W. G. Gady— Electric Arc hetween Metallic Electrodes. 249 



mental frequency about 240,000. The loss in mass of the 

 copper cathode was 0*018 gram, corresponding to a loss per 

 period of 2'1 X 10" 11 gram. This is the mass of about 

 S'SxlO 11 atoms of copper. 



§ 31. Oscillating system in parallel ivith the discharge. — 

 It seemed of interest to try the effect on the discharge of con- 

 necting in parallel with it a capacity and self-inductance. I 

 have not been able to obtain anything except oscillations of the 

 Duddell type under these conditions, in fact the glow-arc 

 oscillations seemed much diminished in intensity, while the 

 direct current of the supply increased on closing the condenser 

 circuit. The discharge became steadier and more like a stable 

 arc in appearance. 



§ 32. Radiation of energy from the discharge circuit. — 

 With a discharge between copper terminals in air, giving 

 oscillations feeble and of low frequency in comparison with 

 those later used, an ordinary telephone receiver emitted a 

 rustling sound when held more than a meter distant from the 

 discharge. The receiver was connected between two straight 

 wires, each 60 c<n long, terminating in tin sheets 10 cm square, 

 which served as a detecting system. 



From the same discharge, radiations were transmitted to a 

 bolometer four meters distant. They were greatly strengthened 

 by placing a large concave mirror behind the discharge. 



Using the stronger oscillations of oar later experiments, the 

 bolometer was found to respond when 35 meters away from 

 the discharge circuit. The discharge current itself was carried 

 vertically up the outside of the laboratory for a distance of 

 twelve meters, the circuit being completed inside the building. 

 The energy radiated from this " aerial " was received by a 

 second aerial nine meters high at a neighboring house, and the 

 bolometer was connected between this and the ground. 



Summary. 



1. The apparatus is described for producing glow-arc oscil- 

 lations of high frequency. Either alternating or direct e.m.f. 

 may be used. 



2. A number of experiments are described, using incandes- 

 cent lamps or hot-wire ammeters, demonstrating some of the 

 effects of these high-frequency currents and their upper har- 

 monics. 



3. Under favorable circumstances 66 per cent of the energy 

 supplied to the discharge can be converted into oscillating 

 currents. 



4. The frequency of the fundamental wave observed in 

 most cases was of the order of a quarter of a million. 



