246 STATE BOAED OF AGEICULTUKE. 



The number of unquestioned authorities might be multiphed, but space will 

 not permit in a newspaper article. The foregoing, however, are sufficient to 

 illustrate either the erroneous teaching of the past century, amply sujDported as 

 it has be3u by experiments and exjoerience, or the error of the doctor in his 

 position regarding the conducting power of the surface of metals when utilized 

 in the form of the modern lightning conductor. 



January 22, 1S7G. 



A. T. Lanphere. 



EEPLY BY DR. KEDZIE. 



To the Editor of the Lansing Republican: 



Most of the authorities quoted by Mr. Lanphere to sustain his position that 

 electric conduction is a surface action, and that it does not pass through the 

 mass of the metal in a conductor, are treating of static electricity, or electricity 

 standing still, and not of electricity in motion, which is the form with which 

 we have to deal in lightning. I pointed out the difference between static elec- 

 tricity and lightning, so far as conduction is concerned, at the institute at 

 Coldwater. These authors are speaking of the distribution of static electricity 

 on the sruf ace of an insulated prime conductor, in which case it is confined to 

 the surface. 



But if electricity in motion is also confined to the surface and has nothing 

 to do with the mass of metal in a conductor, how can Ave explain the com- 

 mon experiment of dissipating in an imjialpable dust a large surface of gold 

 leaf by a discharge from an electrical battery? Would a solid gold bar of the 

 same extent of surface be thus burned up? In the case of the gold leaf we 

 have a large amount of surface, but not enough mass of metal to carry away 

 even this small amount of electricity. Again, how can we explain the fact that 

 we can readily pass a charge of electricity through a wire fused into a j)iece of 

 non-conducting glass ? Such wires are fused into our eudiometer tubes, yet we 

 find no trouble in sending, a spark through such wires. 



But let us compare some of the authorities quoted with each other : 



We learn from these and numerous other experiments that electricity is only found 

 on the outer surface of conductors, in an envelope of inappreciable thickness. [Cham- 

 bers' Encyclopaedia, vol. iii, page 816. 



A copper tube of one-half inch in diameter will conduct nearly twice as much electric- 

 ity as could be carried away by a bar of copper of the same diameter. [General Sci- 

 ence. 



Now^ will •'General Science" or Mr. Lanphere tell me how much greater is 

 *'the outer surface" (where "only electricity is found") of a copper tube than 

 that of " a bar of copper of the same diameter?" Has not " Gen. Science " been 

 captured by Capt. Ignorance? 



Mr. Lanphere intimates that I "advanced one theory at least that cannot be 

 sustained by any authority outside of the doctor's pronounced statement," viz., 

 that electrical conduction is not a mere surface action. I did not quote author- 

 ities to sustain my position because this theory is now so generally received by 

 scientific men that I did not think it necessary, to quote autliorities. The 

 authorities quoted by Mr. Lanphere, which are of any weight, are old and 

 antiquated 



The masterly researches of Coulomb and Faraday have indeed forever settled 

 the question that in static electricity the whole of the electricity resides on the 

 surface of an insulated conductor. Some of their cotemporaries assumed that 



