L72 MEMORIAL OF JOSEPH HENRY. 



and it is a matter of the mosl profound regret that it was ever de- 

 molished. It corresponded in appearance 'with the building con- 

 taining the Geological lecture-room and the Philadelphian room-. 

 The main room was equal in si/e to the two rooms of the Philadel- 

 phian Society, and there was a smaller room in a projection in 1 1 n - 

 roar, which was subdivided into a room of moderate size, ami two 

 small ones. The apparatus was placed in glass cases surrounding 

 tlio main room, the Mats occupying the centre. Probably the most 

 interesting things in this room wore the little horse-shoe electro- 

 magnet, with which he made some of his most important discove- 

 rt the lit tlo machine which he invented, and which was the first 



machine moved by electro-magnetism, — and the large electro-magnet, 

 which could support 3,300 pounds, and which was for many years 

 the largest in the world. It could be magnetized, demagnetized, 

 and remagnetized so rapidly that a weight of hundreds of pounds 

 could not detach itself from the grasp of the magnet in the interval 

 of reversing the curn nts. These things are still preserved in the 

 Scientific School, along with the small glass cylinders, covered with 

 sealing-wax, and the electrical machine prepared after the directions 

 of Franklin. As an illustration of character it may lie men- 

 tioned that in the largest room of the projection hung a tradesman's 

 placard, upon which was depicted a folded whip, with the legend: 



"A PLACE FOE EVERYTHING, AM' EVERYTHING IX ITS l'l.Ai E." 



From his lecture-room to the opposite building, and thence to hi- 

 honse, which was the house now occupied by General Karee, lmt 

 then standing on the site of Re-Union Hall, stretched a wire, through 

 which current- of electricity were sent that rang bells and thus con- 

 veyed messages. In his house lie also had wire connected with the 

 lightning-rod, and needles inserted in the coils of it, that, like 

 Franklin, he might study the effects of electricity while the storms 

 were raging. The little machine mentioned was simply a small 

 beam of iron, surrounded by a conductor of insulated copper wire 

 and supported by a fulcrum, which was caused to oscillate by the 

 influence of two -mall stationary upright magnets near its ends. .V 

 maker of philosophical apparatus once visited Princeton to -ell 

 Professor Henry some of' his machine-. He showed the person 

 this little machine, and was threatened with a suit for "infringe- 

 ment of patent rights I " 



