The Electrical Discoveries of Joseph Henry 



By H. S. OSBORNE and A. M. BOWLING 



AX historical research into the accomplishments of a great sci- 

 entist, such as Henry, includes two main parts. There is first 

 the proof, based upon the record, that he accomplished certain things. 

 This being an affirmative proof can be quite definite. There is a 

 second step, however, which is of interest in the appraisal of his work, 

 namely, showing in respect to what items he was first. This means in 

 effect proving that in respect to these items no one anticipated him. 

 Such an assertion, being a universal negative, cannot be absolutely 

 proved, but can, of course, by sufficient work be shown to be probable 

 in a high degree. 



The student of Joseph Henry's work is hampered in the number of 

 items which can be included in the affirmative proof by the fact that no 

 adequate record has been preserved. Henry was slow and fragmen- 

 tary in publication and most of his personal records were destroyed in a 

 fire at the Smithsonian Institution in 1865. While his publications 

 and the testimony of others who saw his experiments show a prodigious 

 accomplishment, it is probable that a more complete record would have 

 added other important contributions made by Henry to electrical 

 science, and in other fields of scientific work. 



When one attempts to appraise Henry's work in comparison with 

 that of his contempories, and particularly to determine in what cases 

 Henry's discoveries were prior to those of others, the difficulty is multi- 

 plied. There was a complete lack of means for rapid communication 

 one hundred years ago. As a result scattered scientists working in the 

 same field often independently made similar discoveries and the 

 scientific journals in which their results were published were neither 

 rapidly nor widely distributed. The result is illustrated by the fact 

 that so fundamental an advance as Ohm's law, published in full in 1827, 

 was little known or accepted even in Europe for a decade. 



The original notes of the scientific investigators are for the most part, 

 with the outstanding exception of Michael Faraday, not available, and 

 credit for priority of discovery has generally, by common consent, been 

 associated with priority of publication. Even at the time there were 

 some interesting cases in Europe where conflicting claims of priority 

 were made and the implication is made in some cases that the scientific 



1 



