I don't know much about Gladys Hardeen. Her passport application says she was born February 15, 1902 and Genii reported her death in Daytona, Florida on February 17, 1966. But according to Jon Oliver, Dash and Elsie Fozzard married in 1904 (this info came direct from Hardeen's son, Harry Houdini Hardeen). Was Gladys a stepchild? She later assisted Douglas Geoffrey aka Hardeen Jr.
Houdini developed Radio of 1950 for his full evening show of 1925-26. A review of Houdini's first performance of his full evening show in Baltimore called the effect "Radio 1925." Hard to know if this was a mistake or if Houdini later changed the name. In her 2003 booklet, Touring With Houdini, assistant Dorothy Young described how the illusion was staged:
Radio was quite new in 1925. The first commercial station KDKA, had gone on the air in Pittsburg, Pennsylvania just five years earlier. So a magic trick about radio was a very up-to-the-minute feature.
To present the illusion of Radio of 1950, Houdini walked around and behind an empty table in the center of the stage so the audience could see there were no mirrors underneath. Then two assistants put the "radio" on top, completely filling the table.
"I would like to present my original conception of what radio will be like in 25 years." Houdini said, "Tune in to any station and get the girl you want. No, gentlemen, it is not for sale."
He opened the entire front, which consisted of two doors, and removed a panel that held various coils and transformers and large glass tubes the size of light bulbs that were used before transistors were invented. The audience could see there was nothing else inside. He replaced the panel and closed the front.
"Now," he said, "we will tune in Pittsburg Station KDKA." He began twisting the dials. Suddenly a voice from the radio speaker announced, "Miss Dorothy Young, doing The Charleston." That was my cue. As the orchestra started playing that popular jazz dance, I threw open the lid, popped up my head at one end and kicked one leg up in the air. I kicked the other leg, clicked my feet together, jumped up, and curtsied. Houdini opened the front of the radio, lived me down, and I went into a wild Charleston as the audience laughed and applauded.
Hardeen inherited the effect after Houdini's death and featured it in his own show. After he died, it was put up for sale for $125 along with other Hardeen-Houdini apparatus. Today the whereabouts of the Radio of 1950 illusion is unknown.
Below is a shot of Houdini himself doing Radio of 1950, showing the appearance of "Radio Girl" Dorothy Young. And if you're dying to know how this trick was done, check out Patrick Culliton's Houdini The Key (page 402). He gives a very good explanation of the method.
Thanks to Mark Willoughby for sharing this special photo and for the intel on Gladys Hardeen.