330 Mr. R. Sabine on J featuring the Contour of 



Exp. 7. — Accumulator inserted at c' 190 knots from end a. 



Interval by disk. 



0*045 second 



0*046 „ 



0-047 „ 



0-048 „ 



0-049 „ 



0-050 „ 



0-051 „ 



0-052 „ 



0-053 „ 



Excursion of galvanometer- 

 needle. 

 — 12 divisions. 

 -10 



+ 



7 

 4 

 

 5 

 7 

 9 

 11 



Exp. 8. — Accumulator inserted at end of cable, 304 knots 

 from a, and a resistance of 100 ohms between b and earth. 



Interval by disk. 



0*04 second 

 0-05 „ 

 0-06 „ 

 0-067 „ 

 0-07 „ 

 0-08 „ 

 0-09 „ 

 0-10 „ . 

 Whatever may be the pi 



Excursion of galvanometer- 

 needle. 

 — 7 divisions. 

 -4 „ 

 -2 „ 

 „ 

 + 1 „ 

 2 „ 

 5 



;ecise effect of the cable being coiled, 

 upon the results, it is probably greater at the first moment 

 than afterwards. From this cause the time of the neutral 

 point crossing may be in exp. 6 higher than it would have 

 been had the cable been submerged, less so in exp. 7, and 

 least so in exp. 8. As it was, however, the times were as fol- 

 lows when the neutral point passed c, </, and b : — 



Point passed. Time. 



c (114 knots from a) . . . . 0*036 second. 



C(190 „ )..... 0-049 „ 



b (304 „ ) . . . . 0-067 „ 



Between c and c' the wave passed through 76 knots in 0*013 

 second, and between d and b 114 knots in 0*018 second. In 

 this sense we can say that in this identical 304 knots of coiled 

 cable, the wave in question travelled at the rate of about 6000 

 knots per second. 



In carrying out these experiments, I observed that the same 

 series repeated gave the same results. 



The accumulator employed was one made of mica plates with 

 tinfoil coatings and cemented with shellac. Its capacity was 

 0*33 microfarad, its resistance at the time of making the ex- 



