ON ACCIDENTS. 303 



carry. Many broken limbs and fatal accidents would be 

 avoided by their more general adoption. 



All general rules are commonly denominated laws : 

 thus the general rules which bodies observe in the com- 

 munication of motion, are called the laws of motion. 

 Now, without troubling you with the demonstrations of 

 mathematicians, I shall content myself with observing 

 that, by the laws of gravity, falling bodies, i.e. bodies 

 falling by their own weight, near the surface of the 

 earth, double the velocity of their fall in a second of 

 time, By this I mean that a stone which falls sixteen 

 feet in one second, may acquire the velocity of thirty-two 

 in another, and so on in arithmetical progression. This 

 is the simple effect of the power of gravity acting on the 

 stone, which shows that, excluding the consideration of 

 the air's resistance, the velocity of falling bodies is pro- 

 portionate to the time of their fall. Now, as the action 

 of gravity is continual, so by the doctrine of projects a 

 coach descending a hill must acquire fresh impulse every 

 yard she goes, and of course descends with accelerated 

 velocity. When all this is added to the well-known fact, 

 that as much force is required to put a body which is in 

 motion at rest, as there is to set a body which is at rest 

 into motion, the numerous accidents which happen to 

 coaches, in descending hills, are easily accounted for. 

 What I have now stated also confirms the necessity I 

 have insisted upon of checking the active force of a 

 coach before she begins to descend a steep hill ; and, 

 indeed, I may say, in some cases — as with bad holders — 

 before she comes upon a descent which can scarcely be 



