310 WRITINGS OP JOSEPH HENRY. [1855- 



are sometimes known by the more scholastic names of 

 analysis and synthesis. The first method may perhaps be 

 considered the more rigid, and where a systematic treatise 

 on a subject is intended, and ample space allowed for its full 

 discussion it might be preferred; but where the object is to 

 give the greatest amount of information in the shortest time, 

 to put the reader in possession of the means through which 

 by his own reflection he can deduce from a single principle 

 hundreds of phenomena, and declare — prior to experiment 

 or observation, what will take place under given conditions, 

 the latter method will be the proper one to be adopted. 



It is impossible however to state a principle of very gene- 

 ral application without employing an hypothesis or an as- 

 sumption which though founded on strict analogy may 

 possibly not be absolutely true. We adopt such an hypoth- 

 esis temporarily, not as expressing an actual entity, but as 

 a provisional truth which may be modified or even aban- 

 doned when we find it no longer capable of expressing all 

 the phenomena. All we assert positively in regard to such 

 an hypothesis is that the phenomena to which it relates and 

 with which we are acquainted at the time exhibit themselves 

 as if it were true. 



When an assumed hypothesis of this kind furnishes an 

 exact expression of a large number of phenomena, and 

 enables us beforehand to calculate the time and form of their 

 occurrence,itis then called a theory. Tlie two terms — hypoth- 

 esis and theory — though in a strict scientific sense of very 

 different signification, are however often confounded and 

 otherwise mis-applied. Theory, in common language, is fre- 

 quently used in contradistinction to fact, and sometimes 

 employed to express unscientific and indefinite speculations. 

 The cause of truth would be subserved if these terms were 

 used in a more definite and less general sense; for example, 

 if the term speculation were restricted to those products of the 

 imagination which may or may not have an existence in 

 nature; the term hypothesis to suppositions founded on anal- 

 ogy and which serve to give more definite conceptions of 

 laws; while the ievvn. theory is reserved for generalizations 



