ISO! 



PHYSICS DURING THE LAST CENTURY.* 

 Francis E. Nipher. 



The study of physical science had its origin among people 

 who had been accustomed to reach most of the results which 

 seemed to them of value, by processes of a purely mental 

 character. After the result had been attained it was consid- 

 ered important that it should be accepted by others. It was 

 regarded as a duty for every man to convert others to his 

 philosophy. It was considered of importance if some record 

 of a predecessor could be found and quoted, showing that the 

 new result was in line with precedents. It is difficult for us in 

 this day to realize the endless quarreling, and irrelevant or 

 senseless debating which attended the early advances in every 

 branch of science. It is one of the greatest advances in 

 science that we no longer consider it of importance that our 

 thinking should square itself with the ideas of those who have 

 preceded us in a former age, and who perhaps did not and 

 could not think seriously about the matter at all. It is cer- 

 tainly an advance of a very fundamental and far-reaching 

 character, that our explanation of the working of a pump 

 does not involve the proposition that " Nature abhors a 

 vacuum." It is hard for us to understand how men of a 

 former time could have felt any mental stimulation in the 

 doctrine that the number of planets could not exceed the 

 number of openings in the head of a man, or that anything 

 could be proved by an astonishing illustration of something 

 else. 



In the century which preceded the last there were men who 

 began to have what we should call a sense of logical connec- 

 tion in physical reasoning. In the preface to Rohault's Na- 

 tural Philosophy, the English edition of which appeared in 

 1729, are some keen and discriminating comments upon what 



* Address delivered before The Academy of Science of St. Louis, Octo- 

 ber 21, 1901. 



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