228 MEMORIAL OF JOSEPH HENRY. 



magnetic telegraph since invented. They settled satisfactorily (in 

 Barlow's phrase) the "only question wliich could render the result 

 doubtful;" and though derived from the magnet, were obviously 

 as applicable to the galvanometer needle.* Professor Moll, the 

 foremost of Europeans in the electro-magnetic chase, and close 

 upon the heels of Henry in one portion of his researches, pro- 

 duced a powerful "quantity" magnet, but one hopelessly and radi- 

 cally incapacitated from any such application. 



It is idle to say in disparagement of these successes, that in the 

 competitive race of numerous distinguished investigators in the field, 

 diligently searching into the conditions of the new-found agency, 

 the same results would sooner or later have been reached by others. 

 For of what discovery or invention may not the same be said ? 

 Only those who have sought in the twilight of uncertainty, can 

 appreciate the vast economy of effort by prompt directions to the 

 path from one who has gained an advance. Not for what might l^e, 

 but for the actual bestowal, does he who first grasps a valuable truth 

 merit the return of at least a grateful recognition. 



If these results apparently so simple when announced by Henry, 

 have never been justly appreciated either at home or abroad, no 

 such complaint ever escaped their author. No such thought seems 

 ever to have occurred to his artless nature. For him the one suffi- 

 cient incentive and recompense was the advancement of himself and 

 others in the knowledge of nature's laws. With the telegraph con- 

 sciously within his grasp, he was well content to leave to others the 

 glory and the emoluments of its realization. 



At the beginning of the year 1831, Henry had suspended around 

 the walls of one of the upper roorfis in the Albany Academy, a mile 

 of copper bell-wire interposed in a circuit between a small Cruick- 

 shanks battery and an "intensity" magnet of continuous fine coil. A 

 narrow steel rod (a permanent magnet) pivoted to swing horizontally 

 like the compass needle, was arranged so that one end remained in 



*"For circuits of small resistance, galvanometers of small resistance must bo 

 used. For circuits of large resistance, galvanometers of large resistance must also 

 be used; not that their resistance is any advantage, but becjiuse we cannot have a 

 galvanometer adapted to indicate very small currents without having a very large 

 number of turns in the coil, and this involves necessarily a large resistance." 

 Professor F. Jenkin, Electricity and Magnetism, 12mo. London, and New York, 1873. 

 chap. iv. sect. 8, p. 89. 



