PROCEEDINGS OF THE FARMERS' CLUB. 221 



masses of matter, silently and without producing any manifest 

 eflfects; the effect of insulation is to interrupt the flow of these 

 currents, whereas the lightning rod ought rather to be so con- 

 trived as to facilitate their free passage from the building to the 

 rod, and thence to the atmosphere, and vice versa. 



"During that disturbed electrical condition of the atmosphere, 

 which we call a thunder-storm, these currents circulate in greater 

 volume and rapidity, and a sufficient interruption of them brings 

 about a discharge of lightning. 



" At such times the insulation of the rod from the building is 

 a most excellent device for causing an explosion of accumulated 

 electricity either from or into the building, as the case may be. 

 The rod, on the contrary, ought to act somewhat as a safety 

 valve as regards any electrical disturbance within the house, 

 neutralizing it gradually, and thus preventing an explosion. 



" Should the rod be struck by lightning, its efficacy in carrying 

 off the shock will depend on whether it presents a continuous 

 chain of conducting matter in the line or direction of the dis- 

 charge, which is superior to anything within the building. If it 

 does not, all the glass in the world will . not prevent fluid from 

 leaving the rod and passing through the building on such con- 

 ductors as it may find there. 



" The true theory or purposes of the lightning rod is to facili- 

 tate electricity in following out its natural laws and tendencies, 

 and nothing can be more truly unscientific or practically absurd 

 than the idea of presenting a barrier or obstruction to lightning?" 



All my reading and observations so far has taught me that this 

 is the true theory ; and, happily, to confirm me in it, I have re- 

 ceived the following letter at the very moment while engaged in 

 penning the above. It comes from S. D. Cushman, of South Bend, 

 Ind., who has made electricity a study, and the following is his 

 opinion about lightning rods. He says : 



A conductor for the protection of life and property from the 

 effects of lightning, should be so constructed and applied that it 

 will add to the conducting power of the building, so as to 

 admit of the most intense discharge being securely transmitted 

 without explosion or damage to the building or structure. 



Attraction. — The utility of a lightning rod does not consist in 

 its attracting power. 



Insulation. — The conducting power of a lightning rod is fre- 

 quently diminished by insulation, and never is increased ; it 



