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IBM 210 - SAM 88

Inventor’s Notebook Issue #4 – DuoSphere

The Inventor's Notebook
Issue #4 - DuoSphere
Karl Rabe

Several months ago I framed up an idea I had to develop a two-man Stratosphere. In this issue I'll share how I turned the idea into reality and how "A funny thing happened on the way to the Forum".


If you aren't familiar with Stratosphere, it is probably because you just don't know it by that name. It typically involves a clear tube, three balls and a solid tube.

Ad copy reads...

Although there is only enough room in the tube for the three balls, one on top of the other, the ball placed on top of the three magically appears on the bottom or in the center of the stack of three. The red one seems to be the ball that likes to do the wandering.... etc

My idea was to create a two man presentation by having two sets of tubes and balls and having the balls appear to move back and forth between the two tubes rather than change sequence within the tube.

I started with this story board. Click on the image to launch it in a bigger window.

The first thing was to plan the moves. I consider this choreographing the routine. I know how the gimmick works and what it can and can't do. The question is, how do I arrange the moves in a logical sequence that tells a story within the constraints of the gimmick. This conceptually was very similar to planning a linking rings or multiplying bottles routine.

For this I turned to a tool I have used before... an Excel Spreadsheet. The cells of the spreadsheet are laid out to mimic the tubes in sequence. Cells above the tubes show the sequence of balls entering the tube. Formulas automatically display what will be in the tube for the given input sequence knowing the loaded ball from the prior step. This allows me to play with different sequences quickly and see how it works out. You can click on the image to see a bigger copy and if you are really interested in more about the spreadsheet I'll publish more in depth in the future.

You will see in the end, the final routine is different from the story board. The concept is the same but there are differences. After building the apparatus and doing a few trial runs, I was back to the spreadsheet to make adjustments. One key point I realized and adjusted for was that it was important to have the odd color ball appear in the middle of the stack. This is much harder for the spectator to reverse engineer the sequence and I think seems more magical and impossible.

Next was the apparatus. Buy or build? Oh how I wish I had bought. That is two weeks of my life I will never get back that was spent in search of the right size tubes, the right balls, material for a gimmick, etc. Why build? First the apparatus is not inexpensive $60-$80 each and I needed two. Second, I had read in my research that the gimmick could be noisy and I didn't think I could train Bill with the finesse needed to eliminate that issue. Third the graphics on the tubes would not meet my needs as they needed to be color neutral as I was using a different color scheme and sequence. Finally, although I complain I enjoy the process.

One of the Custom DuoSphere Tubes

I am happy to share the gimmick I devised for this privately or at the club if you ask. As far as I know, it is novel. It is completely silent. It is foolproof in that you cannot push the last ball too far by mistake. It self-centers the ball going down the tube. The inside of the tube cannot be shown however.

I also lined the top section of the solid tubes with black adhesive felt so there wouldn't be any reflections to give away the secret. The solid tube is long enough that there are no angle issues. Seated spectators at just 2 ft away cannot see anything they shouldn't.

I prefer a thick base so that the two tubes side-by-side on the table don't have a significant height difference.

The "Instructions" that are displayed during the routine play a very important part. First they set up the comedy for changing the rules. They also make sure the audience is 100% clear on what should happen without needing to think too much. This reminds me a bit of Levent's Sympathetic Silks routine with the Knot / not signs and the traveling K, one purpose of which is to make sure the audience is clear on what is what.

In closing, although I am pleased with the routine I am still working on  a better ending. It is a little flat I think and needs something to give it zing at the end.

Here is a video of the first public performance.


"A funny thing happened on the way to the Forum", or should I say a funny thing happened in developing DuoSphere. As I was wrapping up the DuoSphere build and looking over the abandon remnants of toilet brush tubes and plastic balls and other bits and pieces when inspiration hit. Within about an hour I assembled these bits and pieces and a few other remnants into a completely different take on Stratosphere. Nothing like DuoSphere, but a completely novel branding and routine theme for Stratosphere which actually makes sense (in a twisted magic way). I am inclined to say it is better and more commercial than DuoSphere. Stay tuned for next month's Inventor's Notebook to learn more.

“There is no such thing as a new idea. It is impossible. We simply take a lot of old ideas and put them into a sort of mental kaleidoscope. We give them a turn and they make new and curious combinations. We keep on turning and making new combinations indefinitely; but they are the same old pieces of colored glass that have been in use through all the ages.” - Mark Twain


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