ji8 THE POPULAR SCIENCE MONTHLY. 



bhed dynamical laws. By that common observation -which precedes 

 the more exact observations of science, we are taught tbat all the frag- 

 ments, having risen to heights more or less various, will fall ; that they 

 will reach the ground at scattered places within a circumscribed area 

 and at somewhat different times. Science enables us to say more than 

 'his. From those same principles whence are inferable the path of a 

 planet or a projectile, it deduces the truth that each fragment will de- 

 scribe a curve ; that all the curves, though individually different, will 

 he specifically alike ; that (ignoring deviations caused by atmospheric 

 resistance) they will severally he portions of ellipses so eccentric as to 

 be indistinguishable from parabolas such parts of them, at least, as 

 are described after the rush of gases ceases further to accelerate the 

 fragments. But, while the principles of Mechanics help us to these cer- 

 tainties, we cannot learn from them any thing more definite respecting 

 the courses that will be taken by particular fragments. Whether, of 

 the mass overlying the powder to he exploded, the part on the left will 

 be propelled upward in one fragment or several ? whether this piece 

 will be shot higher than that ? whether any, and, if so, which of the 

 projected masses will be stopped in their courses by adjacent objects 

 they strike ? are questions it cannot answer. Not that there will be 

 any icant of conformity to law in these results, but that the data, on 

 which predictions of them are to be based, cannot be obtained. 



Observe, then, that, respecting a concrete phenomenon of some com. 

 plexity, the most exact science enables us to make predictions that are 

 mainly general, or only partially special. Seeing that this is so, even 

 where the causes and effects are not greatly involved, and where the 

 science of them is well developed, much more may we expect it to be 

 so among the most involved causes and effects, the science of which is 

 but rudimentary. This contrast, between the generalities that admit 

 of prevision and the specialties that do not admit of prevision, will be 

 still more clearly seen on passing from this preliminary illustration to 

 an illustration in which the analogy is closer. 



What can we say about the future of this newly-born child ? Will 

 it die of some disorder during infancy ? Will it survive awhile, and 

 be carried off by scarlet fever or whooping-cough ? Will it have 

 measles or small-pox, and succumb to one or the other ? None of 

 these questions can be answered. Will it some day fall down-stairs, 

 or be run over, or set fire to its clothes ; and be killed or maimed by 

 one or other of these accidents ? These questions also have no an- 

 swers. None can tell whether in boyhood there may come epilepsy, 

 or St. Vitus's dance, or other formidable affection. Looking at the 

 child now in the nurse's arms, none can foresee with certainty that it 

 will be stupid or intelligent, tractable or perverse. Equally beyond 

 possibility of prediction are those events which, if it survives, will 

 occur to it in maturity partly caused by its own nature, and partly 



