472 THE POPULAR SCIENCE MONTHLY. 



nastic matters. The form of the curvings of the vertebral column 

 depends on the action of the weight and of the antagonistic mus- 

 cles that bend and extend it. There is an evident relation be- 

 tween the curves of the vertebral column and the form of the 

 thorax ; with large curvatures correspond depression of the ribs, 

 and enfeebling of the thorax and its consequences obstruction of 

 the circulation and of pulmonary ventilation. 



The respiratory capacity of a person does not depend on the 

 absolute volume of the throat, but on the extent to which its 

 volume increases between expiration and inspiration. The lung 

 is the slave of the thoracic wall, and follows it in all its move- 

 ments. It is constantly kept in contact with that wall, through 

 the action of the atmospheric pressure, which is transmitted to 

 the interior of the bronchise, whenever the glottis is opened. Ex- 

 cept under stress of effort, we can not imagine the lung pushing 

 upon the thoracic wall to dilate it ; the contained has to submit 

 to the variations of the containing. Hence, we have no reason to 

 wonder that gymnasts are soon able, by training, to increase their 

 respiratory capacity by giving, through the motions of the upper 

 limbs, a great mobility to the articulations of the thorax, and 

 thus permitting it to dilate more freely under the action of the 

 elevator muscles of the ribs, to the effect of which is added that 

 of the diaphragm. By strengthening the shoulder and fixing 

 the omoplate with strong muscles, we furnish points of support, in 

 raising the ribs and the flattened thorax. The action of the mus- 

 cles of the abdominal walls counterpoises that of the extensors 

 of the trunk, and the spine is raised by diminishing its curvatures 

 under the effect of these two kinds of curves acting upon it as 

 upon a bow with two curves. Thus, by perfecting the muscular 

 powers and bringing them into equilibrium, the trunk assumes 

 a good attitude, the chest expands, and the man bears the external 

 indications of vigor and health. % All these observations are facts 

 demonstrated and known by practitioners, who have obtained 

 them through good gymnastics. They show that there is a direc- 

 tion to be given to exercises having a good result in view, and 

 that the purpose of physical education will be more quickly 

 attained as the methods are more precise. Stirring around in an 

 indeterminate way is certainly not the shortest and most direct 

 means of obtaining the essential modifications sought for. 



We have attached so much importance to that part of the 

 hygiene of exercise that bears upon the form, that we have had 

 constructed at the physiological station, with the assistance of M. 

 Otto Lund, an arsenal of instruments of measurement of a new 

 kind. Some of these instruments give the height, weight, and 

 outline in true size of the fore and back curvatures of the spine ; 

 others furnish complete sections of the trunk on a horizontal and 



