One smoot is equal to Oliver Smoot's height at the time of the prank,. The bridge's length was measured to be plus or minus one ear, with the "plus or minus" intended to express uncertainty of measurement. Over the years the "or minus" portion has gone astray in many citations, including the markings at the site itself, but is recorded on a plaque by Smoot's college class.
History
Oliver Smoot was selected because he was the pledge deemed shortest and "most scientifically named." To implement his use as a unit of measure, Smoot repeatedly lay down on the bridge, let his companions mark his new position in chalk or paint, and then got up again. Eventually, he got tired from all this exercise and was carried thereafter by the fraternity brothers to each new position. Oliver Smoot graduated from MIT with the class of 1962, became a lawyer, and later became chairman of the American National Standards Institute and then, president of the International Organization for Standardization. He is the cousin of Nobel Prize winner George Smoot. Public knowledge and interest in the story began when Holiday investigated the marks on the bridge years later, and published an interview with Smoot. The prank's fiftieth anniversary was commemorated on October 4, 2008 as Smoot Celebration Day at MIT, which Smoot attended. In 2011, "smoot" was one of the 10,000 new words added to the fifth edition of the American Heritage Dictionary. A 2016 April Fools' Day article by the MIT Alumni Association announced that MIT would recalibrate the smoot to 65.7500 inches and the ear to 2.48031 inches, and bridge would thus be 372 smoots give or take 11 ears. On May 7 of that year, Oliver Smoot served as Grand Marshal of the alumni parade across the bridge, celebrating the 100th anniversary of MIT's move from Boston to Cambridge.
Practical use
The bridge is marked with painted markings indicating how many smoots there are from where the sidewalk begins on the Boston river bank, and with a number every ten smoots. The marks are repainted each semester by the incoming associate member class of Lambda Chi Alpha. Markings typically appear every 10 smoots, but additional marks appear at other numbers in between. For example, the 70-smoot mark is accompanied by a mark for 69. The 182.2-smoot mark is accompanied by the words "Halfway to Hell" and an arrow pointing towards MIT. Each class also paints a special mark for their graduating year. The markings are recognized as s on the bridge, to the degree that during the bridge renovations that occurred in the 1980s, the Cambridge police department requested that the markings be restored, as they were used routinely in police reports to identify locations on the bridge. The renovators at the Massachusetts Highway Department went one better, scoring the concrete surface of the sidewalk on the bridge at intervals instead of the conventional. The Lambda Zeta chapter of Lambda Chi Alpha, which created the smoot markings, continues to repaint the markings once or twice per year. Google Calculator also incorporates smoots, which it reckons at exactly 67 inches. Google also used the smoot as an optional unit of measurement in their Google Earth software and Google Mapsdistance measurement tool. In 2014, Google introduced a new Maps interface with a measurement tool that gives distances only in feet/miles and meters/kilometers. MIT's student-run college radio station, WMBR, broadcasts at a wavelength of 2 smoots.
