Energy 9 



pipe in a unit of time. We, therefore, speak 

 of electrical energy as being measured by 

 volume and pressure. In a similar way we 

 may illustrate the energy residing in the 

 organs of an animal by comparing it with the 

 quantity of air in a receptacle. In this case 

 the quantity of air would be the product of its 

 volume and its pressure. The quantity of 

 energy in an organ would be the product of 

 the volume of the organ and potential at 

 which it existed in the organ. Or we may 

 consider the cells of an organ as being so 

 many accumulators (storage batteries) in 

 which organic energy is continually being 

 stored and from which it is discharged as 

 wanted. The work performed by an animal 

 is most easily measured by force, velocity, 

 and time, while we obtain our best conception 

 of energy within an animal available for 

 performing work by considering its volume 

 and potential. 



The definition which states that energy 

 is an attribute of matter is incorrect, because 

 the amount of energy in a given body of 



