I36 CENTRE OF GRAVITY CH. IX 



is therefore the position of the centre of gravity), 

 at a point 4 feet above the line joining the bottoms 

 of the wheels (that is, 4 feet from the ground when 

 the coach is standing level). The elevation of the 

 higher wheel is 2 ft. 10 in., and the inclination is 34 

 degrees. 



If the coach is loaded on top with twelve per- 

 sons, weighing together 1 700 pounds, the centre of 

 gravity of this additional load will be at the point 

 marked 1700; and the resultant centre of gravity 

 of that additional weight and of the empty coach, 

 will be at the point marked 4000, which is 5 ft. 6 

 in. from the bottom of the wheels, the whole weight 

 being 4000 pounds. 



If the coach is now tipped, the centre of gravity, 

 having been made higher, will come sooner into the 

 vertical line over the point of support, and the coach 

 will balance when the higher wheel is 2 ft. 4 in. from 

 the horizontal line or the inclination 27 degrees. 



It is evident that a very considerable elevation of 

 the road sideways is required to upset a coach at 

 rest, but it must be noticed that for some time be- 

 fore reaching the actual balancing point the coach 

 becomes very tender, to use a yachting expression. 

 For instance, in the case of the unloaded coach, 

 when the upper wheel was 2 ft. 6 in. from the floor, 

 the coach seemed on the point of balancing, al- 

 though 4 inches more elevation was actually re- 

 quired to make it do so. When, therefore, even a 

 slight horizontal force is acting on the coach, an 



