150 hertz's researches on electrical waves. 



iiDtil a conductor, G, was attached, to the freeeud, h, of thecopjier wire, 



when they increased to 1 or 2 milli- 

 meters in length. That the action of 

 G was not an electrostatic one was 

 shown by its producing no effect when 

 ^ — — — ^ attached at g instead of at h. When 

 the knobs of the discharger B were 

 so far separated that no sparking took 

 place there, the si)arks at M were also 

 found to disappear, showing that these 

 were due to the sudden discharges and 



— UrvJ 



flf 



CXZZZHZX) not to the charging current. The 

 sparks at the <lischarger which pro- 

 duced themost effect atthemicrouieter 

 were of the same character as those 

 describe<l in my last paper. Sparks 

 were also found to occur between the 



^ _ nucrometer circuit and insulated con- 



FiG. 3, 



ductors in its vicinity. The sparks 



became much shorter when conductors of larger capacity were attached 

 to the micrometer knobs, or when these were touched by the hand, show- 

 ing that the quantity of electricity in motion was too small to charge 

 these conductors to a similarly high potential. Joining the micrometer 

 knobs by a wet thread did not perceptibl;y diminish the strength of the 

 sparks. The efl'ects in the micrometer circuit were not of sufiticient 

 strength to produce any sensation when it was touched or the circuit 

 completed through the body. 



In order to obtain further confirmation of the oscillatory nature ot the 

 current in the circuit lei h g (Fig. .i), the conductor G was again attached 

 to h, ami the micrometer knobs drawn apart until sparks only passed 

 singly. A second conductor, C", as nearly as possible similar to G, was 

 then attached to I', when a streamof sparks was immediately observed, 

 and it continued when the knobs were drawn still further apart. This 

 effect could not be ascribed to a direct action of the portion of circuit 

 * 1c, for in this case the action of the portion of circuit g h would be 

 weakened, and it must therefore have consisted in G' acting on the dis- 

 charging current of (7, a result which would be quite incomprehensible 

 unless the current in g h were of an oscillatory character. 



Since nn oscillatory motion between G and G' is essential for the pro- 

 duction of powerful inductive effects, it will not be sufficient for the 

 spark to occur in an exceedingly short time, but the resistance must at 

 the same time not exceed certain limits. The inductive effects will there- 

 fore be excessively small if the induction coil included in the circuit 

 G G' is replaced by an electrical machine alternately charging and dis- 

 charging itself, or if too small an induction coil is used ; or again if the 

 air space between the discharger knobs is too great, as in all these cases 

 the motion ceases to be oscillatorv. 



