not exceeded thirty thousand hours or about one sixth that of the laboring man with only as much brain as may guide his movements. Inasmuch, therefore, as intellectual labor his been found more wearying than that required of the ordinary man, the conclusion has been drawn that not more than nine months of the year should be devoted to school work, and it seems to be the tendency everywhere to increase rather than diminish the periods devoted to refreshment. These respites from intellectual labor are not unaccompanied by evil tendencies, and, in fact, the mind needs some time in which to be restored to its normal condition. The question proposed in this article is "How may this evil be counteracted?" Professor Shaler then refers to the summer schools of science which seem to him to offer a solution, and he gives some account of the manner in which they are conducted in the University. These summer classes are growing in numbers yearly, and if they prove all that Professor Shaler thinks, such schools will soon be established at other educational institutions.