406 PROCEEDINGS OP THE AMERICAN ACADEMY 



that even a short length of conductor opposes the flow of current by 

 its self-induction so greatly that lamps are lighted in a shunt to it, 

 cards punctured, etc. (Figure 2). In fact, in one experiment an incan- 

 descent lamp was lighted in shunt to about 18 inches of \ inch copper 

 rod, and the lamp was brought to full brilliancy (Figure 3). More- 

 over, it was distinctly shown that these currents are comparatively 

 harmless, and may be passed through the body in an amount sufficient 

 to light fully ordinary incandescent lamps (Figures 4 and 5) ; and the 

 speaker stated that from the extremely small sensation experienced he 

 thought it would be easily possible greatly to increase the current, and 

 probably to an extent sufficient to light a small arc lamp. 



The discharge circuit in this case had the form of a U of heavy 

 copper rod, and it could be grasped so as to short-circuit it between 

 points of such potential that insulation of considerable thickness would 

 be readily pierced ; but there was no disagreeable sensation, and very 

 little sensation at all experienced. 



The extraordinary energy of the induction of these dischai'ges in 

 the U-shaped conductor was shown by bringing near to it a rectangle 

 of heavy copper wire the circuit of which was completed through 

 a large incandescent lamp requiring more than one third of a horse- 

 power of electrical energy to light it. It was found that the incandes- 

 cent lamp could be brought far beyond its normal brilliancy on placing 

 the rectangle a few inches away from the U (Figures 6 and 7). 



By causing the condenser discharges to pass the air gaps and also a 

 large open coil of about ten turns immersed in oil, the inductive effects 

 of such coil on a parallel secondary coil having about 460 turns were 

 exhibited. This secondary coil of 4 GO turns was wound on a hard 

 rubber frame as a single layer, and the turns kept apart by a small 

 space, and together with the primary immersed in a box or bath of oil 

 of high insulating power (Figure 8). The ends of the finer and longer 

 secondary were carried to the terminals rising out of the oil at the ends 

 of the box or bath, and between these terminals torrents of sparks of 

 about 30 inches in length were produced, accompanied by a loud roar- 

 ing or crashing sound. Lateral discharges from the terminals were 

 shown to be capable of being received through the body without injury, 

 although of sufficient energy of current to light fully an incandescent 

 lamp (Figure 9), and in fact to melt off the ends of fine wires, set fire 

 to sticks of wood, etc. In this connection it was shown also that water 

 was for these discharges a comparatively fair insulator, inasmuch as the 

 sparks could be made to pass under water with substantially the same 

 appearance as when they passed through air. Disruptive sparks as 

 well as brush discharges were produced under water*. 



