Charles Emory Apgar (June 28, 1865 – August 17, 1950) was an American business executive and amateur radio operator.

[1] The recordings that he made of a wireless telegraphy station owned by a German Empire-based company operating from the United States were used to expose an espionage ring.

An editor of a magazine was so impressed that he enthusiastically described it as "One of the greatest feats ever produced by any amateur..."[14] Apgar also devised a method to record the signals from stations that he listened to.

"[11] Apgar's equipment was mostly homemade with the exception of the headphones and of an improved Audion designed by Edwin Howard Armstrong that was part of the circuit used to detect and amplify the signal.

[20] It was connected to a Dictaphone which allowed him to record Morse code transmissions on wax cylinders made by Edison Manufacturing Company.

[b] By October 1914, he had recorded other transmissions including the United States Navy station NAA sending time signals.

[25] During construction in August 1912, the US Navy began observing Sayville because it was reportedly controlled by a company that was under the influence of the government of the German Empire.

In August 1914, President Woodrow Wilson issued an executive order that prohibited radio communication of an "unneutral nature" from United States territory.

[31][32] The summer residence of German ambassador Johann Heinrich von Bernstorff in Cedarhurst, New York, on Long Island had a direct telegraph line to Sayville to relay diplomatic communication to Germany by wireless.

[11] The US Navy began to have doubts about the legitimate operation of the station after they learned that a technical advisor there, physicist and engineer Jonathan Zenneck, was a captain in the German marines.

[33] During the summer months, reception of wireless signals was difficult due to adverse atmospheric conditions that increased static.

In April 1915, the transmitter was upgraded from 35 to 100 kilowatts and three 492 foot (150 m) tall antenna towers were installed, transforming it into one of the most powerful transatlantic stations in this part of the world.

[31] By May the Telefunken station at Sayville and another at Tuckerton, New Jersey, were accused of sending messages to a German U-boat providing information that allowed the submarine to "ambush" and sink the RMS Lusitania.

[37] At the request of William J. Flynn, Chief of the Secret Service, Apgar commenced making regular recordings of the station on June 7, 1915.

The Sayville station was equipped with a type of Wheatstone system that used perforated paper tape to automatically key the transmitter.

"[37] Apgar transcribed the previous night's recording each morning by playing the wax cylinder on a phonograph at a much slower speed.

The headline of the story was subtitled: "Ambassador Breaks Pledges and with Captain Boy-Ed Has Tricked United States Authorities for Months.

"[43] Hiram Percy Maxim has noted that he and other amateurs also noticed these messages: "Apgar, the old sleuth, smelled something just about the time the rest of us did.

"[35] Flynn describes the importance of Apgar's contributions to the government seizure: "It was really his absolutely faithful records of all of the signals sent out from Sayville that caused the United States to seize the famous station.

"[35] Extensive coverage in the media in 1915 included a magazine cover story about Apgar that referred to him as "A Wireless Detective in Real Life.

"[29] A 1923 article by William J. Burns, then director of the Bureau of Investigation,[c] in Popular Radio included a photo of Apgar.

It was captioned "The Radio Detective Who Unfathomed the Famous 'Nauen Buzz'" and the description read: During the early days of the World War the incredibly rapid and undecipherable radio signals between the most powerful broadcasting station in Germany and the station of the "Telefunken Company" at Sayville, Long Island, N. Y., aroused the attention of the U. S. officials.

But it was radio amateur, Charles E. Apgar of Westfield, N. J., who finally found the solution by means of amplifiers that recorded these signals on wax phonograph cylinders.

The specific information recorded on the wax cylinders remained a closely guarded secret in the government archives for many years.

An example was displayed, along with the original receiving set that Apgar donated, as part of a museum exhibit in the lobby of Rockefeller Center.

[45] Apgar's work received renewed attention early during World War II when amateur radio operators began listening for "fifth column" activity such as odd coded messages sent from "mystery" stations.

A tape copy of the original aluminum phonograph discs and a transcript is in the Recorded Sound Collection of the Library of Congress.

[52] Broadcast historian Elizabeth McLeod considers Apgar's cylinders to be the earliest surviving recordings of a radio transmission based on research done by Dr. Michael Biel.

The title of the series was The Eagle's Eye: A True Story of the Imperial German Government's Spies and Intrigues in America.

An episode titled "The Great Hindu Conspiracy"[d] begins with a minor character named Charles E. Apgar.