**Martin Gardner** Rotation, 1993**Martin Gardner** Reflection: top/bottom, 1996**Martin Gardner / Doctor Matrix** Rotation, 1996**Martin Gardner / Mathematical Games** Oscillation, 1996

Created for the Gathering for Gardner, January 1996, Atlanta Georgia.

Martin Gardner books and magazine articles about mathematics and science have charmed several generations of readers into careers with a mathematical twist. His Scientific American column Mathematical Games, which ran for 25 years, inspired my own career as a puzzle designer.

In January 1996 the second Gathering for Gardner took place in Atlanta Georgia. Over a hundred magicians, mathematicians, skeptics of psychic phenomena (Gardner is a major player in the Committee for the Scientific Investigation of Claims of the Paranormal) and other mischief makers entertained each other for several days with lectures, performances, and heated shmoozing. One of the events was a round robin exchange of small gifts made of paper; mine included a series of four inversions on "Martin Gardner".

The first inversion reads the same upside down. Shown below is an earlier version of the design, which appeared in my book*Inversions* in 1981. Notice that the central letter of the design is G. In the new improved version, I used an R with one vertical stroke instead of two, which shifts the visual rhythm of the lettering over by one stroke, so that G is no longer the central letter. Not only are the three R's now consistent, MARTIN can now turn cleanly into GARDNER.

evisiting the name was interesting challenge. Hold a mirror horizontally just below the second inversion and you will be able to read both MARTIN and GARDNER at the same time. The third inversion turns Gardner into his adventurous alter ego Doctor Matrix, who would sometimes invade Mathematical Games with tales of mathematical intrigue. Finally, the fourth inversion takes advantage of the fact that both Martin Gardner and Mathematical Games have the same initials to create what are known as perceptual shift ambigrams; the shift between one reading and the other takes place in your mind.