358 JOSEPH HENRY. 



respond, and Henry returned to the Albany Academy as assistant 

 teacher, and in 1828 as Professor of Mathematics. 



Only a few years had elapsed since the science of electricity had 

 taken a new departure under the name of electro-magnetism. Oersted, 

 of Copenhagen, had kindled the flame, which passed rapidly from hand 

 to hand among the scientific workers of Europe, until it culminated in 

 the splendid generalization of Ampere. This western continent may 

 have been tardy in welcoming the bright light in the east, but the 

 response, when given, was not a fire, but a conflagration. Professor 

 Henry led in the new line of physical research with a self-born 

 enthusiasm which seven hours of daily teaching in mathematics could 

 not extinguish or cool. The limits of this notice forbid a lengthened 

 statement of his contributions to electro-magnetism. But the fertile 

 principle which he deduced from his experiments must not be passed 

 over in silence. His distinction between quantity and intensity magnets, 

 and between quantity and intensity batteries (though now differently 

 expressed), is all-important and of manifold applications. Every 

 experiment with electro-magnetism, in the laboratory, in the lecture- 

 room, and in the arts, is a success or a failure in proportion as this law 

 is obeyed or ignored. If this discovery has linked Professor Henry's 

 name with the telegraph especially, it is because that was the great 

 problem of the hour, — unsolved, and as some supposed unsolvable. 

 It is not easy to draw the dividing line between the merits of the dis- 

 coverer and the inventor, when one follows closely upon the heels of 

 the other. Professor Henry's contribution to the final triumph was 

 large, and brilliant, and indispensable; but it was not all-sufficient. An 

 alphabet was wanting ; a sustaining battery must be invented ; more- 

 over, a man must appear with a capacity for business and a courage 

 born of hope, with no original knowledge of the familiar laws of elec- 

 tricity but with an easy absorption of the science of other men, who, 

 by a happy combination of experimental devices and the devotion of 

 years, might finally achieve a grand commercial success. In view of 

 Professor Henry's additional conquests in the realm of physical 

 research, science will ever rejoice that he was not himself dazzled by 

 the inviting prospect of riches and popular applause; that he re- 

 nounced the fruits of invention when they were almost within his 

 grasp ; that he preferred to any short-lived, meteoric display the chance 

 of shining for ever as a star in the upper heavens, with Agassiz, 

 Cuvier, and Faraday. 



Loyalty to the devotees of scientific research does not demand any 

 disparagement of the usefulness or the genius of inventors. If the 



