CHAPTER V. 



Influence of Gravity constant. — Momentum accelerated. — The Law of Fall- 

 ing Bodies and its Application to Locomotion. — The nearer the Trajec- 

 tory OF the Centre of Gravity is to a Straight Line the more perfect 

 the Locomotion. — The Theory of Quadrupedal Locomotion stated. — Anal- 

 ysis of the Run. — The same in all the Domestic Animals.— The Bound of 

 the Deer. — Why the Flexor Tendons of the Fore Legs are more liable 

 TO be injured in the Run.— What is the Gallop ? — Objections of Artists 

 answered. — Truth must prevail over Conventionalism. — The Canter. 



The attraction of gravity, or that force which is constantly drawing 

 all bodies toward the centre of the earth, is a phenomenon so familiar 

 to us that we fail to realize it at all times, and the consequences that 

 would ensue were it to be for one moment suspended. Like the air 

 we breathe, it is one of the necessary conditions of our existence, and 

 the force with which it acts on all bodies is e.xactly measured by their 

 weio-ht; but this is the measure of that force in bodies in a state of 

 rest or inertia. The instant that support is removed and the body 

 yields to that force, there enters another element that must be taken 

 into account, and that is momentum. While gravity is a constant 

 quantity under similar conditions, momentum is a constantly varying 



one. 



By yielding to the force of gravity an object does not escape from 

 its power, neither is it reduced one grain in its influence at whatever 

 rate the body falls. It is therefore an increasing quantity in a rapid 

 ratio.* It is this force, which is constant and measured by the weight 



* The formula for the determination of the distance which a body will fall in any given 

 time \%,D = \gfi; in which D = distance ; "-, acceleration of gravity, or 32 feet ; /, time 

 in seconds. From this we learn that the distance which a body unsupported would fall in the 

 first \ second would be 4 feet ; in the first \ second, 7.68 inches ; in the first \ second, 3 inches. 



