Page:Popular Science Monthly Volume 13.djvu/379

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IN the death of Prof. Henry, Secretary of the Smithsonian Institution, which occurred May 13th, American science has met with an irreparable loss. Little needs to be said in eulogy of a character so widely and familiarly known, and so profoundly respected and admired, as this venerable savant. In Volume II. of The Popular Science Monthly will be found an excellent portrait of Prof. Henry, with a sketch of his life, and an enumeration of his most important scientific labors; but there are two or three features of his career that are entitled to special recognition, now that he has passed away.

It is very well understood in the scientific world that, more than any other man, Prof. Joseph Henry is the scientific founder of the system of modern telegraphy, and this honor ought to be equally conceded to him by the general public. His earliest discoveries and his most important scientific work were in the field of electro-magnetic research, entered upon within a very few years after Oersted had announced the discovery of the relations of electricity and magnetism. Prof. Henry worked out experimentally, and by the most elaborate investigations, those laws and principles of electro-magnetic action which made the telegraph possible; and not only this, but he actually constructed and operated an electric telegraph years before Prof. Morse turned his attention to the subject. The great contrivance was of course bound to come, but no consideration of this kind should be permitted to detract in the slightest degree from the honor of those by whom it came. The scientific discoverer is entitled at any rate to have his work recognized, especially as he rarely gets anything else. It is the man who runs in upon his discoveries and applies them and brings them into notice that is usually credited in the popular estimation with all the honor. In this case, Morse has appropriated the glory that fairly belongs to Henry. Morse originated nothing by the current telegraphic alphabet—that is, the combinations of taps and clicks of the instrument, by which letters are denoted. Electricity had long been looked to as an agent for the transmission of intelligence. Many experiments had been made from the time of Franklin to secure this object, but none of them had succeeded. Various contrivances had met more recently with partial success, but Prof. Henry's sounder of 1830 has gradually displaced, and has now almost entirely superseded, all other methods of electric signaling. Mr. E. N. Dickerson, in tracing out the history of telegraphic invention, after stating the merits of various previous contrivances, thus refers to Henry's work:

"Then came Prof. Henry, who, in 1830, deduced from the hypothesis of Ampère—that magnetism was the circulation of electricity at right angles to the line connecting the poles of the magnet—the invention now known as the compound electro-magnet. In that year he constructed an electro-magnet that would sustain 1,000 pounds weight; and he answered the demonstration of Barlow, and proved that the electro-magnetic telegraph was possible. In the same year he set up an electro-magnetic telegraph at Albany, over a line of a mile and a half in length, using what is now known as the 'polarized relay,' between the poles of which a magnetic armature vibrated upon a hinge, as the current of electricity was reversed—the end of the armature striking a sounder, and transmitting the intelligence by sound. This was the first electro-magnetic telegraph (I use the popular phrase) ever made; and it was the first one possible