SKETCH OF PROFESSOR HENRY. 743 



Prof. Henry was married in May, 1830, to Miss Alexander*, of 

 Schenectady, the sister of Prof. Alexander, of Princeton, and from the 

 ardent devotion of his wife, and the fraternal sympathy of her brother 

 in his pursuits, he has received assistance and support beyond that 

 which usually fall to the lot of men. The most peaceful, and to him- 

 self the most profitable, part of his life was that spent in Princeton, 

 for which place, and the college connected with it, he retains the 

 warmest attachment. 



The following is a brief enumeration of his scientific investigations 

 and discoveries : 



1. A sketch of the topography of the State of New York, embody- 

 ing the results of the survey before mentioned. 



2. In connection with Dr. Beck and the Hon. Simeon De Witt, the 

 organization of the meteorological system of the State of New York. 



3. The development, for the first time, of magnetic power, suffi-. 

 cient to sustain tons in weight, in soft iron, by a comparatively feeble 

 galvanic current. 



4. The first application of electro-magnetism as a power, to pro- 

 duce continued motion in a machine. 



5. An exposition of the method by which electro-magnetism might 

 be employed in transmitting power to a distance, and the demonstra- 

 tion of the practicability of an electro-magnetic telegraph, which, 

 without these discoveries, was impossible. 



6. The discovery of the induction of an electrical current in a long 

 wire upon itself, or the means of increasing the intensity of a current 

 by the use of a spiral conductor. 



V. The method of inducing a current of quantity from one of in- 

 tensity, and vice versa. 



8. The discovery of currents of induction of different orders, and 

 of the neutralization of the induction by the interposition of plates 

 of metal. 



The discovery that the discharge of a Leyden jar consists of a 

 series of oscillations backward and forward until equilibrium is re- 

 stored. 



10. The induction of a current of electricity from lightning at a 

 great distance, and proof that the discharge from a thunder-cloud also 

 consists of a series of oscillations. 



11. The oscillating condition of a lightning-rod while transmitting 

 a discharge of electricity from the clouds causing it, though in perfect 

 connection with the earth, to emit sparks of sufficient intensity to ig- 

 nite combustible substances. 



1 2. Investigations on molecular attraction, as exhibited in liquids, 

 and in yielding and rigid solids, and an exposition of the theory of 

 soap-bubbles. (These originated from his being called upon to inves- 

 tigate the causes of the bursting of the great gun on the United States 

 steamer Princeton.) 



