Years ago when I worked at a local magic shop, the owner came down from his office and showed me an interesting little impromptu effect which used 3 cups and a ball (really this could be anything, as long as it fits under the cups). The effect goes as follows:

3 ordinary cups are presented and are put into a line in front of a volunteer. The positions of the cups (not the cups themselves) are number 1, 2 & 3. A ball (or other item) is handed to the volunteer and is told that when the performer turns his back, the volunteer is to place the ball underneath any one of the cups. With his back turned, the volunteer places the ball under one of the cups and is now instructed to switch the positions of the other two empty cups. Once this is done, the volunteer is asked to switch the positions of any cups he/she wants, but to call out which positions are being moved. For instance switching 1 & 3, 2 & 1, and so on until he or she is happy. Once finished, the performer turns around and instantly lifts the correct cup revealing the hidden ball. This can be done as many times as the volunteer likes and the performer is always 100% correct.

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Does anyone know the name of this effect or who created it? I don't know why, but this came to my mind the other day and I was trying to come up with the answer. I even went back to the magic shop and asked the owner and he barely even remembered the trick itself!

Any help would be great. Thanks in advance.

-rob

I think it is Bob... Hummer or Farmer. I overheard it being descibed at a magic shop. I was a rotten little kid. It was years later I heard the origin. I do know that Michael Skinner popularized it.

Al Koran’s “Note Under Cup” from Professional Presentations book was the first place for me. I am sure it is older.

The name Al Koran comes to mind for some reason. Does his 'Note under cup' predate the two Bobs? Al Koran's effect is identical up to the part when when the volunteer calls out positions as further movements take place. I generally perform Al Koran's version using china tea cups and money.

Lem you posted as I posted. Great minds think alike!

Good stuff guys! Thanks!

Lem, I knew that I had seen a version of this in print before and upon looking at my copy of Professional Presentations I found the routine (last effect in the book). However, I do believe you're right in that it might be older than that. If you look in the text you will find that Al Koran even states that there are "various mathematical variations" of the demonstration.

-rob

Martin Gardner describes a version of this in _Mathematics, Magic and Mystery_ (1956). He attributes it to Bob Hummer who marketed it in 1951 under the title "Mathematical Three-Card Monte."

Need more? I have the reference in front of me.

cheers,

Lin