290 The N.Z. Journal of Science and Technology. [Jan. 
Tae accurate theoretical calculation of the effects to be expected becomes 
increasingly difficult with the number of wires involved owing to mutual 
electrostatic-capacity effects. 
Actual measurements were also made on the telephone-lines L, M, N, 0. 
Lengths of 24 chains were isolated, and the following are the results 
obtained:— 
Table III. 
State of 
Transmission-line . 
Wires. 
Observed 
Voltage. 
Calculated 
North Line. 
South Line. 
Voltage. 
Phase Angle. 
North Line Telephone. 
Dead 
Alive 
N-earth . . 
195 
313 
/187° 20' 
O-earth . . 
175 
293 
/I85° 26' 
N-0 
22 
/212° 17' 
Alive 
Alive 
N-earth . . 
1645 
3379 
/311° 20' 
O-earth .. 
1785 
3531 
/279° 48' 
N-0 
940 
1883 
/30° 1' 
Alive 
Dead 
N-earth .. 
1697 
3564 
/44° 30' 
O-earth .. 
1730 
3565 
/75° 3D 
N-0 
920 
1906 
/30° 2' 
, — : 
South Line Telephone. 
Alive 
Dead 
L-earth . . 
150 
280 
/54° 54' _ 
M-earth .. 
153 
293 
/54° 38' 
__ 
L-M 
. • • 
13 
/231° 20' 
Alive 
Alive 
L-earth .. 
1795 
3590 
/338° 45' 
M-earth .. 
1805 
3375 
/320° 10' 
L-M 
320 
1147 
/48° 26' 
Dead 
Alive 
L-earth .. 
1850 
3541 
/25° 39 / 
M-earth .. 
1775 
3411 
/44° 45' 
L-M 
330 
1159 
748° 28' 
Column 5 gives the calculated values, using Parry’s formula and 
assuming that the capacity of L, say, is the same per unit-length as for 
an infinite isolated wire far removed from M. However, in this case agree¬ 
ment between the calculated and theoretical values cannot be expected. 
The influence of M is undoubtedly to increase the capacity of L, as also 
are the earth wires up the poles and along the arms AC and the remainder 
of the telephone-line which continues from the same transposition insulators. 
Further, it is well known that the end effects of a short length of wire 
such as was used will also increase the capacity. This, as has been shown 
above, will tend to produce a result less than that calculated from Parry’s 
formula. 
It is hoped in further experiments to actually determine the various 
electrostatic capacities experimentally, and to make a more exacting com¬ 
parison between theory and observation. 
