JOSEPH HENRY, LL.D. 285 



the ' quantity ' magnet, the other surrounded with 

 a continuous coil of very great length, designated 

 by him the { intensity ' magnet. . . . Never should 

 it be forgotten that he who first exalted the ' quan- 

 tity ' magnet of Sturgeon from a power of twenty 

 pounds to a power of twenty hundred pounds was 

 the absolute CREATOR of the ' intensity ' magnet ; 

 and that the principles involved in this creation 

 constitute the indispensable basis of every form of 

 the electro-magnetic telegraph since invented." 



Professor Silliman of Yale College said: "Henry 

 has the honor of having constructed by far the most 

 powerful magnets that have ever been known ; and 

 his last, weighing (armature and all) but 82^ 

 pounds, sustains over a ton; which is eight times 

 more powerful than any magnet hitherto known in 

 Europe." 



"In 1831," says Professor Henry, "I arranged 

 around one of the upper rooms of the Albany 

 Academy a wire of more than a mile in length, 

 through which I was enabled to make signals by 

 sounding a bell. The mechanical arrangement for 

 effecting this object was simply a steel bar, perma- 

 nently magnetized, of about ten inches in length, 

 supported on a pivot, and placed with its north end 

 between the two arms of a horse-shoe magnet. 

 When the latter was excited by the current, the 

 end of the bar thus placed was attracted by one 

 arm of the horse-shoe and repelled by the other, 

 and was thus caused to move in a horizontal plane 

 and its further end to strike a bell suitably ad- 



