BOOK VI. 

 INDUSTRIAL LABOUR. 



CHAPTER I. 



THE HUMAN BODY IN EQUILIBRIUM AND MOVEMENT. 

 LOCOMOTION. 



258. General Remarks. The study of Industrial Labour has 

 two main divisions. In the one we consider the human body 

 in equilibrium and in motion. In the other we investigate the 

 influence which is due to the nature and quality of the tools and 

 appliances employed. Herein we shall confine our attention 

 almost exclusively to the former division. 



The human body is an articulated, or jointed, system. But its 

 various members are not interconnected so as to form a rigid 

 whole like a marble statue. It is, indeed, never truly at rest. 

 When nominally in repose, the body is yet in continual movement 

 owing to the functions of respiration and circulation^ 1 ) The 

 muscles, also, being always more or less contracted, are in a con- 

 tinued state of vibration. The oscillatory movement due to 

 these vibrations can even be recorded if a style is fixed to the top 

 of the head ( 2 ), or, if a person is placed in a very sensitive 

 weighing machine, a periodical disturbance of equilibrium can 

 be detected. 



The human body is a material system subject both to exterior 

 forces (of which the most important is Gravitation) and also to 

 the interior forces of the muscles. Further, it is a heterogeneous 

 body, whose density varies in different parts. Its shape is irregu- 

 lar. Finally, it is not isolated in space, but is posed on the earth's 

 surface supported by a base formed by the feet. 



In short, the human body is a system to which the ordinary 

 laws of mechanics can be applied, and which can be studied both 

 in its static and dynamic states. 



(*) A. Mosso, Arch. Ital. Biol., vol. v., 1884. 



( 2 j Vierordt Grundriss d. Physiol. d. Menschen, p. 364, 1862, 2nd 

 edition. 



