ANIMAL MECHANISM: 



TERRESTRIAL AND AERIAL LOCOMOTION. 



INTRODUCTION. 



LIVING beings have been frequently and in every age 

 compared to machines, but it is only in the present day 

 that the bearing and the justice of this comparison are fully 

 comprehensible. 



No doubt, the physiologists of old discerned levers, pulleys, 

 cordage, pumps, and valves in the animal organism, as in the 

 machine. The working of all this machinei-y is called Animal 

 Mechanics in a great number of standard treatises. But these 

 passive organs have need of a motor ; it is life, it was said, 

 which set all these mechanisms going, and it was believed 

 that thus there was authoritatively established an inviolable 

 barrier between inanimate and animate machines. 



In our time it is at least necessary to seek another basis 

 for such distinctions, because modern engineers have created 

 machines which are much more legitimately to be compared 

 to animated motors ; which, in fact, by means of a little com- 

 bustible matter which they consume, supply the force requisite 

 to animate a series of organs, and to make them execute the 

 most various operations. 



The comparison of animals with machines is not only legiti- 

 mate, it is also extremely useful from different points of view. 

 It furnishes a valuable means of making the mechanical 

 phenomena which occur in living beings understood, by 

 placing them beside the similar but less generally known 

 phenomena, which are evident in the action of ordinary 



