270 
Mr.  A.  Russell  on  the 
(vi.)   C.  P.  Steinmetz.     I'll  inch  cylindrical  electrodes. 
.Experiments  were  also  made  with  large  cylinders  1*11  inch 
in  diameter  and  20  inches  long.  Up  to  a  distance  apart  o£ 
about  one-third  of  an  inch  we  may  assume  that  our  formula 
applies  approximately. 
We  have  neglected  therefore  the  experimental  results  for 
greater  distances.  The  mean  of  the  values  of  Rmax.  deduced 
from  the  first  five  experiments  is  31  kilovolts  per  centimetre. 
We  do  not  attach  so  much  importance  to  this  result  as  to  the 
preceding  as  our  formula  does  not  apply  so  accurately. 
14.    Table  of  the  Numbers  obtained  for  the  Dielectric  Strength 
of  Air  from  the  Direct  Pressure  Experiments. 
Table  XI. — Direct  Pressures. 
Nature  of  Electrodes. 
Authority. 
^max. 
Table  VII... 
5  cin.  spheres. 
J.  Algermissen. 
37-0 
Table  VI.  ... 
5  cm.  spheres. 
A.  Heydweiller. 
37-5 
§  is,  i.,  i. ... 
Slightly  convex  surfaces. 
Lord  Kelvin. 
40-8 
§13, 1.,  v.... 
1  cm.  spheres. 
E.  Hospitalier. 
42-2 
§13,1.,  iv... 
1     „         „ 
J.  Joubert. 
42-8 
5!               5J 
2 
G.  Carey  Foster. 
42-9 
Of  the  above  tests  the  first  three  seem  to  be  the  most 
accurate.  The  mean  of  the  results  obtained  from  these  three 
tests  makes  the  dielectric  strength  of  air  38'4  kilovolts  per 
centimetre. 
15.   Table  of  the  Numbers  obtained  for  the  Dielectric  Strength 
of  Air  from  the  Alternating  Pressure  Experiments. 
Table  XII.- 
■Alternating  Pressures. 
Nature  of  Electrodes. 
Authority. 
^max. 
§  13,  II.,  vi. 
I'll  inch  cylinders. 
C.  P.  Steinmetz. 
34 
§  13,  II.,  ii. 
2  cm.  spheres. 
Comp.  de  llnd.  Elect. 
37-9 
Table  IX. 
2  inch  spheres. 
C.  P.  Steinmetz. 
37-8 
Table  X. 
0"313  inch  cylinder. 
)5 
38-8 
§  13,  II.,  iii. 
1  inch  spheres. 
!) 
41-3 
