19'k Mr. Rainey's Analysis ofDr, Ritchie's Reply, 



may notbe increased a third or a fourth, or even a tenth, if the 

 battei-y be a powerful one." — See Phil. Mag., January, p. b9>. 



From this experiment Dr. Ritchie not only endeavours to 

 convince every person of the absurdity of my views, but so 

 deeply is he impressed with the correctness of its indications 

 that conclusions are deduced from it even with arithmetical 

 precision. 



Dr. Ritchie must know that if a bar of iron be under the 

 influence of a galvanic current, the magnetism will accu- 

 mulate in those parts of the bar nearest to the extremities 

 of the wire, and that the part of the bar opposite the middle 

 of the coil will be magnetically inactive; consequently when 

 one leg was magnetized it would have two poles, and that pole 

 adjacent to the inactive leg of the magnet would induce in it 

 also polarity ; consequently there would be two magnets in- 

 stead of one. If the two coils were in action at the same time, 

 each leg would be a separate magnet, and the magnetical con- 

 dition of the intermediate curved part would depend upon the 

 directions of the coils, and it might be a magnet also; conse- 

 quently there would be three magnets together, the power of 

 each being very uncertain. How far an experiment like this 

 is calculated to furnish scientific truth, 1 must leave to the 

 decision of your readers. 



I now come to what Dr. Ritchie designates the second false 

 principle. This is first called an assumption, and afterwards 

 a deduction. This part of the subject relates to the reaction 

 of the keeper upon the magnet. It was the subject of my first 

 short paper, but has been discussed more fully in the subse- 

 quent ones. 



The following experiments are directly connected with 

 magnetic reaction, and are, I think, illustrative of tlie exist- 

 ence of such a property. Take two keepers of the same form. 

 I>et tiie one consist entirely of soft iron, and the ends of the 

 other be made of iron, but the intermediate part of brass, as 



in the annexed diagram i rz;/«i^S- — i ; apply these keepers 



separately to the extremities of a hard single horseshoe mag- 

 net well magnetized, and it will be found that the iron one 

 holds, as nearly as can be estimated, double the weight of the 

 iron and brass one. It will be perceived that the interrupted 

 keeper will have its attractive force dej^endent entirely upon 

 the induction of the poles of the magnet, and that the weight 

 sustained will be a correct measure of the sum of the attraction 

 of the poles, whilst the uninterrupted keeper will have its at- 

 traction doubled by the induction which takes place in con- 

 sequence of the action of one end of the keeper upon the 



