In the summer of 1940, as the world plunged deeper into war, the Secret Service escorted an eccentric engineer named J. Ripley Kiel into the Oval Office.

Kiel had recently invented a small machine that could record sound via remote control. When a White House aide heard about the contraption, he thought it could allay one of President Franklin D. Roosevelt’s cardinal fears — that he’d be misquoted during a press conference or meeting, further endangering the world.

Roosevelt signed off.

“The tall lamp on his desk was not suitable for hiding a microphone,” wrote William Doyle, in his book about Oval Office recordings,“so Kiel bought another one and hid the microphone in it. When switched on, the machine was noise activated, and began recording as soon as someone spoke or made a loud noise.”

With the country riveted by the recent disclosure of a secret recording of then-presidential candidate Donald Trump by his former lawyer and fixer Michael Cohen, the Roosevelt taping apparatus is, according to historians and surveillance experts, instructive in several ways.