THUNDERBOLTS 141 



thought of him as using in his cloudy home the familiar 

 bow and arrow of this nether planet. To us nowadays, if 

 we were to begin forming the idea for ourselves all over 

 again de novo, it would be far more natural to think of the 

 thunder as the noise of a big gun, of the lightning as the 

 flash of the powder, and of the supposed ' bolt ' as a shell 

 or bullet. There is really a ridiculous resemblance between 

 a thunderstorm and a discharge of artillery. But the old 

 conception derived from so many generations of primitive 

 men has held its own against such mere modern devices 

 as gunpowder and rifle balls ; and none of the objects 

 commonly shown as thunderbolts are ever round : they 

 are distinguished, whatever their origin, by the common 

 peculiarity that they more or less closely resemble a dart 

 or arrowhead. 



Let us begin, then, by clearly disembarrassing our 

 minds of any lingering belief in the existence of thunder- 

 bolts. There are absolutely no such things known to 

 science. The two real phenomena that underlie the fable 

 are simply thunder and lightning. A thunderstorm is 

 merely a series of electrical discharges between one cloud 

 and another, or between clouds and the earth ; and these 

 discharges manifest themselves to our senses under two 

 forms to the eye as lightning, to the ear as thunder. All 

 that passes in each case is a huge spark a commotion, 

 not a material object. It is in principle just like the spark 

 from an electrical machine ; but while the most powerful 

 machine of human construction will only sen,d a spark for 

 three feet, the enormous electrical apparatus provided for 

 us by nature will send one for four, five, or even ten miles. 

 Though lightning when it touches the earth always seems 

 to us to come from the clouds to the ground, it is by no 

 means certain that the real course may not at least occa- 

 sionally be in the opposite direction. All we know is that 



