REMINISCENCES BY PROF. H. C.CAMERON. 173 



In the discovery of the mode of magnetizing soft iron at.a distance 

 by means of currents of galvanism, and in his invention of this little 

 machine, was not merely the possibility, but the fact of the electro- 

 magnetic telegraph. Whatever may be the judgment of the general 

 public, men of science and of education will never deny to Joseph 

 Henry his just meed of praise in connection with this subject. It 

 must ever be remembered that he always placed discovery above 

 invention, and thought more highly of the principles of science than 

 of their practical application. 



Some of his discoveries came upon him suddenly, although he 

 never pursued any other than the inductive method, questioning 

 facts, and obtaining principles as results. Upon one occasion in 

 Albany, he was seated in the room with his family, and engaged in 

 profound thought. Suddenly he brought his hand down with force 

 upon the table by which he was sitting, and like Archimedes 

 when he discovered the mode of ascertaining the specific gravity of 

 bodies and cried out opr t xa^ eupyxa^ he exclaimed, "I have it," "I 

 have it." He had solved the problem on which he had been 

 engaged, and discovered an important principle of science. In 

 1844 the College Commencement was changed from the Fall to the 

 Summer, and the vacation lasted only two weeks. He spent these 

 two weeks in scientific experiments. And in what do you suppose 

 these experiments consisted ? The answer will excite a smile. In 

 blowing soap-bubbles. And yet from this childish amusement the 

 philosopher, like the great Newton before him, was deriving im- 

 portant truths in physical science. All his old pupils will recall 

 how careful he was in explaining, and how rigid he was in insisting 

 upon the inductive method of scientific investigation. None of his 

 pupils was ever likely to confound a mere hypothesis with a theory, 

 as too many scientific men at present are prone to do. 



In going to Washington he remarked that he " sacrificed reputa- 

 tion to fame." He felt that he should become known throughout 

 the country simply as the Director of the Smithsonian Institution 

 and to some extent of the science of the country, but that he should 

 have little time for scientific investigation which would increase his 

 reputation. This remark was, alas! too true. At that time he 

 seemed to be upon the verge of most important discoveries ; he had 



