338 



INDUCTION. 



cause and effect. We presume the 

 contrary j we expect to find that the 

 whole series originates either from 

 the continued action of fixed causes, 

 or from causes which go through a 

 corresponding process of continuous 

 change. A tree grows from half an 

 inch high to a hundred feet, and some 

 trees will generally grow to that 

 height unless prevented by some coun- 

 teracting cause. But we do not call 

 the seedling the cause of the full- 

 grown tree ; the invariable antece- 

 dent it certainly is, and we know 

 very imperfectly on what other ante- 

 cedents the sequence is contingent, 

 but we are convinced that it is con- 

 tingent on something, because the 

 homogeneousness of the antecedent 

 with the consequent, the close re- 

 semblance of the seedling to the tree 

 in all respects except magnitude, and 

 the graduality of the growth, so ex- 

 actly resembling the progressively 

 accumulating effect produced by the 

 long action of some one cause, leave 

 no possibility of doubting that the 

 seedling and the tree are two terms 

 in a series of that description, the 

 first term of which is yet to seek. 

 The conclusion is further confirmed 

 by this, that we are able to prove by 

 strict induction the dependence of 

 the growth of the tree, and even of 

 the continuance of its existence, upon 

 the continued repetition of certain 

 processes of nutrition, the rise of the 

 sap, the absorptions and exhalations 

 by the leaves, &c. ; and the same ex- 

 periments would probably prove to 

 us that the growth of the tree is the 

 accumulated sum of the effects of 

 these continued processes, were we not, 

 for want of sufficiently microscopic 

 eyes, unable to observe correctly and 

 in detail what those effects are. 



This supposition by no means re- 

 quires that the effect should not, 

 during its progress, undergo many 

 modifications besides those of quan- 

 tity, or that it should not sometimes 

 appear to undergo a very marked 

 change of character. This may be 

 •ither because the unknown cause 



consists of several component ele- 

 ments or agents, whose effects, accu- 

 mulating according to different laws, 

 are compounded in different propor- 

 tions at different periods in the ex- 

 istence of the organised being ; or 

 because, at certain points in its pro- 

 gress, fresh causes or agencies come 

 in, or are evolved, which intermix 

 their laws with those of the orime 

 agent. 



CHAPTER XVI. 



OP EMPIRICAL LAWS. 



§ I. Scientific inquirers give the 

 name of Empirical Laws to those uni- 

 formities which observation or experi- 

 ment has shown to exist, but on which 

 they hesitate to rely in cases varying 

 much from those which have been 

 actually observed, for want of seeing 

 any reason wAy such a law should exist. 

 It is implied, therefore, in the notion 

 of an empirical law, that it is not an 

 ultimate law ; that if true at all, its 

 truth is capable of being, and requires 

 to be accounted for. It is a derivative 

 law, the derivation of which is not yet 

 known. To state the explanation, the 

 ichyy of the empirical law, would be to 

 state the laws from which it is de- 

 rived ; the ultimate causes on which 

 it is contingent. And if we knew 

 these, we should also know what are 

 its limits — under what conditions it 

 would cease to be fulfilled. 



The periodical return of eclipses, 

 as originally ascertained by the per- 

 severing observation of the early 

 Eastern astronomers, was an empiri- 

 cal law until the general laws of the 

 celestial motions had accounted for it. 

 The following are empirical laws still 

 waiting to be resolved into the simpler 

 laws from which they are derived. 

 The local laws of the flux and reflux 

 of the tides in different places : the 

 succession of certain kinds of weather 

 to certain appearances of sky : the 

 apparent exceptions to the almost uni- 

 versal truth that bodies expand by 

 increase of temperature ; the law that 



