James H. Williams, Jr. and the world's largest yo-yo, 1974

World's largest yo-yo, 1974
Courtesy MIT Museum

Mechanical engineering professor James H. Williams, Jr. with students and "the world's largest yo-yo" in front of MIT's Cecil and Ida Green Building, January 1974.

James Henry Williams, Jr. '67, SM '68, professor of mechanical engineering, led a group of 10 students in building "the world's largest yo-yo" during MIT's Independent Activities Period (IAP) in 1974 and tested it from the Cecil and Ida Green Building (54), the tallest on campus. 


From "Prof. Williams Spins His Wheels and Comes Up with a Colossal, Working Yo-yo," People (26 January 1974)

When the 35-pound contraption, made of two bicycle wheels, was ready, Williams took it to the roof of a 21-story building at MIT. He anchored the cord to an I beam, hooked up a motor which jerked the line rhythmically like a finger and let the yo-yo drop. The wheels, revolving up to 1,000 times a minute, reached a speed of more than 80 miles an hour. Then, the yo-yo climbed more than two-thirds of the way back up the 400-pound-test-weight nylon cord.

The scientific principle involved, according to Williams, is the conversion of the potential energy of a poised yoyo into kinetic energy and vice-versa. “I am interested in the dynamics of toys,” says Williams, “because they have lots of subtle and sophisticated aspects in a kinetic sense. Besides, too many technical people cultivate their gardens too tightly.”

After high school, Williams himself worked as a machinist in a shipbuilding yard in his native Newport News, Va. Then he went back to school and has earned two MIT degrees, a Cambridge doctorate and an award for outstanding undergraduate teaching. He lives with his wife, Karen, a poet, and his 5-year-old son, “J.T.,” in an MIT dorm where he is the house master. He is an intramural football and basketball player and a flutist.

Williams’ inspired students now want to build a giant Frisbee and sail it across the Charles River with, yoicks, the professor aboard. “It’s too dangerous,” he says...


Williams was offered $5,000 for the yo-yo by a Las Vegas casino (“I feel sensitive about selling it”), and laughed off suggestions that he drop it from Canada’s tallest structure, Toronto’s 1,800-foot Canadian National Tower. “There were all sorts of radio and TV offers,” he says wearily.

Timeline: 1970s
School: School of Engineering
Department: Mechanical Engineering
Career: EducationEngineering
Object: Image
Collection: Critical Mass 1955-1968, Integration and Differentiation 1969-1994, Students