Eleeclro -magnetic Experiments. 405 



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 Mas 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 ; whei the aeid was removed 

 from the zinc, the magnet continued to support, for a lV\v minutes, 



130 lbs. 



Exp. 13. With six wires, the weight supported was 570 lbs.; in all 

 these experiments, the wires were soldered to the galvamc clement; 

 the connexion, in no instance, was formed with mercury. 



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

 maximum weight lifted was 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. 



formed with a plate of 



long and 6 wide, and svrrounded by copper, was substituted fur the 

 galvamc element used in the last experiment; the weight lifted i* 

 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 live 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 bv 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. 



ascertain the effect of 



inch square, wa 



rf iron, a pair of plate s, exactly 

 ill the, wires: the weight lifted 



85 



The following experiments were made with wires of different 

 lengths, on the same horse-shoe. 



Vol. XIX.— No. 2. 52 



