THE MULTIPLICATION OF EFFECTS. 447 



aggregation, must have become gradually divided into dif- 

 ferent forces: and that each further stage of complication 

 in the resulting aggregate, must have initiated further sub- 

 divisions of this force — a further multiplication of effects, 

 increasing the previous heterogeneity. 



This section of the argument may however be adequate- 

 ly sustained, without having recourse to any such hypotheti- 

 cal illustrations as the foregoing. The astronomical attri- 

 butes of the Earth, will even alone suffice our purpose. 

 Consider first the effects of its momentum round its axis. 

 There is the oblateness of its form; there is the alternation 

 of day and night; there are certain constant marine cur- 

 rents; and there are certain constant aerial currents. Con- 

 sider next the secondary series of consequences due to the 

 divergence of the Earth's plane of rotation from the plane 

 of its orbit. The many differences of the seasons, both 

 simultaneous and successive, which pervade its surface, are 

 thus caused. External attraction acting on this rotating 

 oblate spheroid with inclined axis, produces the motion 

 called nutation, and that slower and larger one from which 

 follows the precession of the equinoxes, with its several se- 

 quences. And then by this same force are generated the 

 tides, aqueous and atmospheric. 



Perhaps, however, the simplest way of showing the mul- 

 tiplication of effects among phenomena of this order, will be 

 to set down the influences of any member of the Solar Sys- 

 tem on the rest. A planet directly produces in neighbour- 

 ing planets certain appreciable perturbations, complicating 

 those otherwise produced in them ; and in the remoter plan- 

 ets it directly produces certain less visible perturbations. 

 Here is a first series of effects. But each of the perturbed 

 planets is itself a source of perturbations — each directly 

 affects all the others. Hence, planet A having drawn planet 

 B out of the position it would have occupied in A's absence, 

 the perturbations which B causes are different from what 

 they would else have been ; and similarly with C, D, E, &c. 



