122 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 
primary condenser circuit is closed by the stud filling the gap between 
the side disks; but after this the opening of the gap at the disks 
prevents the energy returning to the condenser circuit from thé aerial, 
as would happen were the ordinary spark gap employed. In this 
manner the usual reaction which would take place between the aerial 
and the condenser circuit can be obviated, with the result that with 
this type of discharger and with a suitable degree of coupling the 
energy is radiated from the aerial in the form of a pure wave, the 
loss from the spark gap resistance being reduced to a minimum. 
I am able to show a resonance curve taken at Clifden which was 
obtained from the 
oscillations in the 
primary alone (fig. 
5). 
An interesting 
feature of the Clif- 
den plant, espe- 
cially from a prac- 
tical and engineer- 
ing point of view, 
is the regular em- 
ployment of high- 
tension direct cur- 
rent for charging 
the condenser. 
Continuous cur- 
rent at a potential 
which is capable 
of being raised to 
20,000 volts is ob- 
tained by means 
ARGER of special direct- 
rs | current genera- 
tors; these ma- 
chines charge a 
storage battery consisting of 6,000 cells, all connected in series, and 
it may be pointed out that this battery is the largest of its kind in 
existence. The capacity of each cell is 40 ampere-hours. When 
employing the cells alone the working voltage is from 11,000 to 12,000 
volts, and when both the direct-current generators and the battery 
are used together the potential may be raised to 15,000 volts through 
utilizing the gassing voltage of the storage cells. 
For a considerable portion of the day the storage battery alone is 
employed, with a result that for 16 hours out of the 24 no running 
DISK DISCH 
nTRUOUS it 
Fa. 6. 
