Memoirs presented to the Cambridge philosophical society on the occasion of the jubilee of Sir George Gabriel Stokes, bart., Hon. LL. D., Hon. SC. D., Lucasian professor.

DISCHARGE OF AN AIR CONDENSER, WITH A DETERMINATION OF "v." 175
List of condensers used in the preliminary experiments with their capacities as
directly measured ballistically or estimated from their dimensions.
Capacity.
Cylinder condenser, already described, 5'5 K0 metres.
11 plate disc condenser,,, 0 0
5 plate disc condenser, part of the above 20
A Leyden jar about 20'5
A flat sheet glass and tinfoil condenser about 1900
or as found by calculation 237,
A large paraffin paper condenser by Muirhead,
consisting of six 2 microfarad condensers
arranged in series about 3000
After several preliminary photographs at various speeds and modes of connexion we
took on 22nd July a careful series of spins with the fork adjusted exactly at 128 and
with the 4 pattern of the disc extremely steady.
The connections were made as in Figure 8.
L being the self induction coil.
C and C' the condensers arranged close together.
S the spark gap in the dark box, and M the electrical machine.
The point E was sometimes earthed.
Connexion/:~~Fm 8ith t
/C M
FIG. 8.
Connexion w p ith the machine was made through wooden penholders w, in order to
always done, and it is this circumstance which was specially varied; the object being
to test the influence of wooden connexions, for subsequent use; e.g. with a guard-ring
condenser; where wooden connexion might preserve the potential uniform during slow
charge but isolate the guard-ring during sudden discharge.
The following are the circumstances of the chief plates taken this day.