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New England News

Hampshire College Changes Speed Limit Sign In Nod To Math Professor

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Hampshire College
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David Kelly next to one of the 17 mph speed limit signs at Hampshire College in Amherst, Mass.

Students, faculty and staff at Hampshire College in Amherst are able to move around campus a bit faster thanks to a recent speed limit change. But, it wasn’t done to help students get to class on time.

The speed limit signs at Hampshire College might draw some double takes. That’s because some of them read 17 miles per hour – not sticking with the standard of going by fives. It’s the college’s way of honoring retired math professor David Kelly, who’s long been fascinated by the number 17.

“Well I sort of had been hoping for it for 40 years, but it certainly was a pleasant shock,” said Kelly.

As Kelly points out, 17 has many mathematical characteristics beyond being a prime number. He says throughout history, mathematicians have used 17 to test theorems.

“A regular 17-sided polygon can be constructed with straightedge and compass, classical Euclidean tools,” Kelly explained. “For 2,000 years people knew that you could use a ruler and a compass to construct an equilateral triangle, a square or a pentagon. That was where it stood for 2,000 years until [Carl Friedrich] Gaus – his first mathematical result showed that a regular 17-gon can also be constructed.”

In addition, 17 is the least number of clues that a Sudoku puzzle can have in order to produce a unique solution and there are 17 columns on the long side of the Parthenon in Greece. Kelly even has a 17 quip relating to public radio and the late NPR senior news analyst Daniel Schorr.

“He discovered while reading a list on-air, it had been given to him just before he went on-air, he discovered that he was number 17 on [President] Nixon’s list of enemies,” said Kelly.

Kelly mentioned the speed limit change when the college asked him how he wanted to celebrate his retirement in 2014. Faculty including President Jonathan Lash got on board and made it happen. Director of Facilities and Grounds Larry Archey says the college made the signs for the road that used to be 15 miles per hour.

“Where all the real feedback came was when we put them into the ground,” Archey said. “I was getting emails and phone calls for days of ‘What’s that all about?’ It was pretty exciting because it got the word out really quickly.”

Kelly still teaches a summer studies program for high schoolers, including some 17-year-olds, at Hampshire, which he started in 1971. Of course he does a special lecture on July 17th, which is also Yellow Pigs Day. The day is dedicated to Kelly and another Princeton student who in the 1960s went about analyzing the properties of 17 and created a mythical yellow pig with 17 toes, teeth and eyelashes — you get the idea. Kelly says students have latched onto the uniqueness of 17 over the years.

“They understand my passion for 17 and then they start noticing 17s in the news,” Kelly said. “When the number of Republican candidates hit 17, I got congratulatory emails about it.”

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