Eleectro-magnetic Experiments. 403 



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

 were attached ; the weight hfted 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 support, for a few minutes, 

 130 lbs. 



Exp. 13. With six wires, the weight supported was 5701bs. ; 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 attached, the 

 maximum weight lifted ^oas 650 lbs. and this astonishing result, it 

 must be remembered, was produced by a battery containing only | of 

 a square foot of zinc surface, and requiring only half a pint of diluted 

 acid for its submersion. 



Exp. 15. A small battery, formed with a plate of zinc 12 inches 

 long and 6 wide, and surrounded by copper, was substituted for the 

 galvanic element used in the last experiment; the weight lifted in 

 this case was 750 lbs. This is probably the maximum of magnetic 

 power which can be developed in this horse-shoe, as with a large ca- 

 lorimoter, containing 28 plates of copper and zinc, each 8 inches 

 square, the effect was not increased, and indeed we could not succeed 

 in making it lift as much as with the small battery. 



The strongest magnet of which we have any account, is that in the 

 possession of Mr. Peale, of Philadelphia ; this weighs 53 lbs. and lifted 

 310 lbs. or about six times its own weight. Our magnet weighs 21 

 lbs. and consequently lifts more than thirty five times its own weight; 

 it is probably, therefore, the most powerful magnet ever constructed. 



This, however, is by no means the maximum, which can be produ- 

 ced by a small galvanic element, as in every experiment we have made 

 the power increases by increasing the quantity of iron ; with a bar 

 similar to the one used in these experiments, but of double the diam- 

 eter, or of 8 times the weight, the power would doubtless be quadru- 

 ple, and that too without increasing the size of the galvanic element. 



Exp. 16. In order to ascertain the effect of a very small galvanic 

 element on this large quantity of iron, a pair of plates, exactly one 

 inch square, was attached to all the wires; the weight lifted was 

 85 lbs. 



The following experiments were made with wires of different 

 lengths, on the same horse-shoe. 



Vol. XIX.— No. 3. 52 



