Having a prediction envelope hanging from the ceiling on stage, and later switching it with the aid of a Chair Servante — the chair is used to climb up and take down the envelope — was published by Theo Bamberg (Okito) as “Bamberg's Envelope Mystery” in The Sphinx, Vol. 16 No. 2, Apr. 1917, p. 33.
In later modifications, the prediction is added behind the envelope instead of switching the whole envelope, thus the envelope never has to be out of view. The earliest use of that addition found so far is Dr. William Weyeneth's “L'enveloppe spirite” in La Baguette Magique, No. 22, Aug. 1948, p. 5.