Dielectric  Strength  of  Air 
2§Z 
(iii.)    J.  Algermissen.     5  cm 
In  the  following  table  the 
spheres  (a  =  2'5  cm,). 
values  of  x  and  V  are  taken 
from  Dr.  Zenneck's  work '  Elektromagnetische  Schwingungen 
unci  Drahtlose  Telegraphie,'  1905,  p.  1011.  They  are  due  to 
J.  Algermissen,  and  are  deduced  from  the  average  of  the 
values  obtained  on  differ ent  days  under  varying  conditions. 
We  have  assumed  that  the  potentials  of  the  electrodes  were 
+  V/2  and  — V/2  respectively  at  the  instant  of  the  discharge. 
As  the  results  in  the  last  column  are  very  approximately 
constant  our  assumption  is  justified. 
Table  VII. 
J.  Algermissen.     5  cm.  spheres  (a  =  2*5). 
x  is  measured  in  cms.  and  Y  in  kilovolts. 
X. 
x/a. 
0^6 
/(calc.). 
V  (obs.). 
E-max.  (calc). 
1-5 
1-208 
46-2 
36-6 
1-6 
0-64 
1-223 
48-6 
36-5 
1-7 
0-68 
1-238 
51-0 
36-6 
1-8 
0-72 
1-253 
53-4 
36-6 
1-9 
0-76 
1-268 
55-8 
36-7 
2-0 
0-80 
1-283 
58-2 
36-8 
2-1 
0-84 
1-298 
60-6 
37-0 
2-2 
0-88 
J -312 
628 
36-9 
2-3 
0-92 
1-326 
65-0 
37-0 
2-4 
0-96 
1-342 
67-0 
37-0 
2-5 
1-00 
1-360 
69-0 
37-1 
2-6 
1-04 
1-374 
70-8 
37-0 
2-7 
1-08 
1-390 
72-6 
37-0 
2-8 
1-12 
1-406 
74-4 
37-0 
2-9 
1*16 
1-421 
76-2 
37-0 
3-0 
1-20 
1-437 
78-0 
37-0 
3-1 
1-24 
1-452 
79-7 
37-0 
3-2 
1-28 
1-469 
81-3 
37-0 
3-3 
1-32 
1-484 
83-0 
37-0 
3-4 
1-36 
1-500 
84-7 
37-0 
3-5 
1-40 
1-515 
86-4 
37-1 
3-6 
1-44 
1-533 
88-0 
37-1 
3-7 
1-48 
1-549 
89-6 
37-2 
3-8 
1-52 
1-566 
91-2 
37-3 
3-9 
1-56 
1-583 
92-7 
37-3 
4-0 
1-60 
1-599 
94-2 
37-4 
4-1 
1-64 
1-616 
95-7 
37-4 
4-2 
1-68 
1-632 
97-2 
37-4 
The  mean  of  the  values  of  Kmax.  in  the  last  column  gives 
the  dielectric  strength  o£  air  as  37*0  kilovolts  per  centimetre, 
and  the  greatest  difference  between  any  of  the  calculated 
numbers  and  this  value  is  only  about  one  per  cent.  It  will 
be  seen  therefore,  that  the  agreement  between  theory  and 
