128 



These natural motive principles are not always directly employed 

 in producing work, but are sometimes used to develope other power, 

 by disturbing the natural equilibrium of other forces, and in this way, 

 they give rise to a class of mechanical movers, which may be called 

 intermediate powers. It will be evident on a little reflection, that 

 the forces of gravity, cohesion, and chemical attraction, with those of 

 the imponderable agents of nature, so far as they belong to the earth, 

 all tend to produce a state of stable or permanent equilibrium at the 

 surface of our planet, — that in all cases, before the energies of these 

 torces can be exhibited, the disturbing effect of some extraneous force 

 is required, — hence these principles in themselves are not the primary 

 sources of power, but are merely secondary agents in producing me- 

 chanical effects ; — or, in other words, it will be found, that while the 

 approximate source of every power is the force exerted by matter, in 

 its passage from an unstable to a stable state of equilibrium, yet, in 

 all cases, it may be referred beyond this to a force which disturbed a 

 previously existing quiescence. As an example, we may take the 

 case of water power, in which the mechanical effects are approxi- 

 mately due to the return of the water to a state of stable equilibrium 

 on the surface of the ocean; but the cause of the continued motion 

 is the force which produced the original disturbance, and which ele- 

 vates the liquid in the form of vapour. Also, in the phenomena of 

 combustion, the immediate source of the power, evolved in the form 

 of heat, is the passage from an unstable state into one of stable com- 

 bination of the carbon and hydrogen of the fuel, and the oxygen of 

 the atmosphere; but this power may ultimately be resolved into the 

 force which caused the separation of these elements from their pre- 

 vious combination in the state of carbonic acid and water. 



Now the only forces of any importance, which operate at the sur- 

 face of the earth to counteract the tendency to a general state of 

 stable equilibrium are those derived from two sources, namely, celes- 

 tial disturbance, and what is called vital action; and hence all me- 

 chanical power, as well as all activity on the surface of the globe, 

 may be referred to these two sources. The only exception to this ge- 

 neral regulation is the comparatively limited effect of volcanic action, 

 which is a power, from whatever source it may be derived, that must 

 tend to exhaust itself. 



Thus far the author considered his conclusions founded on well 

 established physical laws; and perhaps here the true spirit of in- 

 ductive philosophy would admonish him to stop : but they who are 

 disposed to continue the speculation, and to consider the results of 



