320 WRITINGS OF JOSEPH HENRY. [1853 



before known or but partially understood; while the term 

 invention indicates the application of this knowledge, either 

 simply or in combination with other knowledge, to some 

 useful purpose in the arts. For example, Franklin discovered 

 the principle of electrical induction, or the action at a dis- 

 tance of a charged body on a conductor, and on this founded 

 his invention of the lightning-rod. 



It sometimes happens that the peculiar characteristic of 

 mi id and training necessary to the successful prosecution of 

 thuiO two branches of labor are found combined in the same 

 individual. Of a happy combination of this kind James 

 Watt affords a striking example, the like of which will be- 

 come more common in proportion as the means of intellectual 

 improvement afforded to workmen are extended. Generally 

 however the two faculties exist in the greatest degree of de- 

 velopment in separate individuals. The successful investi- 

 gation of a new principle in science generally requires much 

 previous study and preparation and a logical training, which 

 few men — however vigorous may be their native intellect, can 

 dispense with, and to acquire which the opportunities of the 

 workmen are inadequate. On the other hand the successful 

 introduction to common use of an invention requires a con- 

 test with the world from which the sensitive student of ab- 

 stract science shrinks with repugnance. I consider these 

 remarks of some importance, because in this country, where 

 there is so great a demand for immediate practical results, 

 the value of labor in the line of abstract science is not prop- 

 erly appreciated or encouraged. 



We have said that every age of the world has bequeathed 

 something of value to that which followed, and we may add 

 that it is doubtful whether any great truth has ever been 

 lost: though some may have apparently lain dormant for a 

 time, yet they have continually produced results. Some arts 

 have undoubtedly fallen into disuse, because they are no 

 longer required, or because they have been superseded by 

 more perfect processes. We however think it can be clearly 

 established that modern science is capable of re-producing 

 every invention of ancient art, and at an indefinite economy 

 of human time and human labor. 



