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Topic: Boomerang (Jastrow) illusion
Message: Posted by: pprevos (Feb 27, 2016 07:38PM)
Hi,

I am writing a booklet on magic tricks based on geometry and am doing some research on the baffling boomerangs, or the Jastrow Illusion.

See: http://mathworld.wolfram.com/JastrowIllusion.html

This visual illusion is by the way still subject to perception reearch: http://ipe.sagepub.com/content/6/6/2041669515622090.full

I remember once seeing a close-up version that uses three boomerangs. Can somebody please tell me where I can read about this, view the performance or purchase the items?

Peter
Message: Posted by: Dick Oslund (Mar 16, 2016 06:00AM)
Hi "down under" from "up above" (I'm in the Upper Peninsula of Michigan. I'm so far north, I can drive 350 miles south, and enter Canada._

I've been using a brief routine about sensory illusions, demonstrating how our five senses "fool" our minds, in school assembly programs for about 40 years. It's an educational feature that helps book the program!

The sequence begins with the Jastrow Area (boomerangs). I follow it with the "six spot, three spot, four spot, one spot, eight spot, card, and usually close it with a "test" to "see" if they've understood. The "test" is the visible penetration of a silk through the microphone stand.The entire routine runs about five minutes.

This routine is done in the "second spot" (five minutes after the opening of the program. The students, especially high school kids, now appreciate that I'm going to fool them, but, not make fools of them! --And, the teachers appreciate the educational aspect.

In high schools (I perform for all levels Kindergarten thru high schools--in rural areas, I often have all grades in one audience!)I follow up later with a tactile ilusion. I use the old bit as shown in Ottakar Fischer's "Illustrated Magic" of the crossed fingers, touching a ball. I involve the entire audience by having them touch their noses with the crossed fingers. The students really "react" to the sensation!

I wrote up the entire routine in my book ("DICK OSLUND--ROAD SCHOLAR") You can PM John Kanawati (from Australia)for a review of the book!

I've never seen a routine with three boomerangs! It sounds intriguing!

Dick
Message: Posted by: federico luduena (Mar 16, 2016 11:47AM)
Thanks for sharing your findings.

This one adds a third boomerang to great effect:

https://www.mymagic.com/p/puzzles/tenyo-sakkaku-scale-puzzle

Another routine worth studying is "Top of the Bill", by Terri Rogers, which opens her book [i]Top Secrets[/i].
Message: Posted by: pprevos (Mar 16, 2016 08:18PM)
Thanks Federico, that is what I was looking for. I have a copy of the Rogers routine - I like it a lot. I am collecting applications of the Jastrow illusion in magic.

What I hvave learnt through my research is the best way to present the Jastrow Illusion is to add a layer of deception beyond the curiosity of the two swapping sizes. The third boomerang achieves this very well. Terri's idea to give the spectator a pair is another example. The Ia Adair versions add a nice bit of theatre by turning the boomerangs into a butterfly or monkey.

Dick, love your work on this. You had an impressive career; I'll put your book on my wish list.

Regards

Peter