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 the 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 

 of special direct- 

 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 batteiy 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 



Fig. C. 



