TKflireless aelearapbg. 183 



takes place between the earth and cloud the 

 potential between the two will suddenly be- 

 come equalized and the static charge that was 

 accumulated in the earth is released and it 

 dissipates in every direction, seeking an equi- 

 librium, following the analogy of the water; 

 the difference being that in one case the move- 

 ment is very slow, while in the other it is as 

 " quick as lightning." 



About eighteen years ago I had a short tele- 

 phone-line between my ^ouse and that of one 

 of my neighbors. This line was equipped with 

 what was known in those days as magneto- 

 transmitters, such as we have described in a 

 previous chapter on the subject of telephony. 

 When a line is equipped in this way no bat- 

 teries are needed, as the voice generates the 

 current, on the principle employed in the 

 dynamo-electric machine. Often on summer 

 evenings, when the sky appears to be cloudless, 

 we can see faint flashes of lightning on the 

 horizon, an appearance which is commonly 

 ! "heat-lightning." As a matter of fact, 

 I do not suppose there is any such thing as 

 heat-lightning, but what we see i- the effect of 

 nn-clouds. Often at such times 

 I have held the telephone receiver to my ear 

 and couM hear -imiiltaiie.,u-ly with each flash 

 a slitrht sound in the telephone. This effect 

 couM !>< pro.liieed in the earth by a simple dis- 

 charge between two or more clouds, which 



