328 



Mr. W. P. Boynton on the 



The maximum potential was tested, roughly,- by the 

 measurement of spark-lengths, using for potentials of less 

 than 30,000 volts determinations made by myself with the 

 alternating current upon the absolute electrometer ; higher 

 potentials were taken from curves drawn from data given by 

 Heydweiller *, potentials above 50,000 volts being obtained, 

 when necessary, by extrapolation. 



In the accompanying Table II., which gives a few out of a 

 great number of determinations, column a gives the length of 

 the primary spark, b is the corresponding potential V , c is 

 the length of the secondary spark, d the potential corre- 

 sponding thereto, and e the ratio d/b, which should have for 

 its limit, as shown above, the value 21. The extreme values 

 found range from 1*3 to 2*74, with averages in different 

 groups of from 1*7 to 2*34. 



Table II. 



a. 



b. 



c. 



d. 



e. 



•8 



24,500 



319 



53,100 



2-165 



t) 



lt 



2-84 



51,200 



2-09 



,, 



„ 



33 



53,700 



219 



,, 



fl 



25 



49,200 



201 



)} 



}f 



2-89 



51,500 



21 



,, 



,, 



2-11 



46,200 



1-88 



„ 



if 



2-25 



47,300 



1-93 



, 



»> 



207 



45,900 



1-87 



,, 



>) 



2 51 



49,200 



2 01 



„ 



,, 



2-4 



48,400 



1-97 



•6 



19,450 



1-87 



44,200 



2-27 



>> 



)} 



2-65 



50,400 



259 





M 



1-5 



40,400 



208 



>> 



,, 



1-28 



37,200 



1-91 



»> >» 



1-06 



33,000 



1-7 



„ ,, 



1-35 



38,400 



1-97 



„ 



1-24 



36,600 



1-88 



•4 13,650 



1-08 



30,400 



2225 



„ 



,, 



•75 



23,500 



1-72 



„ 



,, 



•68 



21,650 



2-585 



,, 



}) 



•775 



24,100 



1-76 



,, 



,, 



•78 



24,200 



1-77 



)> 



,, 



•725 



22,800 



1-67 



" 



,, 



•75 



23,500 



1-72 



>i 



,, 



•765 



23,900 



1-75 



•2 7,300 



•555 



18,300 



2-505 



„ }J 



•27 



9,500 



1-30 



)> »j 



•325 



11,300 



1-55 



,, 



j> 



•475 



16,000 



219 



" 



»> 



•375 



12,900 



1-77 



The measurements of the effective difference of potential in 

 the secondary circuit were made by means of a modified 

 * Wied. Ann. xlviii. p. 213 (1893). 



