860 JOSEPH HENRY. 



In 1832, Professor Henry removed to Princeton to fill the chair of 

 Natural Philosophy in the College of New Jersey. Here he fouud 

 sympathizing associates, congenial duties, aud the opportunity for origi- 

 nal research. One year earlier Faraday, already widely known by 

 his chemical discoveries, appeared upon the field of experimental elec- 

 tricity, and immediately became the most conspicuous figure thereon, 

 the cynosure of admiring eyes in every land. His discovery of in- 

 duced currents, and of the evolution of electricity from magnets, 

 marked a new era in the science of electricity, elucidating facts 

 which had defied the ingenuity of Arago, Herschel, and Babbage, 

 creating the science of magneto-electricity as the correlative of 

 electro-magnetism, and justly claiming for its last-born the splendors 

 and wonders of the Ruhmkorff coil, the Gramme machine, and the tel- 

 ephone. Henry supplemented the work of Faraday by his own dis- 

 coveries of the ea^ra-current in the primitive circuit, and of induced 

 currents of higher orders in as many adjacent circuits, lie also 

 succeeded where Faraday had doubts about his own experiments; 

 viz. in obtaining unequivocal indications of similar induction in the 

 momentary passage of electricity of high tension ; proving also the 

 oscillating discharge of the Leyden jar. Numerous experiments were 

 made on induction by thunder-clouds, and on atmospheric electricity in 

 general, by means of tandem-kites and lightning-rods. 



Nobili and Melloni had widened and deepened the foundations of 

 thermotics, unveiling new and intimate analogies between radiant light 

 and heat, and enriching physical cabinets with many novelties, espe- 

 cially the thermopile and the galvanometer. Henry took advantage of 

 the new instruments for measuring the heat of different parts of the 

 sun. Seech i, the late astronomer and meteorologist of the Collegio 

 Romano, distinguished as the foster-brother of Victor Emmanuel, but 

 more as the gifted expounder of solar physics, owed his first inspiration 

 in science, in his youth (for he died in 1878, at the age of fifty-nine), 

 to Henry, whom he assisted in these experiments. Doubtless, other 

 young men, if they could be heard, would confess to an equal enthusi- 

 asm for science, caught from the same high example. But the multi- 

 tudinous productions which issued in rapid succession from the prolific 

 brain and pen of Secchi, without the adventitious reinforcement of 

 imaginary cases, justify and demand the assertion that what Henry led 

 others to do is second only in importance to what he did himself. 



More than fifty years ago, a little book was published under the 

 fascinating title of " Philosophy in Sport made Science in Earnest." 

 Of the many ingenious, complex, and costly instruments of research, 



