Rood — Experiments on High Electrical Resistance. 97 



having been arranged so that only units or sets of units of 

 about the same resistance were compared together, it was pos- 

 sible to run through the entire series in three hours, and on 

 April 20th this was done, and repeated on April 21st. The 

 number of readings in no case exceeded three ; the striking 

 distance was one millimeter. The degree of accuracy obtain- 

 able under such circumstances can be judged from the table 

 here given, where the resistances are expressed in megohms. 



April 21st. 



April 22d. 



34,000 



34,000 



12,580 



12,260 



23,910 



24,140 



26,970 



27,200 



73,580 



73,460 



190,560 



189,700 



217,800 



220,800 



440,200 



431,400 



520,400 



517,600 



1,420,200 



1,420,000 



1,849,000 



1,761,200 



1,862,400 



1,645,400 



2,570,000 



2,360,000 



4,768,000 



4,944,000 



6,364,000 



6,110,000 



7,432,000 



7,092,000 



14,658,000 



13,724,000 



lumbia University, New York, 



June 1st* 1901. 



