FAKMEES' INSTITUTES. 345 



DR. KEDZIE CEITICISED. 

 From the Coluwater Rcpxiblicaii. 



Dr. Kedzie, in liis "talk on lightning-rods" before the farmers' institute in 

 this city, on Thursday evening, Jan. 20, not only left many of his hearers in 

 doubt regarding his belief in the efficiency of lightning-rods, but advanced one 

 theory, at least, that cannot be sustained by any other authority outside of the 

 doctor's pronounced statement, and even that unsupported by argument or 

 illustration, always desirable where a change is sought to be made in any seem- 

 ingly well established theory or fact. I allude to his statement that "the 

 extent of surface in a rod has no connection with its conducting power," that 

 "electricity does not pass upon the surface of the conductor," and "that a 

 round rod, solid in form, will conduct an equal amount of electricity -svith that 

 of a hollow tube containing the same amount of metal but a largely increased 

 surface." 



After having devoted a considerable portion of my time to the investigation of 

 this and kindred subjects, for the past 20 years, and having received as correct 

 the teachings of men of more than state reputation, — of men whose irablished 

 works are used as text-books in our schools and colleges, and carry with them 

 weight throughout the scientific world, — I was surprised at the position assumed 

 by a man of the doctor's intelligence and pronounced ability as a teacher in one 

 of our most important state institutions. The doctor was correct in assuming 

 that the fluted form was given to the rod exhibited by him, solely to increase its 

 surface, and consequently conducting power ; and I will now quote briefly from 

 authorities (any one of which the doctor's position in the scientific world will 

 hardly authorize him to question), relied upon to sustain a theory entirely differ- 

 ent from that advanced by him upon the occasion referred to. 



The distribution of electricity in an excited body is upon tlie surface.— [Silliman's 

 Chemistry. 



Wlien electricity is communicated to a conducting body, it resides merely upon the 

 surface, and does not penetrate to any depth within.— [Well's Nat. Philosophy. 



When electricity is communicated to a conducting body, it does not distribute 

 itself uniformly through the wliole mass, but exclusively upon the surface. — [Draper's 

 Chemistry. 



When a body is electrified, the fluid with which it is charged lies at the surface of 

 the body, and not at all within the surface. Hence electrical conductors, when hol- 

 low, will contain just as great a charge of electricity as when solid. — [Olmstead's 

 Philosophy. 



The experiments of Coulomb demonstrate that conductors contain all their elec- 

 tricity upon their surface, that is, the mass of metal cannot receive electricity, but 

 only the surface of that mass. Therefore, the best conductor (of the same metal) will 

 be the one that exposes the most surface. The thickness of the metal has nothing to 

 do with its conducting power. — [Memoirs d'Academie. 



Electricity passes entirely upon the surface of metals. A copper tube of one-half 

 an inch in diameter, will conduct nearly twice as much electricity as covild be carried 

 away by a bar of copper of the same diameter. — [General Science. 



Experiment teaches us that electricity is exhibited only on the surface of bodies. — 

 [Chambers' Encyclopjedia, vol. iii, page 814. 



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

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

 bers' Encyclopaedia, vol. iii, page 816. 



It hath already been shown that the electric matter runs over the surface of con- 

 ducting substances, in great quantities, lilve a stream of water running from one place 

 to another. — [Cyolopffidia Britannica, vol. vi, page 456. 



Experiments of that electrician. Coulomb, demonstrate that conductors carry all 

 their electricity upon the surface; that solidity (metal as a mass) cannot receive 

 electricity. — [Cyclop.iedia Brittannica, vol. x, page 60. 



Tubes for a given amount of metal expose the greatest surface and thus furnish the 

 maximum capacity of conduction of the electrical current. — [American Cyclopaedia, 

 vol. X, page 528. 



