The Laws of Motion. 231 



when that line falls without the base. Thus the 

 body A (fig. 94.) slides down the inclined plane 

 C D, while the body B rolls down upon it. 



The broader the base the firmer any body 

 stands ; thus you find you stand firmer with your 

 feet a little asunder than when close together ; 

 and in the former case it will require a much 

 greater force to push you down. Hence the advan- 

 tage of walking with the feet rather wide asunder, 

 on a slippery pavement in frosty weather. When- 

 ever the line of direction, however, falls without 

 the base of our feet, we necessarily fall ; " and 

 it is not only pleasing," says Mr. Ferguson, 

 " but even surprising, to reflect upon the various 

 and unthought-of methods and postures which 

 we use to retain this position, or to recover it 

 when it is lost. For this purpose we bend our 

 body forward when we rise from a chair, or when 

 we go up stairs: and for this purpose a man 

 leans forward when he carries a burden on his 

 back, and backwards when he carries it on his 

 breast ; and to the right or left side as he carries 

 it on the opposite side." A thousand more in- 

 stances might be added, but they will readily 

 suggest themselves to the mind of reflecting 

 persons. 



