NOTICE BY PROF. J. LOVEEING. 429 



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

 < fersted, of ( 'openhagen, had kindled the flame, which passed rapidly 

 from hand to hand among the scientific workers <>t' Europe, until it 

 culminated in the splendid generalization of Ampere. This west- 

 ern continent may have been tardy in welcoming the bright light 

 in tin' east, but the response, when given, was nol a (ire, 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. lint the fertile principle which he deduced 

 fnun his experiments must not be passed over in silence. His dis- 

 tinction 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 merit- of the 

 discoverer and the inventor, when one follows closely upon the heels 

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

 was large, ami brilliant, and indispensable; but it was not all- 

 sufficient. An alphabet was wanting; a sustaining battery must be 

 invented; moreover, a man must appear with a capacity for busi- 

 ness and a courage born of hope, with no original knowledge of the 

 familiar laws of electricity 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 commer- 

 cial 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 renounced 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. 



