BONES, MUSCLES, EXERCISE, AND REST. 



317 



stress bends her chest forward over her sewing, or if the erj- 

 graver or watchmaker has his bench so low that the spine 

 must be curved forward to bring himself near to his work, 

 and if they sit in this manner for months and years, the car- 

 tilages are compressed beyond the power of reaction. The 

 front part is flattened and the back part is thickened ; it 

 becomes wedge-shaped, and consequently the back-bone is 

 permanently crooked, and the person stoops or is rourid- 

 shouldered. 



730. The same law applies to the lateral line of the back- 

 bone, and similar habits of compression of the cartilages 

 bring on curvatures from side to side. The position assumed 

 at school while writing, (Fig. LX.) and often while studying, 

 throws the spine out of its straight, lateral line, and bends it 

 to one side or the other. The table or desk for writing or 

 FIG. LX. Fm. LXI. 



drawing is usually higher than the elbow, as it hangs from 

 the shoulders of the pupil sitting on the seat. In order, then, 

 to write or draw, the right arm and elbow are raised and rested 

 upon the elevated table. This raises the right shoulder, and, 

 in raising it, bends the upper part of the spine over from 

 the right to the left, and depresses the left shoulder. Then. 

 27 * 



