1902.] 



Disturbances, and their Origin. 



227 



the atmosphere and the ionisation produced by the sun suggests the 

 source of the other daj^time disturbances referred to. It appears 

 highly probable that the}^ are the accompaniment of the clearing up 

 process. Effects analogous to, if not actually, electric currents are 

 doubtless produced in the atmosphere, which are induced in the sea 

 and collected by the circuit. On the other hand, the nightfall dis- 

 turbances are probably due to normal clearing up processes, revealed 

 when the air becomes sufficiently non-conducting to act no longer as 

 a screen. These suggestions, though by no means complete, are sub- 

 mitted for what they may be worth. 



It is probable also that the diurnal variations of the earth's magnetic 

 field are influenced by the same causes. 



One more point. The periods of maximum disturbances, experi- 

 enced on the earthed circuits referred to, appear to coincide with 

 periods of maximum atmospheric disturbances on the newer Hertzian 

 system of wireless telegraphy, and indicate the same source of trouble. 

 Further, I would suggest that we have here a clue to the true explana- 

 tion of the greater night-time efficiency in signalling observed by 

 Mr. Marconi in recent experiments. With ionised air the electric 

 waves will be partly broken up and absorbed, with consequent abstrac- 

 tion of energy from the transmission. At night, when the ionisation 

 is cleared up, the strength of the radiated waves will be sustained. 



Some interesting investigations by the aid of sounds produced, in a. 

 telephone, by the passage of electrical currents through panned gases 

 can no doubt be carried out. Professor Righi has already made some 

 observations in this connection, but much more can yet be done. 



