2 



THE ANIMAL AS A MACHINE. 



transformations of energy, as where a steam boiler 

 transforms, and stores for transmission to the engine, 

 energy of chemical affinity ; the engine, in turn, trans- 

 forming it into mechanical energy and transmitting it 

 to a dynamo-electric machine, where it is again trans- 

 formed, changing into the electrical current, to be sent 

 perhaps miles away to an electro-dynamic machine or 

 motor, where its retransformation into mechanical 

 power occurs, and it is set at the work of driving a mill 

 or other collection of mechanisms. A telephone sys- 

 tem illustrates in another way similar transformations 

 and retransformations of mechanical and electric energy, 

 and Mr. Hammer has thus produced a system involving 

 many transformations and including a circuit of a hun- 

 dred miles. 



Nature herself has in these cases usually already per- 

 formed some such transformations of energy in the 

 reduction of that so collected and applied to the form 

 in which the mechanic and the engineer finds it ready 

 to his hand. The water has been raised from the lakes 

 and the sea, and distributed by the clouds to the elevated 

 sources from which it flows downward in the streams ; 

 the winds are the result of differences of temperature 

 and the action of heat energy ; the heat of combustion 

 is the representative of an earlier form of energy in 

 which the heat of the sun and of the still coohng earth, 

 and the formation of the coal deposits in early geo- 

 logical periods, played a part. In a general way it has 

 come to be seen that every display of energy, like every 

 new form of matter, is the result of change in some 

 antecedent form, and that neither matter nor energy 

 can be destroyed. This has been admitted from the 

 time of Lavoisier, so far as it affects matter ; it has 



