312 Experiments upon the Induction of Metallic Coils. 



the covering, and which obliquity in the contiguous layers was in an 

 opposite direction. As the ribbon was one inch in width and the 

 iron one inch in diameter, the angle at which the layers crossed each 

 other was more than 45°. 



4. The whole horse shoe was then wound with the same ribbon 

 singly, and that which was left after covering it was then coiled spi- 

 rally upon one extremity of the iron. A strong magnetic action was 

 now developed in the iron, much superior to that shown in any of 

 the preceding experiments. The pole supporting the spiral coil was 

 much superior in power to the other. 



5. The iron horse shoe was then covered with one hundred and 

 thirty feet of the same ribbon. This was wound singly over the 

 whole iron, and a spiral coiled around each pole, the two spirals be- 

 ing coiled in different directions, and one containing about twenty 

 five feet more than the other. This arrangement shewed consider- 

 able magnetic power, but not quite as much as the last. The two 

 coils being wound in different directions, nearly neutralize each 

 other, and the only power gained is that produced by the excess in 

 the length of one coil over the other. 



6. The same ribbon used in the last experiment, was coiled in 

 two spirals, one around each pole of about equal size and wound in 

 the same direction, and having the extremities of the ribbon in the 

 center of each coil respectively. This produced the most powerful 

 effect yet experienced, as the apparatus with the small battery of 

 eighteen inches and very feebly charged was capable of raising fifty 

 pounds. 



7. The whole apparatus was disposed as in the last experiment, 

 only that the extremities of the ribbon in one coil proceeded from 

 the center, and in the other from the circumference. This produ- 

 ced the most powerful effect of all and with the same battery raised 

 nearly twice the same weight. 



8. If the whole apparatus be arranged as in the last experiment, 

 and another coil be placed upon the extremities of the iron, taking 

 care that the current run in the same direction in both coils, upon 

 connecting this with the same battery as the other coil, the power 

 of the magnet will be greatly increased. 



It must appear evident to every one that the power of these mag- 

 nets may be increased ad infinitum, by increasing the size of the horse 

 shoe of soft iron, by increasing the width and length of the metallic 

 ribbons, and also increasing the power of the battery. The effect 



