44 WRITINGS OF JOSEPH HENRY. [1831 



through all the series, the whole will form a continued coil 

 of one long wire. By soldering different ends, the whole 

 may be formed into a double coil of half the length, or into 

 a triple coil of one third the length, &c. The horse-shoe 

 was suspended in a strong rectangular wooden frame 3 feet 

 9 inches high and 20 inches wide, an iron bar was fixed 

 below the magnet so as to act as a lever of the second order; 

 the different weights supported, were estimated by a sliding 

 weight in the same manner as with a common steelyard. 

 (See the sketch of the magnet.) ^ 



In the experiments immediately following,* a small single 

 battery was used, consisting of two concentric copper cyl- 

 inders, with zinc between them ; the whole amount of zinc 

 surface exposed to the acid from both sides of the zinc was 

 f of a square foot ; the battery required only half a pint of 

 dilute acid for its submersion. 



Exp. 8. Each wire of the horse-shoe was soldered to the 

 battery in succession, one at a time ; the magnetism devel- 

 oped by each was just sufficient to support the weight of 

 the armature, weighing 7 lbs. 



Exp. 9. Two wires, one on each side of the arch of the 

 horse-shoe, were attached ; the weight lifted was 145 lbs. 



Exp. 10. With two wires, one from each extremity of the 

 legs, the weight lifted was 200 lbs. 



Exp. 11. With three wires, one from each extremity of the 

 legs, and the other from the middle of the arch, the weight 

 supported was 300 lbs. 



Exp. 12. With four wires, two from each extremity, the 

 weight lifted was 500 lbs. and the armature ; when the acid 

 was removed from the zinc, the magnet continued to sup- 

 port, for a few minutes, 130 lbs. 



Exp. 13. With six wires, the weight supported was 570 

 lbs.; in all these experiments, the wires were soldered to the 

 galvanic element; the connexion, in no instance, was formed 

 with mercury. 



Exp. 14. When all the wires, (nine in number,) were at- 

 tached, the maximum weight lifted was 650 lbs. and this aston- 



* All the weights in this series of experiments are avoirdupois. 



