6¢ Marconi’s Spark Coil & Gap
Electronics Progress Issue
Issue Date: July 10, 1973
City: New York, NY
Printed By: Bureau of Engraving and Printing
Printing Method: Lithographed, engraved
Color: Lilac and multicolored
Issued to commemorate the progress made in electronics, this stamp features Guglielmo Marconi's spark coil and spark gap, which enabled him to transmit across the Atlantic Ocean by wireless radio.