Origin of spark gap
Examples from the Web for spark gap
Then he told her how to adjust her spark-gap and tune the instrument to any given wave-length.
Almost immediately after Dawson disappeared the crash of the spark across the spark-gap and up the wires was heard.
Chub grabbed the key and rattled away at it until the spark-gap was fairly blue.Motor Matt; or, The King of the Wheel|Stanley R. Matthews
The crash of his call soon sounded at the spark-gap and quivered on its lightning way up the aerials.
While Lew was writing down for him the wireless alphabet, Charley was showing him how to make the letters on the spark-gap.