740 THE POPULAR SCIENCE MONTHLY, 



nomena. But it can only advance where the otlier has already, in 

 some measure, opened up the region, i. e., given an inductive knowledge 

 of the laws, at least, for some groups of the phenomena belonging to 

 it, and the point is merely the testing and clearing up of the already- 

 found laws, the passage from them to the last and most general laws 

 of the region in question, and the complete unfolding of their conse- 

 quences. This other way leads to a rich knowledge of the behavior 

 of natural substances and forces, in which at first the law-element is 

 recognized only in the form in which artists perceive it, through vivid 

 sensuous contemplation of the type of its action, in order to a later 

 working out of it in the pure form of an idea. These two sides of the 

 physicist's work are never quite sej^arate from each other, though some- 

 times the diversity of individual gifts will adapt one man for mathe- 

 matical deduction, another for the inductive activity of experimenta- 

 tion. Should the first method, however, become w^holly divorced from 

 actual observations, it falls into the danger of laboriously building 

 castles in the air, on unstable foundations, and of not finding the points 

 at which it may verify the agreement of its deductions with fact. The 

 second, on the other hand, would lose sight of the proper aim of sci- 

 ence, if it did not work toward ultimately bringing its observations 

 into the precise form of the idea. 



The first discovery of laws of Xature previously unknown, that 

 is, of new forms of likeness in the course of apparently unconnected 

 phenomena, is a matter of sense (taking the word in its widest meaning), 

 and must nearly always be accomplished only by comparison of nu- 

 merous sensuous perceptions. The perfection and purification of that 

 which has been found fall afterward under the w^orking of the deduc- 

 tive method of thinking, and preferentially of mathematical analysis, 

 as the final question is ever about equality of quantities. 



INTow, Mr. Tyndall is par excellence an experimenter ; he forms his 

 generalizations from extensive observations of the play of natural 

 forces, and carries over what he has seen, in some cases to the great- 

 est, in others to the smallest relations of space (as appeared in the 

 lecture referred to). It is quite a mistake to consider what he calls 

 imagination as mere fancy [Phantasterei). It is exactly the opposite 

 that is meant — full sensuous contemplation. To this mode of work- 

 ing is evidently to be attributed the clearness of his lectures on phys- 

 ical phenomena, as also his success as a popular lecturer. 



