MIT Creates "Klein" Unit, Measures Bridge in 442 Kleins

Nearly 70 years after MIT students famously measured a Boston bridge in "smoots," a new generation has created another quirky unit of measurement to honor an underwater exploration pioneer.

On April 4, an MIT team measured the Longfellow Bridge connecting Boston and Cambridge in "kleins," a new unit named after Martin Klein '62. One klein equals 4 feet and 9.5 inches, precisely the height of the man who revolutionized how we explore the ocean floor.

Klein is known worldwide as the father of commercial side-scan sonar. His technology has helped locate some of history's most famous shipwrecks, including the Titanic, the RMS Lusitania, and the treasure-filled Nuestra Señora de Atocha.

The measuring expedition was led by Makenna Reilly, a second-year mechanical engineering student, and Andrew Bennett, an MIT Sea Grant education administrator. More than a dozen surveyors joined them, including students, alumni, faculty, and staff from MIT and other institutions.

In a fitting tribute to Klein's sonar work, the team used a "side-scan" method for their survey. Klein himself reclined on a custom-built wooden cart topped with a special pillow, acting as the official observation device by looking to the sides as the team pulled him along the bridge.

The expedition revealed some charming discoveries along the way. The team spotted a Duck Boat passing underneath, a mermaid tail, a kayak paddle, and even a sleeping goose.

The Ripple Effect

This playful tradition carries forward MIT's legacy of creative pranks that blend engineering, humor, and heart. The original 1958 smoot measurement has endured for nearly seven decades, with the markers still painted on the Massachusetts Avenue Bridge today.

The Longfellow Bridge now has its own piece of history. It measures exactly 442 kleins (plus 2 legs) and was playfully renamed the "Shortfellow Bridge" in a ceremony following the event.

Klein serves on the MIT Sea Grant Advisory Board and the MIT Museum Collections Committee. He's a life fellow of both the Marine Technology Society and the Explorers Club, an international organization dedicated to field exploration and scientific inquiry.

The celebration honored both Klein's 85th birthday and his classmate Oliver Smoot, whose 1958 adventure started it all. Their stories remind us that the best tributes mix respect with joy, and that measuring progress sometimes means having fun along the way.