364 



THE HUMAN MOTOR 



If h is the total height of the stair we have 



T = P X h. 

 If the man carries a load Q 



T' = (P + Q)h. 



^ In walking upstairs the lateral swayings of the body are ex- 

 aggerated. In a rapid ascent there is certainly a slight vertical 

 oscillation. This can be detected by watching the shadow of the 

 climber on the wall of the staircase. 



j 278. In walking up an inclined plane, the conditions are a 

 combination of those found in ascending a stairway and in 

 walking on the level. The front leg B (fig. 259) is necessarily 



Walking on an inclined plane. 



bent, so that OCB' --= OB, the body being bent forward to 

 counteract the tangential component of the force of Gravity. 

 As the rear leg becomes vertical it lifts the weight of the body 

 through a distance DD' (vide fig. 260) This distance is equal to 



Fio. 260. 



