on a vertical plane. The measuring-tape gives false indications of the dimensions of the thorax, for its measurements are influenced by the muscular protuberances. We have substituted for gross measurements of the circumference of the thorax those of diameters obtained with compasses and thoracometers specially constructed to give the amplification of the framework of the chest in respiration. With these exact means, and the assistance of physicians who are all interested in these questions, we hope to organize in schools a series of measurements that will cast light on many obscure points. Data are wanting for the definition of the characteristic differences in the form of different subjects whose movements have been accommodated to a special and well-defined profession; and those data in particular are wanting with which to establish the laws of the development of children according as they have or have not been subjected to physical exercise under various conditions. We have begun investigations on this point at the Collége Sainte-Barbe, with the aid of M. Rey, and at the school of Joinville le Pont, with that of M. Roblot. We have found that with growing children the increase of the respiratory capacity is parallel with that of the weight, and has no fixed relation with the stature; and we have shown that the ratio of the respiratory capacity to the weight increases regularly under training. We find also that the absolute dimensions of the thorax do not increase among adults, but that the extent of the movement of the ribs is related to the respiratory capacity. It is, for the same subject, parallel with the quantity of air breathed in. M. Marey showed, some time ago, that the thoracic movements of subjects under exercise are amplified, while their frequency diminishes. Respiration becomes fuller and remains so during rest or after intense exercise. By collating observations bearing on this point, we shall be able to constitute a kind.of experimental physiology of exercise, and shall thus have the best and only means of pronouncing without prepossession upon the value, as to the general development of the body, of different methods of education.
We now proceed to examine the tendencies of exercise in view of the economical utilization of muscular strength. The third essential point in physical education consists in establishing the rules that permit the useful and economical employment of muscular force in the various conditions of locomotion, in the management of tools and arms, and in carrying burdens. This is one of the most delicate chapters of animal mechanics. It is the one that is really entitled to be designated the education of the movements, for the educator plays the greatest part in it, and his action is indisputable. When one has devoted himself for a long time to practical exercises of the body, especially to varied exer-
