If in motion, their motion implies energy, but it is not only their energy which is concerned in the wave making, but the acceleration, positive or negative-i.
"Hertzian Wave Wireless Telegraphy"
John Ambrose Fleming
Large doses produced this effect at once, without any previous acceleration.
"On Snake-Poison: its Action and its Antidote"
A. Mueller
Rocking, creaking, quivering to the dangerous rate of acceleration Kenniston was maintaining, the little ship rushed ahead.
"The World with a Thousand Moons"
Edmond Hamilton