CARRIA GE-SPRIXGS. 391 



calculations are of American origin, I decline to make 

 use of them. 



I am afraid that there has been a good deal of 

 repetition in this chapter, but in referring to many 

 opinions it is difficult to avoid a certain amount of 

 repetition, particularly when comparing opinions ex- 

 pressed by others with that which I myself entertain ; 

 besides which I have been anxious to lay emphasis 

 upon certain points in connection with coach-building, 

 more especially that which refers to w^heels and axles. 

 I wish the attributes of the two axles in general use 

 to be thoroughly understood, for it is upon wheels, 

 axles, and the pole that the safety of a coach mainly 

 depends. 



The common axle which I have referred to else- 

 where, is not worthy of consideration when speaking of 

 carriage-building, it being only used on vehicles of a 

 very inferior class. 



As regards springs it may be mentioned that they 

 not only contribute to the comfort of persons driving 

 in a carriage, but they also assist draught and lessen 

 the fatigue of the horses employed to draw a carriage. 

 Their object is- to yield to the rise and fall of the 

 wheel when passing over the inequalities of the road 

 so that the body may not be affected by them, and 

 that the concussion may be sensibly diminished ; in 

 consequence of which the horses will go more at their 

 ease, and not be made to suffer by constant jolts and 

 jerks whilst they are exercising their powers in draw- 

 ing the vehicle to which they are attached. There 

 are many varieties of springs, but they may be com- 

 prised under two distinct heads ; first, those in which 

 steel only is used as the elastic material, such as the 

 ordinary elliptic and grasshopper spring ; and, secondly, 

 those in which it is aided by leather straps as in the 



