The Multiplication of Effects §156. To the cause of increasing complexity set forth in the lastchapter, we have in this chapter to add another. Though secondary in orderof time, it is scarcely secondary in order of importance. Even in the absenceof the cause already assigned, it would necessitate a change from the homogeneousto the heterogeneous; and joined with it, it makes this change both morerapid and more involved. To come in sight of it we have but to pursue a stepfurther that conflict between force and matter already delineated. Let usdo this.
As already shown, when the components of a uniform aggregate are subjectto a uniform force, they being differently conditioned, are differently modified.
But while we have contemplated the various parts of the aggregate as undergoingunlike changes, we have not yet contemplated the unlike changes simultaneouslyproduced on the various parts of the incident force. These must be as numerousas the others. In differentiating the parts on which it falls in unlike ways,the incident force must itself be correspondingly differentiated. Insteadof being as before, a uniform force, it must thereafter be a multiform force-- a group of dissimilar forces. A few illustrations will make this truthmanifest.
In the case, lately cited, of a body shattered by violent collision, besidesthe change of the homogeneous mass into a heterogeneous group of scatteredfragments, there is a change of the homogeneous momentum into a group ofmomenta, heterogeneous in both amounts and directions. Similarly with theforces we know as light and heat. After the dispersion of these by a radiatingbody towards all points, they are re-dispersed towards all points by thebodies on which they fall. Of the Sun's rays, issuing from him on every side,some few strike the Moon. Reflected at all angles from the Moon's surface,some few of these strike the Earth. By a like process the few which reachthe Earth are again diffused: some into space, some from object to object.
And on each occasion, such portions of the rays as are transmitted insteadof reflected, undergo refractions or other changes which equally destroytheir uniformity. More than this is true. By conflict with matter a uniformforce is in part changed into forces differing in their kinds. When one bodyis struck against another, that which we usually regard as the effect, isa change of position or motion in one or both bodies. But this is a veryincomplete view of the matter. Besides the visible mechanical result, soundis produced -- a vibration in one or both bodies and in the surrounding air;and under some circumstances we call this the effect. Moreover, the air hasnot simply been made to vibrate; it has had currents raised in it by thetransit of the bodies. Further, if there is not that great structural changewhich we call fracture, there is a disarrangement of the particles of thetwo bodies around their point of collision; amounting in some cases to avisible condensation. Yet more, this condensation is accompanied by genesisof heat. In some cases a spark -- that is, light -- results from the incandescenceof a portion struck off. Thus by the original mechanical force expended inthe collision, at least five kinds of forces have been produced. Take, again,the lighting of a candle. Primarily, this is a chemical change consequenton a rise of temperature. The process of combination having once been setgoing by extraneous heat, there is a continued formation of carbon dioxide,water, etc. Along with this process of combination there is a productionof heat; there is a production of light; there is an attending column ofhot gases generated; there are currents caused in the surrounding air. Nordoes the decomposition of one force into many forces end here. Each of theseveral changes worked becomes the parent of further changes. The carbondioxide formed will eventually combine with some base; or under the influenceof sunshine give up its carbon to the leaf of a plant. The water will modifythe hygrometric state of the air around; or, if the current of hot gasescontaining it comes against a cold body, will be condensed: altering thetemperature, and perhaps the chemical state, of the surface it covers. Theheat given out melts the subjacent tallow and expands whatever else it warms.
The light, falling on various substances, calls forth from them reactionsby which it is decomposed, and divers colours are thus produced. Similarlywith these secondary actions, which may be traced out into ever-multiplyingramifications, until they become too minute to be appreciated. Universally,then, the effect is more complex than the cause. Whether the aggregate onwhich it falls be homogeneous or otherwise, an incident force is transformedby the conflict into a number of forces that differ in their amounts, ordirections, or kinds; or in all these respects. And of this group of variously-modifiedforces, each ultimately undergoes a like transformation.
