– The idea-a-minute Jonas Salk didn’t always have time to capture his thoughts on the yellow legal pads he always kept within reach.

So he spent hour after hour talking into an audio recorder when he was developing the world’s first effective polio vaccine and creating the now famous research institute in La Jolla, Calif., that bears his name.

Most of those recordings haven’t been heard in at least 50 years. But UC San Diego has asked a specialty company to digitize more than 170 hours of recordings that were made on an audograph, a clunky device that became obsolete long ago. The recordings are part of the nearly 1,000 boxes of papers, media and photographs that the university maintains on Salk.

“It is one of the most significant collections we hold and now we can use a newer technology to make the content available for the first time in at least 50 years,” said Lynda Claassen, director of the Mandeville Special Collections at UC San Diego’s Geisel Library. “The hope is that it will be used by scholars to create new history, and maybe new science.”

Salk began dictating the recordings in 1949, three years after the Gray Manufacturing Company introduced a sound system called the audograph.

The discs are “as light as a sheet of tinfoil,” Stefan Elnabli, a librarian at UC San Diego.

Salk had trouble sleeping, largely because his mind was so filled with science problems. He’d frequently wake up and write his thoughts on legal pads. About daylight, he would often used the audograph.

“There could be some gems on those recordings. My father used the machine to dictate his thoughts about things like journal articles and polio and things he was learning,” said Peter Salk, one of Salk’s sons, about the recordings from 1949 to 1967. “It will be a very intimate thing to hear.”