The Electrical Discoveries of Joseph Henry, A Supplement to The Bell System Technical Journal, July 1932

H. S. OSBORNE AND A. M. D O W L I N G AMERICAN TELEPHONE NEW AND TELEGRAPH U. S. A. COMPANY YORK, oyf Supplement to The *Bell System July, Technical Journal 1932 The Electrical Discoveries of Joseph Henry B y H . s . O S B O R N E and A . M . DOWLING- A N historical research into the accomplishments of a great scientist, 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 c^n 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 fragmentary 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 multiplied.