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In the absence of Chairman Geo. W. Parsons, Mr. Wm. H. Knight 

 presided. Tne minutes of the preceding meeting of the Section were read 

 by the Secretary and approved. 



The meeting was addressed by Mr. Fred H. Brown on "Detecting 

 the Presence and Ivocating the Position of Ore Bodies in Mineral Veins by 

 Electricity." It was interestingly illustrated by means of electrical apparatus, 

 numerous charts and blackboard diagrams. 



Mr. Brown said that the principle involved is the well-known law 

 that an electrical current always seeks the path of least resistance. The 

 metals are good conductors, while the earth is a poor conductor and oflFers a 

 comparatively high resistance. If a current is sent from a point A to a 

 point B, 500 feet distant, and the resistance recorded by the ohm-indicator is, 

 say 1000 ohms, while a currant sent from A to point C in another direction 

 encounters a resistance of only 200 ohms, the inference is that somewhere 

 below the surface between A and C there is a body of metallic ore offering a 

 low resistance to the current. B^^ repeated cross-sectional surveys the 

 depth and position of the ore body can be approximately determined. 



Beautiful experiments, illustrating the principles involved were, 

 made with copper fillings, with a mass of galena two feet in diameter, and 

 with a chalk-like substance which proved to be nearly a non-conductor. 

 Mr. Brown was assisted in his experiments by Messrs. J. A. Shelhamer and 

 Wm. D. Kelly. An animated discussion was participated in by Messrs. J. 

 H. Dockweiler, G. Major Taber, E B. Avery, W. W. Webster of Pasadena 

 and others. G. Major Taber, Secretary. 



