Mr. R. Phillips on Volta-Electric Induction. 261 



netized and suspended so as to form a partially astatic arrange- 

 ment. The battery was one on Smee's construction ; it con- 

 sisted of six repetitions, and the immersed portion of each 

 plate was about 4- inches by 3*5 inches. Throughout these 

 experiments the battery current always passed in the same 

 direction with regard to the convolutions of the indicator. 



One of the coils A was laid horizontally on a table, and the 

 coil B upon A; the ends of A were in communication with 

 the indicator, one end of B with a wire from the battery, and 

 the other end of B dipped into some mercury into which the 

 other galvanic pole could be plunged. A needle was now 

 placed in the indicator, the battery circuit completed, and the 

 needle removed ; the point of the needle was found as the 

 marked end of a magnet. 



The battery current was now sent through B, then the 

 needle was placed in the indicator and the battery circuit 

 broken, when the eye end of the needle was the marked mag- 

 netic end. 



A needle was now placed in the indicator, and the battery 

 circuit made and broken, when the eye end of the needle be- 

 came as the marked end of a magnet. In these three cases 

 the magnetism was very strong and apparently equal. 



These induced currents circulate in the same direction as 

 pointed out by Dr. Faraday, but their law of relative force is 

 entirely different; for he found that " when the unmagnetized 

 needle was put into the indicating helix, before contact of the 

 inducing wire with the battery, and remained there until the 

 contact was broken, it exhibited little or no magnetism ; the 

 first effect having been nearly neutralized by the second. The 

 force of the induced current upon making contact was found 

 always to exceed that of the induced current at breaking of 

 contact*." 



When the coil A was connected with a galvanometer instead 

 of the indicator, then closing the circuit through B, caused the 

 ends of the galvanometric needles to start through a space of 

 about gVh of an inch, and the same on breaking the circuit ; 

 but when the end of the wire was rapidly plunged into and re- 

 moved from the mercury, the needle appeared to make only 

 an abrupt and barely perceptible motion on the circuit being 

 completed. This agrees with the equality which Dr. Faraday 

 and all who have followed him have found ; so that although 

 different helices give the two induced currents as various 

 forces measured by the indicator, yet, as measured by the 

 galvanometer, they are respectively very equal. This can only 

 arise from the two induced currents being about equal in 

 * Experimental Researches in Electricity, vol. i. p. 4. 



